diff --git a/les/benchmark.go b/les/benchmark.go
index 42eeef10f3..dbb10a5c2a 100644
--- a/les/benchmark.go
+++ b/les/benchmark.go
@@ -42,7 +42,7 @@ type requestBenchmark interface {
 	// init initializes the generator for generating the given number of randomized requests
 	init(h *serverHandler, count int) error
 	// request initiates sending a single request to the given peer
-	request(peer *peer, index int) error
+	request(peer *serverPeer, index int) error
 }
 
 // benchmarkBlockHeaders implements requestBenchmark
@@ -72,11 +72,11 @@ func (b *benchmarkBlockHeaders) init(h *serverHandler, count int) error {
 	return nil
 }
 
-func (b *benchmarkBlockHeaders) request(peer *peer, index int) error {
+func (b *benchmarkBlockHeaders) request(peer *serverPeer, index int) error {
 	if b.byHash {
-		return peer.RequestHeadersByHash(0, 0, b.hashes[index], b.amount, b.skip, b.reverse)
+		return peer.requestHeadersByHash(0, b.hashes[index], b.amount, b.skip, b.reverse)
 	} else {
-		return peer.RequestHeadersByNumber(0, 0, uint64(b.offset+rand.Int63n(b.randMax)), b.amount, b.skip, b.reverse)
+		return peer.requestHeadersByNumber(0, uint64(b.offset+rand.Int63n(b.randMax)), b.amount, b.skip, b.reverse)
 	}
 }
 
@@ -95,11 +95,11 @@ func (b *benchmarkBodiesOrReceipts) init(h *serverHandler, count int) error {
 	return nil
 }
 
-func (b *benchmarkBodiesOrReceipts) request(peer *peer, index int) error {
+func (b *benchmarkBodiesOrReceipts) request(peer *serverPeer, index int) error {
 	if b.receipts {
-		return peer.RequestReceipts(0, 0, []common.Hash{b.hashes[index]})
+		return peer.requestReceipts(0, []common.Hash{b.hashes[index]})
 	} else {
-		return peer.RequestBodies(0, 0, []common.Hash{b.hashes[index]})
+		return peer.requestBodies(0, []common.Hash{b.hashes[index]})
 	}
 }
 
@@ -114,13 +114,13 @@ func (b *benchmarkProofsOrCode) init(h *serverHandler, count int) error {
 	return nil
 }
 
-func (b *benchmarkProofsOrCode) request(peer *peer, index int) error {
+func (b *benchmarkProofsOrCode) request(peer *serverPeer, index int) error {
 	key := make([]byte, 32)
 	rand.Read(key)
 	if b.code {
-		return peer.RequestCode(0, 0, []CodeReq{{BHash: b.headHash, AccKey: key}})
+		return peer.requestCode(0, []CodeReq{{BHash: b.headHash, AccKey: key}})
 	} else {
-		return peer.RequestProofs(0, 0, []ProofReq{{BHash: b.headHash, Key: key}})
+		return peer.requestProofs(0, []ProofReq{{BHash: b.headHash, Key: key}})
 	}
 }
 
@@ -144,7 +144,7 @@ func (b *benchmarkHelperTrie) init(h *serverHandler, count int) error {
 	return nil
 }
 
-func (b *benchmarkHelperTrie) request(peer *peer, index int) error {
+func (b *benchmarkHelperTrie) request(peer *serverPeer, index int) error {
 	reqs := make([]HelperTrieReq, b.reqCount)
 
 	if b.bloom {
@@ -163,7 +163,7 @@ func (b *benchmarkHelperTrie) request(peer *peer, index int) error {
 		}
 	}
 
-	return peer.RequestHelperTrieProofs(0, 0, reqs)
+	return peer.requestHelperTrieProofs(0, reqs)
 }
 
 // benchmarkTxSend implements requestBenchmark
@@ -189,9 +189,9 @@ func (b *benchmarkTxSend) init(h *serverHandler, count int) error {
 	return nil
 }
 
-func (b *benchmarkTxSend) request(peer *peer, index int) error {
+func (b *benchmarkTxSend) request(peer *serverPeer, index int) error {
 	enc, _ := rlp.EncodeToBytes(types.Transactions{b.txs[index]})
-	return peer.SendTxs(0, 0, enc)
+	return peer.sendTxs(0, enc)
 }
 
 // benchmarkTxStatus implements requestBenchmark
@@ -201,10 +201,10 @@ func (b *benchmarkTxStatus) init(h *serverHandler, count int) error {
 	return nil
 }
 
-func (b *benchmarkTxStatus) request(peer *peer, index int) error {
+func (b *benchmarkTxStatus) request(peer *serverPeer, index int) error {
 	var hash common.Hash
 	rand.Read(hash[:])
-	return peer.RequestTxStatus(0, 0, []common.Hash{hash})
+	return peer.requestTxStatus(0, []common.Hash{hash})
 }
 
 // benchmarkSetup stores measurement data for a single benchmark type
@@ -283,18 +283,17 @@ func (h *serverHandler) measure(setup *benchmarkSetup, count int) error {
 	var id enode.ID
 	rand.Read(id[:])
 
-	clientPeer := newPeer(lpv2, NetworkId, false, p2p.NewPeer(id, "client", nil), clientMeteredPipe)
-	serverPeer := newPeer(lpv2, NetworkId, false, p2p.NewPeer(id, "server", nil), serverMeteredPipe)
-	serverPeer.sendQueue = newExecQueue(count)
-	serverPeer.announceType = announceTypeNone
-	serverPeer.fcCosts = make(requestCostTable)
+	peer1 := newServerPeer(lpv2, NetworkId, false, p2p.NewPeer(id, "client", nil), clientMeteredPipe)
+	peer2 := newClientPeer(lpv2, NetworkId, p2p.NewPeer(id, "server", nil), serverMeteredPipe)
+	peer2.announceType = announceTypeNone
+	peer2.fcCosts = make(requestCostTable)
 	c := &requestCosts{}
 	for code := range requests {
-		serverPeer.fcCosts[code] = c
+		peer2.fcCosts[code] = c
 	}
-	serverPeer.fcParams = flowcontrol.ServerParams{BufLimit: 1, MinRecharge: 1}
-	serverPeer.fcClient = flowcontrol.NewClientNode(h.server.fcManager, serverPeer.fcParams)
-	defer serverPeer.fcClient.Disconnect()
+	peer2.fcParams = flowcontrol.ServerParams{BufLimit: 1, MinRecharge: 1}
+	peer2.fcClient = flowcontrol.NewClientNode(h.server.fcManager, peer2.fcParams)
+	defer peer2.fcClient.Disconnect()
 
 	if err := setup.req.init(h, count); err != nil {
 		return err
@@ -305,7 +304,7 @@ func (h *serverHandler) measure(setup *benchmarkSetup, count int) error {
 
 	go func() {
 		for i := 0; i < count; i++ {
-			if err := setup.req.request(clientPeer, i); err != nil {
+			if err := setup.req.request(peer1, i); err != nil {
 				errCh <- err
 				return
 			}
@@ -313,7 +312,7 @@ func (h *serverHandler) measure(setup *benchmarkSetup, count int) error {
 	}()
 	go func() {
 		for i := 0; i < count; i++ {
-			if err := h.handleMsg(serverPeer, &sync.WaitGroup{}); err != nil {
+			if err := h.handleMsg(peer2, &sync.WaitGroup{}); err != nil {
 				errCh <- err
 				return
 			}
diff --git a/les/client.go b/les/client.go
index 36d5a8d2fe..dfd0909778 100644
--- a/les/client.go
+++ b/les/client.go
@@ -49,6 +49,7 @@ import (
 type LightEthereum struct {
 	lesCommons
 
+	peers      *serverPeerSet
 	reqDist    *requestDistributor
 	retriever  *retrieveManager
 	odr        *LesOdr
@@ -80,7 +81,7 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 	}
 	log.Info("Initialised chain configuration", "config", chainConfig)
 
-	peers := newPeerSet()
+	peers := newServerPeerSet()
 	leth := &LightEthereum{
 		lesCommons: lesCommons{
 			genesis:     genesisHash,
@@ -88,9 +89,9 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 			chainConfig: chainConfig,
 			iConfig:     light.DefaultClientIndexerConfig,
 			chainDb:     chainDb,
-			peers:       peers,
 			closeCh:     make(chan struct{}),
 		},
+		peers:          peers,
 		eventMux:       ctx.EventMux,
 		reqDist:        newRequestDistributor(peers, &mclock.System{}),
 		accountManager: ctx.AccountManager,
@@ -225,7 +226,7 @@ func (s *LightEthereum) EventMux() *event.TypeMux           { return s.eventMux
 // network protocols to start.
 func (s *LightEthereum) Protocols() []p2p.Protocol {
 	return s.makeProtocols(ClientProtocolVersions, s.handler.runPeer, func(id enode.ID) interface{} {
-		if p := s.peers.Peer(peerIdToString(id)); p != nil {
+		if p := s.peers.peer(peerIdToString(id)); p != nil {
 			return p.Info()
 		}
 		return nil
@@ -253,7 +254,7 @@ func (s *LightEthereum) Start(srvr *p2p.Server) error {
 // Ethereum protocol.
 func (s *LightEthereum) Stop() error {
 	close(s.closeCh)
-	s.peers.Close()
+	s.peers.close()
 	s.reqDist.close()
 	s.odr.Stop()
 	s.relay.Stop()
diff --git a/les/client_handler.go b/les/client_handler.go
index 7fdb165719..d04574c8c7 100644
--- a/les/client_handler.go
+++ b/les/client_handler.go
@@ -65,7 +65,7 @@ func newClientHandler(ulcServers []string, ulcFraction int, checkpoint *params.T
 	}
 	handler.fetcher = newLightFetcher(handler)
 	handler.downloader = downloader.New(height, backend.chainDb, nil, backend.eventMux, nil, backend.blockchain, handler.removePeer)
-	handler.backend.peers.notify((*downloaderPeerNotify)(handler))
+	handler.backend.peers.subscribe((*downloaderPeerNotify)(handler))
 	return handler
 }
 
@@ -82,7 +82,8 @@ func (h *clientHandler) runPeer(version uint, p *p2p.Peer, rw p2p.MsgReadWriter)
 	if h.ulc != nil {
 		trusted = h.ulc.trusted(p.ID())
 	}
-	peer := newPeer(int(version), h.backend.config.NetworkId, trusted, p, newMeteredMsgWriter(rw, int(version)))
+	peer := newServerPeer(int(version), h.backend.config.NetworkId, trusted, p, newMeteredMsgWriter(rw, int(version)))
+	defer peer.close()
 	peer.poolEntry = h.backend.serverPool.connect(peer, peer.Node())
 	if peer.poolEntry == nil {
 		return p2p.DiscRequested
@@ -94,8 +95,8 @@ func (h *clientHandler) runPeer(version uint, p *p2p.Peer, rw p2p.MsgReadWriter)
 	return err
 }
 
-func (h *clientHandler) handle(p *peer) error {
-	if h.backend.peers.Len() >= h.backend.config.LightPeers && !p.Peer.Info().Network.Trusted {
+func (h *clientHandler) handle(p *serverPeer) error {
+	if h.backend.peers.len() >= h.backend.config.LightPeers && !p.Peer.Info().Network.Trusted {
 		return p2p.DiscTooManyPeers
 	}
 	p.Log().Debug("Light Ethereum peer connected", "name", p.Name())
@@ -112,20 +113,20 @@ func (h *clientHandler) handle(p *peer) error {
 		return err
 	}
 	// Register the peer locally
-	if err := h.backend.peers.Register(p); err != nil {
+	if err := h.backend.peers.register(p); err != nil {
 		p.Log().Error("Light Ethereum peer registration failed", "err", err)
 		return err
 	}
-	serverConnectionGauge.Update(int64(h.backend.peers.Len()))
+	serverConnectionGauge.Update(int64(h.backend.peers.len()))
 
 	connectedAt := mclock.Now()
 	defer func() {
-		h.backend.peers.Unregister(p.id)
+		h.backend.peers.unregister(p.id)
 		connectionTimer.Update(time.Duration(mclock.Now() - connectedAt))
-		serverConnectionGauge.Update(int64(h.backend.peers.Len()))
+		serverConnectionGauge.Update(int64(h.backend.peers.len()))
 	}()
 
-	h.fetcher.announce(p, p.headInfo)
+	h.fetcher.announce(p, &announceData{Hash: p.headInfo.Hash, Number: p.headInfo.Number, Td: p.headInfo.Td})
 
 	// pool entry can be nil during the unit test.
 	if p.poolEntry != nil {
@@ -143,7 +144,7 @@ func (h *clientHandler) handle(p *peer) error {
 
 // handleMsg is invoked whenever an inbound message is received from a remote
 // peer. The remote connection is torn down upon returning any error.
-func (h *clientHandler) handleMsg(p *peer) error {
+func (h *clientHandler) handleMsg(p *serverPeer) error {
 	// Read the next message from the remote peer, and ensure it's fully consumed
 	msg, err := p.rw.ReadMsg()
 	if err != nil {
@@ -297,7 +298,7 @@ func (h *clientHandler) handleMsg(p *peer) error {
 			Obj:     resp.Status,
 		}
 	case StopMsg:
-		p.freezeServer(true)
+		p.freeze()
 		h.backend.retriever.frozen(p)
 		p.Log().Debug("Service stopped")
 	case ResumeMsg:
@@ -306,7 +307,7 @@ func (h *clientHandler) handleMsg(p *peer) error {
 			return errResp(ErrDecode, "msg %v: %v", msg, err)
 		}
 		p.fcServer.ResumeFreeze(bv)
-		p.freezeServer(false)
+		p.unfreeze()
 		p.Log().Debug("Service resumed")
 	default:
 		p.Log().Trace("Received invalid message", "code", msg.Code)
@@ -315,8 +316,8 @@ func (h *clientHandler) handleMsg(p *peer) error {
 	// Deliver the received response to retriever.
 	if deliverMsg != nil {
 		if err := h.backend.retriever.deliver(p, deliverMsg); err != nil {
-			p.responseErrors++
-			if p.responseErrors > maxResponseErrors {
+			p.errCount++
+			if p.errCount > maxResponseErrors {
 				return err
 			}
 		}
@@ -325,12 +326,12 @@ func (h *clientHandler) handleMsg(p *peer) error {
 }
 
 func (h *clientHandler) removePeer(id string) {
-	h.backend.peers.Unregister(id)
+	h.backend.peers.unregister(id)
 }
 
 type peerConnection struct {
 	handler *clientHandler
-	peer    *peer
+	peer    *serverPeer
 }
 
 func (pc *peerConnection) Head() (common.Hash, *big.Int) {
@@ -340,18 +341,18 @@ func (pc *peerConnection) Head() (common.Hash, *big.Int) {
 func (pc *peerConnection) RequestHeadersByHash(origin common.Hash, amount int, skip int, reverse bool) error {
 	rq := &distReq{
 		getCost: func(dp distPeer) uint64 {
-			peer := dp.(*peer)
-			return peer.GetRequestCost(GetBlockHeadersMsg, amount)
+			peer := dp.(*serverPeer)
+			return peer.getRequestCost(GetBlockHeadersMsg, amount)
 		},
 		canSend: func(dp distPeer) bool {
-			return dp.(*peer) == pc.peer
+			return dp.(*serverPeer) == pc.peer
 		},
 		request: func(dp distPeer) func() {
 			reqID := genReqID()
-			peer := dp.(*peer)
-			cost := peer.GetRequestCost(GetBlockHeadersMsg, amount)
+			peer := dp.(*serverPeer)
+			cost := peer.getRequestCost(GetBlockHeadersMsg, amount)
 			peer.fcServer.QueuedRequest(reqID, cost)
-			return func() { peer.RequestHeadersByHash(reqID, cost, origin, amount, skip, reverse) }
+			return func() { peer.requestHeadersByHash(reqID, origin, amount, skip, reverse) }
 		},
 	}
 	_, ok := <-pc.handler.backend.reqDist.queue(rq)
@@ -364,18 +365,18 @@ func (pc *peerConnection) RequestHeadersByHash(origin common.Hash, amount int, s
 func (pc *peerConnection) RequestHeadersByNumber(origin uint64, amount int, skip int, reverse bool) error {
 	rq := &distReq{
 		getCost: func(dp distPeer) uint64 {
-			peer := dp.(*peer)
-			return peer.GetRequestCost(GetBlockHeadersMsg, amount)
+			peer := dp.(*serverPeer)
+			return peer.getRequestCost(GetBlockHeadersMsg, amount)
 		},
 		canSend: func(dp distPeer) bool {
-			return dp.(*peer) == pc.peer
+			return dp.(*serverPeer) == pc.peer
 		},
 		request: func(dp distPeer) func() {
 			reqID := genReqID()
-			peer := dp.(*peer)
-			cost := peer.GetRequestCost(GetBlockHeadersMsg, amount)
+			peer := dp.(*serverPeer)
+			cost := peer.getRequestCost(GetBlockHeadersMsg, amount)
 			peer.fcServer.QueuedRequest(reqID, cost)
-			return func() { peer.RequestHeadersByNumber(reqID, cost, origin, amount, skip, reverse) }
+			return func() { peer.requestHeadersByNumber(reqID, origin, amount, skip, reverse) }
 		},
 	}
 	_, ok := <-pc.handler.backend.reqDist.queue(rq)
@@ -388,7 +389,7 @@ func (pc *peerConnection) RequestHeadersByNumber(origin uint64, amount int, skip
 // downloaderPeerNotify implements peerSetNotify
 type downloaderPeerNotify clientHandler
 
-func (d *downloaderPeerNotify) registerPeer(p *peer) {
+func (d *downloaderPeerNotify) registerPeer(p *serverPeer) {
 	h := (*clientHandler)(d)
 	pc := &peerConnection{
 		handler: h,
@@ -397,7 +398,7 @@ func (d *downloaderPeerNotify) registerPeer(p *peer) {
 	h.downloader.RegisterLightPeer(p.id, ethVersion, pc)
 }
 
-func (d *downloaderPeerNotify) unregisterPeer(p *peer) {
+func (d *downloaderPeerNotify) unregisterPeer(p *serverPeer) {
 	h := (*clientHandler)(d)
 	h.downloader.UnregisterPeer(p.id)
 }
diff --git a/les/clientpool.go b/les/clientpool.go
index da76f08b91..b01c825a7a 100644
--- a/les/clientpool.go
+++ b/les/clientpool.go
@@ -97,12 +97,12 @@ type clientPool struct {
 	disableBias       bool           // Disable connection bias(used in testing)
 }
 
-// clientPeer represents a client in the pool.
+// clientPoolPeer represents a client peer in the pool.
 // Positive balances are assigned to node key while negative balances are assigned
 // to freeClientId. Currently network IP address without port is used because
 // clients have a limited access to IP addresses while new node keys can be easily
 // generated so it would be useless to assign a negative value to them.
-type clientPeer interface {
+type clientPoolPeer interface {
 	ID() enode.ID
 	freeClientId() string
 	updateCapacity(uint64)
@@ -117,7 +117,7 @@ type clientInfo struct {
 	capacity               uint64
 	priority               bool
 	pool                   *clientPool
-	peer                   clientPeer
+	peer                   clientPoolPeer
 	queueIndex             int // position in connectedQueue
 	balanceTracker         balanceTracker
 	posFactors, negFactors priceFactors
@@ -207,7 +207,7 @@ func (f *clientPool) stop() {
 
 // connect should be called after a successful handshake. If the connection was
 // rejected, there is no need to call disconnect.
-func (f *clientPool) connect(peer clientPeer, capacity uint64) bool {
+func (f *clientPool) connect(peer clientPoolPeer, capacity uint64) bool {
 	f.lock.Lock()
 	defer f.lock.Unlock()
 
@@ -322,7 +322,7 @@ func (f *clientPool) connect(peer clientPeer, capacity uint64) bool {
 // disconnect should be called when a connection is terminated. If the disconnection
 // was initiated by the pool itself using disconnectFn then calling disconnect is
 // not necessary but permitted.
-func (f *clientPool) disconnect(p clientPeer) {
+func (f *clientPool) disconnect(p clientPoolPeer) {
 	f.lock.Lock()
 	defer f.lock.Unlock()
 
@@ -516,7 +516,7 @@ func (f *clientPool) setCapacity(c *clientInfo, capacity uint64) error {
 }
 
 // requestCost feeds request cost after serving a request from the given peer.
-func (f *clientPool) requestCost(p *peer, cost uint64) {
+func (f *clientPool) requestCost(p *clientPeer, cost uint64) {
 	f.lock.Lock()
 	defer f.lock.Unlock()
 
diff --git a/les/commons.go b/les/commons.go
index b402c51769..29b5b7660e 100644
--- a/les/commons.go
+++ b/les/commons.go
@@ -61,7 +61,6 @@ type lesCommons struct {
 	chainConfig                  *params.ChainConfig
 	iConfig                      *light.IndexerConfig
 	chainDb                      ethdb.Database
-	peers                        *peerSet
 	chainReader                  chainReader
 	chtIndexer, bloomTrieIndexer *core.ChainIndexer
 	oracle                       *checkpointoracle.CheckpointOracle
diff --git a/les/distributor.go b/les/distributor.go
index 6d81149720..4d2be1b8f9 100644
--- a/les/distributor.go
+++ b/les/distributor.go
@@ -49,7 +49,7 @@ type requestDistributor struct {
 type distPeer interface {
 	waitBefore(uint64) (time.Duration, float64)
 	canQueue() bool
-	queueSend(f func())
+	queueSend(f func()) bool
 }
 
 // distReq is the request abstraction used by the distributor. It is based on
@@ -73,7 +73,7 @@ type distReq struct {
 }
 
 // newRequestDistributor creates a new request distributor
-func newRequestDistributor(peers *peerSet, clock mclock.Clock) *requestDistributor {
+func newRequestDistributor(peers *serverPeerSet, clock mclock.Clock) *requestDistributor {
 	d := &requestDistributor{
 		clock:    clock,
 		reqQueue: list.New(),
@@ -82,7 +82,7 @@ func newRequestDistributor(peers *peerSet, clock mclock.Clock) *requestDistribut
 		peers:    make(map[distPeer]struct{}),
 	}
 	if peers != nil {
-		peers.notify(d)
+		peers.subscribe(d)
 	}
 	d.wg.Add(1)
 	go d.loop()
@@ -90,14 +90,14 @@ func newRequestDistributor(peers *peerSet, clock mclock.Clock) *requestDistribut
 }
 
 // registerPeer implements peerSetNotify
-func (d *requestDistributor) registerPeer(p *peer) {
+func (d *requestDistributor) registerPeer(p *serverPeer) {
 	d.peerLock.Lock()
 	d.peers[p] = struct{}{}
 	d.peerLock.Unlock()
 }
 
 // unregisterPeer implements peerSetNotify
-func (d *requestDistributor) unregisterPeer(p *peer) {
+func (d *requestDistributor) unregisterPeer(p *serverPeer) {
 	d.peerLock.Lock()
 	delete(d.peers, p)
 	d.peerLock.Unlock()
diff --git a/les/distributor_test.go b/les/distributor_test.go
index 539c1aa7d7..9a93dba145 100644
--- a/les/distributor_test.go
+++ b/les/distributor_test.go
@@ -105,8 +105,9 @@ func (p *testDistPeer) canQueue() bool {
 	return true
 }
 
-func (p *testDistPeer) queueSend(f func()) {
+func (p *testDistPeer) queueSend(f func()) bool {
 	f()
+	return true
 }
 
 func TestRequestDistributor(t *testing.T) {
diff --git a/les/fetcher.go b/les/fetcher.go
index df76c56d70..7fa81cbcbb 100644
--- a/les/fetcher.go
+++ b/les/fetcher.go
@@ -45,10 +45,10 @@ type lightFetcher struct {
 
 	lock            sync.Mutex // lock protects access to the fetcher's internal state variables except sent requests
 	maxConfirmedTd  *big.Int
-	peers           map[*peer]*fetcherPeerInfo
+	peers           map[*serverPeer]*fetcherPeerInfo
 	lastUpdateStats *updateStatsEntry
 	syncing         bool
-	syncDone        chan *peer
+	syncDone        chan *serverPeer
 
 	reqMu             sync.RWMutex // reqMu protects access to sent header fetch requests
 	requested         map[uint64]fetchRequest
@@ -96,7 +96,7 @@ type fetcherTreeNode struct {
 type fetchRequest struct {
 	hash    common.Hash
 	amount  uint64
-	peer    *peer
+	peer    *serverPeer
 	sent    mclock.AbsTime
 	timeout bool
 }
@@ -105,7 +105,7 @@ type fetchRequest struct {
 type fetchResponse struct {
 	reqID   uint64
 	headers []*types.Header
-	peer    *peer
+	peer    *serverPeer
 }
 
 // newLightFetcher creates a new light fetcher
@@ -113,16 +113,16 @@ func newLightFetcher(h *clientHandler) *lightFetcher {
 	f := &lightFetcher{
 		handler:        h,
 		chain:          h.backend.blockchain,
-		peers:          make(map[*peer]*fetcherPeerInfo),
+		peers:          make(map[*serverPeer]*fetcherPeerInfo),
 		deliverChn:     make(chan fetchResponse, 100),
 		requested:      make(map[uint64]fetchRequest),
 		timeoutChn:     make(chan uint64),
 		requestTrigger: make(chan struct{}, 1),
-		syncDone:       make(chan *peer),
+		syncDone:       make(chan *serverPeer),
 		closeCh:        make(chan struct{}),
 		maxConfirmedTd: big.NewInt(0),
 	}
-	h.backend.peers.notify(f)
+	h.backend.peers.subscribe(f)
 
 	f.wg.Add(1)
 	go f.syncLoop()
@@ -222,7 +222,7 @@ func (f *lightFetcher) syncLoop() {
 }
 
 // registerPeer adds a new peer to the fetcher's peer set
-func (f *lightFetcher) registerPeer(p *peer) {
+func (f *lightFetcher) registerPeer(p *serverPeer) {
 	p.lock.Lock()
 	p.hasBlock = func(hash common.Hash, number uint64, hasState bool) bool {
 		return f.peerHasBlock(p, hash, number, hasState)
@@ -235,7 +235,7 @@ func (f *lightFetcher) registerPeer(p *peer) {
 }
 
 // unregisterPeer removes a new peer from the fetcher's peer set
-func (f *lightFetcher) unregisterPeer(p *peer) {
+func (f *lightFetcher) unregisterPeer(p *serverPeer) {
 	p.lock.Lock()
 	p.hasBlock = nil
 	p.lock.Unlock()
@@ -250,7 +250,7 @@ func (f *lightFetcher) unregisterPeer(p *peer) {
 
 // announce processes a new announcement message received from a peer, adding new
 // nodes to the peer's block tree and removing old nodes if necessary
-func (f *lightFetcher) announce(p *peer, head *announceData) {
+func (f *lightFetcher) announce(p *serverPeer, head *announceData) {
 	f.lock.Lock()
 	defer f.lock.Unlock()
 	p.Log().Debug("Received new announcement", "number", head.Number, "hash", head.Hash, "reorg", head.ReorgDepth)
@@ -346,7 +346,7 @@ func (f *lightFetcher) announce(p *peer, head *announceData) {
 
 	f.checkKnownNode(p, n)
 	p.lock.Lock()
-	p.headInfo = head
+	p.headInfo = blockInfo{Number: head.Number, Hash: head.Hash, Td: head.Td}
 	fp.lastAnnounced = n
 	p.lock.Unlock()
 	f.checkUpdateStats(p, nil)
@@ -358,7 +358,7 @@ func (f *lightFetcher) announce(p *peer, head *announceData) {
 
 // peerHasBlock returns true if we can assume the peer knows the given block
 // based on its announcements
-func (f *lightFetcher) peerHasBlock(p *peer, hash common.Hash, number uint64, hasState bool) bool {
+func (f *lightFetcher) peerHasBlock(p *serverPeer, hash common.Hash, number uint64, hasState bool) bool {
 	f.lock.Lock()
 	defer f.lock.Unlock()
 
@@ -395,7 +395,7 @@ func (f *lightFetcher) peerHasBlock(p *peer, hash common.Hash, number uint64, ha
 
 // requestAmount calculates the amount of headers to be downloaded starting
 // from a certain head backwards
-func (f *lightFetcher) requestAmount(p *peer, n *fetcherTreeNode) uint64 {
+func (f *lightFetcher) requestAmount(p *serverPeer, n *fetcherTreeNode) uint64 {
 	amount := uint64(0)
 	nn := n
 	for nn != nil && !f.checkKnownNode(p, nn) {
@@ -488,7 +488,7 @@ func (f *lightFetcher) newFetcherDistReqForSync(bestHash common.Hash) *distReq {
 			return 0
 		},
 		canSend: func(dp distPeer) bool {
-			p := dp.(*peer)
+			p := dp.(*serverPeer)
 			f.lock.Lock()
 			defer f.lock.Unlock()
 
@@ -504,7 +504,7 @@ func (f *lightFetcher) newFetcherDistReqForSync(bestHash common.Hash) *distReq {
 				f.setLastTrustedHeader(f.chain.CurrentHeader())
 			}
 			go func() {
-				p := dp.(*peer)
+				p := dp.(*serverPeer)
 				p.Log().Debug("Synchronisation started")
 				f.handler.synchronise(p)
 				f.syncDone <- p
@@ -518,11 +518,11 @@ func (f *lightFetcher) newFetcherDistReqForSync(bestHash common.Hash) *distReq {
 func (f *lightFetcher) newFetcherDistReq(bestHash common.Hash, reqID uint64, bestAmount uint64) *distReq {
 	return &distReq{
 		getCost: func(dp distPeer) uint64 {
-			p := dp.(*peer)
-			return p.GetRequestCost(GetBlockHeadersMsg, int(bestAmount))
+			p := dp.(*serverPeer)
+			return p.getRequestCost(GetBlockHeadersMsg, int(bestAmount))
 		},
 		canSend: func(dp distPeer) bool {
-			p := dp.(*peer)
+			p := dp.(*serverPeer)
 			f.lock.Lock()
 			defer f.lock.Unlock()
 
@@ -537,7 +537,7 @@ func (f *lightFetcher) newFetcherDistReq(bestHash common.Hash, reqID uint64, bes
 			return n != nil && !n.requested
 		},
 		request: func(dp distPeer) func() {
-			p := dp.(*peer)
+			p := dp.(*serverPeer)
 			f.lock.Lock()
 			fp := f.peers[p]
 			if fp != nil {
@@ -548,7 +548,7 @@ func (f *lightFetcher) newFetcherDistReq(bestHash common.Hash, reqID uint64, bes
 			}
 			f.lock.Unlock()
 
-			cost := p.GetRequestCost(GetBlockHeadersMsg, int(bestAmount))
+			cost := p.getRequestCost(GetBlockHeadersMsg, int(bestAmount))
 			p.fcServer.QueuedRequest(reqID, cost)
 			f.reqMu.Lock()
 			f.requested[reqID] = fetchRequest{hash: bestHash, amount: bestAmount, peer: p, sent: mclock.Now()}
@@ -557,13 +557,13 @@ func (f *lightFetcher) newFetcherDistReq(bestHash common.Hash, reqID uint64, bes
 				time.Sleep(hardRequestTimeout)
 				f.timeoutChn <- reqID
 			}()
-			return func() { p.RequestHeadersByHash(reqID, cost, bestHash, int(bestAmount), 0, true) }
+			return func() { p.requestHeadersByHash(reqID, bestHash, int(bestAmount), 0, true) }
 		},
 	}
 }
 
 // deliverHeaders delivers header download request responses for processing
-func (f *lightFetcher) deliverHeaders(peer *peer, reqID uint64, headers []*types.Header) {
+func (f *lightFetcher) deliverHeaders(peer *serverPeer, reqID uint64, headers []*types.Header) {
 	f.deliverChn <- fetchResponse{reqID: reqID, headers: headers, peer: peer}
 }
 
@@ -694,7 +694,7 @@ func (f *lightFetcher) checkAnnouncedHeaders(fp *fetcherPeerInfo, headers []*typ
 // checkSyncedHeaders updates peer's block tree after synchronisation by marking
 // downloaded headers as known. If none of the announced headers are found after
 // syncing, the peer is dropped.
-func (f *lightFetcher) checkSyncedHeaders(p *peer) {
+func (f *lightFetcher) checkSyncedHeaders(p *serverPeer) {
 	fp := f.peers[p]
 	if fp == nil {
 		p.Log().Debug("Unknown peer to check sync headers")
@@ -728,7 +728,7 @@ func (f *lightFetcher) checkSyncedHeaders(p *peer) {
 }
 
 // lastTrustedTreeNode return last approved treeNode and a list of unapproved hashes
-func (f *lightFetcher) lastTrustedTreeNode(p *peer) (*types.Header, []common.Hash) {
+func (f *lightFetcher) lastTrustedTreeNode(p *serverPeer) (*types.Header, []common.Hash) {
 	unapprovedHashes := make([]common.Hash, 0)
 	current := f.chain.CurrentHeader()
 
@@ -764,7 +764,7 @@ func (f *lightFetcher) setLastTrustedHeader(h *types.Header) {
 
 // checkKnownNode checks if a block tree node is known (downloaded and validated)
 // If it was not known previously but found in the database, sets its known flag
-func (f *lightFetcher) checkKnownNode(p *peer, n *fetcherTreeNode) bool {
+func (f *lightFetcher) checkKnownNode(p *serverPeer, n *fetcherTreeNode) bool {
 	if n.known {
 		return true
 	}
@@ -867,7 +867,7 @@ func (f *lightFetcher) updateMaxConfirmedTd(td *big.Int) {
 // If a new entry has been added to the global tail, it is passed as a parameter here even though this function
 // assumes that it has already been added, so that if the peer's list is empty (all heads confirmed, head is nil),
 // it can set the new head to newEntry.
-func (f *lightFetcher) checkUpdateStats(p *peer, newEntry *updateStatsEntry) {
+func (f *lightFetcher) checkUpdateStats(p *serverPeer, newEntry *updateStatsEntry) {
 	now := mclock.Now()
 	fp := f.peers[p]
 	if fp == nil {
diff --git a/les/handler_test.go b/les/handler_test.go
index aad8d18e45..1612caf427 100644
--- a/les/handler_test.go
+++ b/les/handler_test.go
@@ -168,8 +168,7 @@ func testGetBlockHeaders(t *testing.T, protocol int) {
 		// Send the hash request and verify the response
 		reqID++
 
-		cost := server.peer.peer.GetRequestCost(GetBlockHeadersMsg, int(tt.query.Amount))
-		sendRequest(server.peer.app, GetBlockHeadersMsg, reqID, cost, tt.query)
+		sendRequest(server.peer.app, GetBlockHeadersMsg, reqID, tt.query)
 		if err := expectResponse(server.peer.app, BlockHeadersMsg, reqID, testBufLimit, headers); err != nil {
 			t.Errorf("test %d: headers mismatch: %v", i, err)
 		}
@@ -246,8 +245,7 @@ func testGetBlockBodies(t *testing.T, protocol int) {
 		reqID++
 
 		// Send the hash request and verify the response
-		cost := server.peer.peer.GetRequestCost(GetBlockBodiesMsg, len(hashes))
-		sendRequest(server.peer.app, GetBlockBodiesMsg, reqID, cost, hashes)
+		sendRequest(server.peer.app, GetBlockBodiesMsg, reqID, hashes)
 		if err := expectResponse(server.peer.app, BlockBodiesMsg, reqID, testBufLimit, bodies); err != nil {
 			t.Errorf("test %d: bodies mismatch: %v", i, err)
 		}
@@ -278,8 +276,7 @@ func testGetCode(t *testing.T, protocol int) {
 		}
 	}
 
-	cost := server.peer.peer.GetRequestCost(GetCodeMsg, len(codereqs))
-	sendRequest(server.peer.app, GetCodeMsg, 42, cost, codereqs)
+	sendRequest(server.peer.app, GetCodeMsg, 42, codereqs)
 	if err := expectResponse(server.peer.app, CodeMsg, 42, testBufLimit, codes); err != nil {
 		t.Errorf("codes mismatch: %v", err)
 	}
@@ -299,8 +296,7 @@ func testGetStaleCode(t *testing.T, protocol int) {
 			BHash:  bc.GetHeaderByNumber(number).Hash(),
 			AccKey: crypto.Keccak256(testContractAddr[:]),
 		}
-		cost := server.peer.peer.GetRequestCost(GetCodeMsg, 1)
-		sendRequest(server.peer.app, GetCodeMsg, 42, cost, []*CodeReq{req})
+		sendRequest(server.peer.app, GetCodeMsg, 42, []*CodeReq{req})
 		if err := expectResponse(server.peer.app, CodeMsg, 42, testBufLimit, expected); err != nil {
 			t.Errorf("codes mismatch: %v", err)
 		}
@@ -331,8 +327,7 @@ func testGetReceipt(t *testing.T, protocol int) {
 		receipts = append(receipts, rawdb.ReadRawReceipts(server.db, block.Hash(), block.NumberU64()))
 	}
 	// Send the hash request and verify the response
-	cost := server.peer.peer.GetRequestCost(GetReceiptsMsg, len(hashes))
-	sendRequest(server.peer.app, GetReceiptsMsg, 42, cost, hashes)
+	sendRequest(server.peer.app, GetReceiptsMsg, 42, hashes)
 	if err := expectResponse(server.peer.app, ReceiptsMsg, 42, testBufLimit, receipts); err != nil {
 		t.Errorf("receipts mismatch: %v", err)
 	}
@@ -367,8 +362,7 @@ func testGetProofs(t *testing.T, protocol int) {
 		}
 	}
 	// Send the proof request and verify the response
-	cost := server.peer.peer.GetRequestCost(GetProofsV2Msg, len(proofreqs))
-	sendRequest(server.peer.app, GetProofsV2Msg, 42, cost, proofreqs)
+	sendRequest(server.peer.app, GetProofsV2Msg, 42, proofreqs)
 	if err := expectResponse(server.peer.app, ProofsV2Msg, 42, testBufLimit, proofsV2.NodeList()); err != nil {
 		t.Errorf("proofs mismatch: %v", err)
 	}
@@ -392,8 +386,7 @@ func testGetStaleProof(t *testing.T, protocol int) {
 			BHash: header.Hash(),
 			Key:   account,
 		}
-		cost := server.peer.peer.GetRequestCost(GetProofsV2Msg, 1)
-		sendRequest(server.peer.app, GetProofsV2Msg, 42, cost, []*ProofReq{req})
+		sendRequest(server.peer.app, GetProofsV2Msg, 42, []*ProofReq{req})
 
 		var expected []rlp.RawValue
 		if wantOK {
@@ -453,8 +446,7 @@ func testGetCHTProofs(t *testing.T, protocol int) {
 		AuxReq:  auxHeader,
 	}}
 	// Send the proof request and verify the response
-	cost := server.peer.peer.GetRequestCost(GetHelperTrieProofsMsg, len(requestsV2))
-	sendRequest(server.peer.app, GetHelperTrieProofsMsg, 42, cost, requestsV2)
+	sendRequest(server.peer.app, GetHelperTrieProofsMsg, 42, requestsV2)
 	if err := expectResponse(server.peer.app, HelperTrieProofsMsg, 42, testBufLimit, proofsV2); err != nil {
 		t.Errorf("proofs mismatch: %v", err)
 	}
@@ -502,8 +494,7 @@ func testGetBloombitsProofs(t *testing.T, protocol int) {
 		trie.Prove(key, 0, &proofs.Proofs)
 
 		// Send the proof request and verify the response
-		cost := server.peer.peer.GetRequestCost(GetHelperTrieProofsMsg, len(requests))
-		sendRequest(server.peer.app, GetHelperTrieProofsMsg, 42, cost, requests)
+		sendRequest(server.peer.app, GetHelperTrieProofsMsg, 42, requests)
 		if err := expectResponse(server.peer.app, HelperTrieProofsMsg, 42, testBufLimit, proofs); err != nil {
 			t.Errorf("bit %d: proofs mismatch: %v", bit, err)
 		}
@@ -525,11 +516,9 @@ func testTransactionStatus(t *testing.T, protocol int) {
 	test := func(tx *types.Transaction, send bool, expStatus light.TxStatus) {
 		reqID++
 		if send {
-			cost := server.peer.peer.GetRequestCost(SendTxV2Msg, 1)
-			sendRequest(server.peer.app, SendTxV2Msg, reqID, cost, types.Transactions{tx})
+			sendRequest(server.peer.app, SendTxV2Msg, reqID, types.Transactions{tx})
 		} else {
-			cost := server.peer.peer.GetRequestCost(GetTxStatusMsg, 1)
-			sendRequest(server.peer.app, GetTxStatusMsg, reqID, cost, []common.Hash{tx.Hash()})
+			sendRequest(server.peer.app, GetTxStatusMsg, reqID, []common.Hash{tx.Hash()})
 		}
 		if err := expectResponse(server.peer.app, TxStatusMsg, reqID, testBufLimit, []light.TxStatus{expStatus}); err != nil {
 			t.Errorf("transaction status mismatch")
@@ -620,7 +609,7 @@ func TestStopResumeLes3(t *testing.T) {
 	header := server.handler.blockchain.CurrentHeader()
 	req := func() {
 		reqID++
-		sendRequest(server.peer.app, GetBlockHeadersMsg, reqID, testCost, &getBlockHeadersData{Origin: hashOrNumber{Hash: header.Hash()}, Amount: 1})
+		sendRequest(server.peer.app, GetBlockHeadersMsg, reqID, &getBlockHeadersData{Origin: hashOrNumber{Hash: header.Hash()}, Amount: 1})
 	}
 	for i := 1; i <= 5; i++ {
 		// send requests while we still have enough buffer and expect a response
diff --git a/les/odr.go b/les/odr.go
index 136ecf4df4..f8469cc103 100644
--- a/les/odr.go
+++ b/les/odr.go
@@ -106,17 +106,17 @@ func (odr *LesOdr) Retrieve(ctx context.Context, req light.OdrRequest) (err erro
 	reqID := genReqID()
 	rq := &distReq{
 		getCost: func(dp distPeer) uint64 {
-			return lreq.GetCost(dp.(*peer))
+			return lreq.GetCost(dp.(*serverPeer))
 		},
 		canSend: func(dp distPeer) bool {
-			p := dp.(*peer)
+			p := dp.(*serverPeer)
 			if !p.onlyAnnounce {
 				return lreq.CanSend(p)
 			}
 			return false
 		},
 		request: func(dp distPeer) func() {
-			p := dp.(*peer)
+			p := dp.(*serverPeer)
 			cost := lreq.GetCost(p)
 			p.fcServer.QueuedRequest(reqID, cost)
 			return func() { lreq.Request(reqID, p) }
diff --git a/les/odr_requests.go b/les/odr_requests.go
index 3c4dd7090f..146da2213c 100644
--- a/les/odr_requests.go
+++ b/les/odr_requests.go
@@ -46,9 +46,9 @@ var (
 )
 
 type LesOdrRequest interface {
-	GetCost(*peer) uint64
-	CanSend(*peer) bool
-	Request(uint64, *peer) error
+	GetCost(*serverPeer) uint64
+	CanSend(*serverPeer) bool
+	Request(uint64, *serverPeer) error
 	Validate(ethdb.Database, *Msg) error
 }
 
@@ -78,19 +78,19 @@ type BlockRequest light.BlockRequest
 
 // GetCost returns the cost of the given ODR request according to the serving
 // peer's cost table (implementation of LesOdrRequest)
-func (r *BlockRequest) GetCost(peer *peer) uint64 {
-	return peer.GetRequestCost(GetBlockBodiesMsg, 1)
+func (r *BlockRequest) GetCost(peer *serverPeer) uint64 {
+	return peer.getRequestCost(GetBlockBodiesMsg, 1)
 }
 
 // CanSend tells if a certain peer is suitable for serving the given request
-func (r *BlockRequest) CanSend(peer *peer) bool {
+func (r *BlockRequest) CanSend(peer *serverPeer) bool {
 	return peer.HasBlock(r.Hash, r.Number, false)
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
-func (r *BlockRequest) Request(reqID uint64, peer *peer) error {
+func (r *BlockRequest) Request(reqID uint64, peer *serverPeer) error {
 	peer.Log().Debug("Requesting block body", "hash", r.Hash)
-	return peer.RequestBodies(reqID, r.GetCost(peer), []common.Hash{r.Hash})
+	return peer.requestBodies(reqID, []common.Hash{r.Hash})
 }
 
 // Valid processes an ODR request reply message from the LES network
@@ -134,19 +134,19 @@ type ReceiptsRequest light.ReceiptsRequest
 
 // GetCost returns the cost of the given ODR request according to the serving
 // peer's cost table (implementation of LesOdrRequest)
-func (r *ReceiptsRequest) GetCost(peer *peer) uint64 {
-	return peer.GetRequestCost(GetReceiptsMsg, 1)
+func (r *ReceiptsRequest) GetCost(peer *serverPeer) uint64 {
+	return peer.getRequestCost(GetReceiptsMsg, 1)
 }
 
 // CanSend tells if a certain peer is suitable for serving the given request
-func (r *ReceiptsRequest) CanSend(peer *peer) bool {
+func (r *ReceiptsRequest) CanSend(peer *serverPeer) bool {
 	return peer.HasBlock(r.Hash, r.Number, false)
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
-func (r *ReceiptsRequest) Request(reqID uint64, peer *peer) error {
+func (r *ReceiptsRequest) Request(reqID uint64, peer *serverPeer) error {
 	peer.Log().Debug("Requesting block receipts", "hash", r.Hash)
-	return peer.RequestReceipts(reqID, r.GetCost(peer), []common.Hash{r.Hash})
+	return peer.requestReceipts(reqID, []common.Hash{r.Hash})
 }
 
 // Valid processes an ODR request reply message from the LES network
@@ -191,24 +191,24 @@ type TrieRequest light.TrieRequest
 
 // GetCost returns the cost of the given ODR request according to the serving
 // peer's cost table (implementation of LesOdrRequest)
-func (r *TrieRequest) GetCost(peer *peer) uint64 {
-	return peer.GetRequestCost(GetProofsV2Msg, 1)
+func (r *TrieRequest) GetCost(peer *serverPeer) uint64 {
+	return peer.getRequestCost(GetProofsV2Msg, 1)
 }
 
 // CanSend tells if a certain peer is suitable for serving the given request
-func (r *TrieRequest) CanSend(peer *peer) bool {
+func (r *TrieRequest) CanSend(peer *serverPeer) bool {
 	return peer.HasBlock(r.Id.BlockHash, r.Id.BlockNumber, true)
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
-func (r *TrieRequest) Request(reqID uint64, peer *peer) error {
+func (r *TrieRequest) Request(reqID uint64, peer *serverPeer) error {
 	peer.Log().Debug("Requesting trie proof", "root", r.Id.Root, "key", r.Key)
 	req := ProofReq{
 		BHash:  r.Id.BlockHash,
 		AccKey: r.Id.AccKey,
 		Key:    r.Key,
 	}
-	return peer.RequestProofs(reqID, r.GetCost(peer), []ProofReq{req})
+	return peer.requestProofs(reqID, []ProofReq{req})
 }
 
 // Valid processes an ODR request reply message from the LES network
@@ -245,23 +245,23 @@ type CodeRequest light.CodeRequest
 
 // GetCost returns the cost of the given ODR request according to the serving
 // peer's cost table (implementation of LesOdrRequest)
-func (r *CodeRequest) GetCost(peer *peer) uint64 {
-	return peer.GetRequestCost(GetCodeMsg, 1)
+func (r *CodeRequest) GetCost(peer *serverPeer) uint64 {
+	return peer.getRequestCost(GetCodeMsg, 1)
 }
 
 // CanSend tells if a certain peer is suitable for serving the given request
-func (r *CodeRequest) CanSend(peer *peer) bool {
+func (r *CodeRequest) CanSend(peer *serverPeer) bool {
 	return peer.HasBlock(r.Id.BlockHash, r.Id.BlockNumber, true)
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
-func (r *CodeRequest) Request(reqID uint64, peer *peer) error {
+func (r *CodeRequest) Request(reqID uint64, peer *serverPeer) error {
 	peer.Log().Debug("Requesting code data", "hash", r.Hash)
 	req := CodeReq{
 		BHash:  r.Id.BlockHash,
 		AccKey: r.Id.AccKey,
 	}
-	return peer.RequestCode(reqID, r.GetCost(peer), []CodeReq{req})
+	return peer.requestCode(reqID, []CodeReq{req})
 }
 
 // Valid processes an ODR request reply message from the LES network
@@ -316,12 +316,12 @@ type ChtRequest light.ChtRequest
 
 // GetCost returns the cost of the given ODR request according to the serving
 // peer's cost table (implementation of LesOdrRequest)
-func (r *ChtRequest) GetCost(peer *peer) uint64 {
-	return peer.GetRequestCost(GetHelperTrieProofsMsg, 1)
+func (r *ChtRequest) GetCost(peer *serverPeer) uint64 {
+	return peer.getRequestCost(GetHelperTrieProofsMsg, 1)
 }
 
 // CanSend tells if a certain peer is suitable for serving the given request
-func (r *ChtRequest) CanSend(peer *peer) bool {
+func (r *ChtRequest) CanSend(peer *serverPeer) bool {
 	peer.lock.RLock()
 	defer peer.lock.RUnlock()
 
@@ -333,7 +333,7 @@ func (r *ChtRequest) CanSend(peer *peer) bool {
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
-func (r *ChtRequest) Request(reqID uint64, peer *peer) error {
+func (r *ChtRequest) Request(reqID uint64, peer *serverPeer) error {
 	peer.Log().Debug("Requesting CHT", "cht", r.ChtNum, "block", r.BlockNum)
 	var encNum [8]byte
 	binary.BigEndian.PutUint64(encNum[:], r.BlockNum)
@@ -343,7 +343,7 @@ func (r *ChtRequest) Request(reqID uint64, peer *peer) error {
 		Key:     encNum[:],
 		AuxReq:  auxHeader,
 	}
-	return peer.RequestHelperTrieProofs(reqID, r.GetCost(peer), []HelperTrieReq{req})
+	return peer.requestHelperTrieProofs(reqID, []HelperTrieReq{req})
 }
 
 // Valid processes an ODR request reply message from the LES network
@@ -413,12 +413,12 @@ type BloomRequest light.BloomRequest
 
 // GetCost returns the cost of the given ODR request according to the serving
 // peer's cost table (implementation of LesOdrRequest)
-func (r *BloomRequest) GetCost(peer *peer) uint64 {
-	return peer.GetRequestCost(GetHelperTrieProofsMsg, len(r.SectionIndexList))
+func (r *BloomRequest) GetCost(peer *serverPeer) uint64 {
+	return peer.getRequestCost(GetHelperTrieProofsMsg, len(r.SectionIndexList))
 }
 
 // CanSend tells if a certain peer is suitable for serving the given request
-func (r *BloomRequest) CanSend(peer *peer) bool {
+func (r *BloomRequest) CanSend(peer *serverPeer) bool {
 	peer.lock.RLock()
 	defer peer.lock.RUnlock()
 
@@ -429,7 +429,7 @@ func (r *BloomRequest) CanSend(peer *peer) bool {
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
-func (r *BloomRequest) Request(reqID uint64, peer *peer) error {
+func (r *BloomRequest) Request(reqID uint64, peer *serverPeer) error {
 	peer.Log().Debug("Requesting BloomBits", "bloomTrie", r.BloomTrieNum, "bitIdx", r.BitIdx, "sections", r.SectionIndexList)
 	reqs := make([]HelperTrieReq, len(r.SectionIndexList))
 
@@ -444,7 +444,7 @@ func (r *BloomRequest) Request(reqID uint64, peer *peer) error {
 			Key:     common.CopyBytes(encNumber[:]),
 		}
 	}
-	return peer.RequestHelperTrieProofs(reqID, r.GetCost(peer), reqs)
+	return peer.requestHelperTrieProofs(reqID, reqs)
 }
 
 // Valid processes an ODR request reply message from the LES network
@@ -489,19 +489,19 @@ type TxStatusRequest light.TxStatusRequest
 
 // GetCost returns the cost of the given ODR request according to the serving
 // peer's cost table (implementation of LesOdrRequest)
-func (r *TxStatusRequest) GetCost(peer *peer) uint64 {
-	return peer.GetRequestCost(GetTxStatusMsg, len(r.Hashes))
+func (r *TxStatusRequest) GetCost(peer *serverPeer) uint64 {
+	return peer.getRequestCost(GetTxStatusMsg, len(r.Hashes))
 }
 
 // CanSend tells if a certain peer is suitable for serving the given request
-func (r *TxStatusRequest) CanSend(peer *peer) bool {
+func (r *TxStatusRequest) CanSend(peer *serverPeer) bool {
 	return peer.version >= lpv2
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
-func (r *TxStatusRequest) Request(reqID uint64, peer *peer) error {
+func (r *TxStatusRequest) Request(reqID uint64, peer *serverPeer) error {
 	peer.Log().Debug("Requesting transaction status", "count", len(r.Hashes))
-	return peer.RequestTxStatus(reqID, r.GetCost(peer), r.Hashes)
+	return peer.requestTxStatus(reqID, r.Hashes)
 }
 
 // Valid processes an ODR request reply message from the LES network
diff --git a/les/odr_test.go b/les/odr_test.go
index 7d10878226..bbe439dfec 100644
--- a/les/odr_test.go
+++ b/les/odr_test.go
@@ -186,7 +186,7 @@ func testOdr(t *testing.T, protocol int, expFail uint64, checkCached bool, fn od
 	server, client, tearDown := newClientServerEnv(t, 4, protocol, nil, nil, 0, false, true)
 	defer tearDown()
 
-	client.handler.synchronise(client.peer.peer)
+	client.handler.synchronise(client.peer.speer)
 
 	// Ensure the client has synced all necessary data.
 	clientHead := client.handler.backend.blockchain.CurrentHeader()
@@ -224,19 +224,19 @@ func testOdr(t *testing.T, protocol int, expFail uint64, checkCached bool, fn od
 
 	// expect retrievals to fail (except genesis block) without a les peer
 	client.handler.backend.peers.lock.Lock()
-	client.peer.peer.hasBlock = func(common.Hash, uint64, bool) bool { return false }
+	client.peer.speer.hasBlock = func(common.Hash, uint64, bool) bool { return false }
 	client.handler.backend.peers.lock.Unlock()
 	test(expFail)
 
 	// expect all retrievals to pass
 	client.handler.backend.peers.lock.Lock()
-	client.peer.peer.hasBlock = func(common.Hash, uint64, bool) bool { return true }
+	client.peer.speer.hasBlock = func(common.Hash, uint64, bool) bool { return true }
 	client.handler.backend.peers.lock.Unlock()
 	test(5)
 
 	// still expect all retrievals to pass, now data should be cached locally
 	if checkCached {
-		client.handler.backend.peers.Unregister(client.peer.peer.id)
+		client.handler.backend.peers.unregister(client.peer.speer.id)
 		time.Sleep(time.Millisecond * 10) // ensure that all peerSetNotify callbacks are executed
 		test(5)
 	}
diff --git a/les/peer.go b/les/peer.go
index feb3910beb..28ec201bc9 100644
--- a/les/peer.go
+++ b/les/peer.go
@@ -48,24 +48,25 @@ var (
 const (
 	maxRequestErrors  = 20 // number of invalid requests tolerated (makes the protocol less brittle but still avoids spam)
 	maxResponseErrors = 50 // number of invalid responses tolerated (makes the protocol less brittle but still avoids spam)
-)
 
-// capacity limitation for parameter updates
-const (
 	allowedUpdateBytes = 100000                // initial/maximum allowed update size
 	allowedUpdateRate  = time.Millisecond * 10 // time constant for recharging one byte of allowance
-)
 
-const (
 	freezeTimeBase    = time.Millisecond * 700 // fixed component of client freeze time
 	freezeTimeRandom  = time.Millisecond * 600 // random component of client freeze time
 	freezeCheckPeriod = time.Millisecond * 100 // buffer value recheck period after initial freeze time has elapsed
-)
 
-// if the total encoded size of a sent transaction batch is over txSizeCostLimit
-// per transaction then the request cost is calculated as proportional to the
-// encoded size instead of the transaction count
-const txSizeCostLimit = 0x4000
+	// If the total encoded size of a sent transaction batch is over txSizeCostLimit
+	// per transaction then the request cost is calculated as proportional to the
+	// encoded size instead of the transaction count
+	txSizeCostLimit = 0x4000
+
+	// handshakeTimeout is the timeout LES handshake will be treated as failed.
+	handshakeTimeout = 5 * time.Second
+
+	// retrySendCachePeriod is the time interval a caching retry is performed.
+	retrySendCachePeriod = time.Millisecond * 100
+)
 
 const (
 	announceTypeNone = iota
@@ -73,62 +74,46 @@ const (
 	announceTypeSigned
 )
 
-type peer struct {
-	*p2p.Peer
-	rw p2p.MsgReadWriter
-
-	version int    // Protocol version negotiated
-	network uint64 // Network ID being on
-
-	announceType uint64
-
-	// Checkpoint relative fields
-	checkpoint       params.TrustedCheckpoint
-	checkpointNumber uint64
-
-	id string
+type keyValueEntry struct {
+	Key   string
+	Value rlp.RawValue
+}
 
-	headInfo *announceData
-	lock     sync.RWMutex
+type keyValueList []keyValueEntry
+type keyValueMap map[string]rlp.RawValue
 
-	sendQueue *execQueue
+func (l keyValueList) add(key string, val interface{}) keyValueList {
+	var entry keyValueEntry
+	entry.Key = key
+	if val == nil {
+		val = uint64(0)
+	}
+	enc, err := rlp.EncodeToBytes(val)
+	if err == nil {
+		entry.Value = enc
+	}
+	return append(l, entry)
+}
 
-	errCh chan error
+func (l keyValueList) decode() (keyValueMap, uint64) {
+	m := make(keyValueMap)
+	var size uint64
+	for _, entry := range l {
+		m[entry.Key] = entry.Value
+		size += uint64(len(entry.Key)) + uint64(len(entry.Value)) + 8
+	}
+	return m, size
+}
 
-	// responseLock ensures that responses are queued in the same order as
-	// RequestProcessed is called
-	responseLock  sync.Mutex
-	responseCount uint64
-	invalidCount  uint32
-
-	poolEntry      *poolEntry
-	hasBlock       func(common.Hash, uint64, bool) bool
-	responseErrors int
-	updateCounter  uint64
-	updateTime     mclock.AbsTime
-	frozen         uint32 // 1 if client is in frozen state
-
-	fcClient *flowcontrol.ClientNode // nil if the peer is server only
-	fcServer *flowcontrol.ServerNode // nil if the peer is client only
-	fcParams flowcontrol.ServerParams
-	fcCosts  requestCostTable
-
-	trusted, server         bool
-	onlyAnnounce            bool
-	chainSince, chainRecent uint64
-	stateSince, stateRecent uint64
-}
-
-func newPeer(version int, network uint64, trusted bool, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
-	return &peer{
-		Peer:    p,
-		rw:      rw,
-		version: version,
-		network: network,
-		id:      peerIdToString(p.ID()),
-		trusted: trusted,
-		errCh:   make(chan error, 1),
+func (m keyValueMap) get(key string, val interface{}) error {
+	enc, ok := m[key]
+	if !ok {
+		return errResp(ErrMissingKey, "%s", key)
+	}
+	if val == nil {
+		return nil
 	}
+	return rlp.DecodeBytes(enc, val)
 }
 
 // peerIdToString converts enode.ID to a string form
@@ -136,103 +121,71 @@ func peerIdToString(id enode.ID) string {
 	return fmt.Sprintf("%x", id.Bytes())
 }
 
-// freeClientId returns a string identifier for the peer. Multiple peers with the
-// same identifier can not be connected in free mode simultaneously.
-func (p *peer) freeClientId() string {
-	if addr, ok := p.RemoteAddr().(*net.TCPAddr); ok {
-		if addr.IP.IsLoopback() {
-			// using peer id instead of loopback ip address allows multiple free
-			// connections from local machine to own server
-			return p.id
-		} else {
-			return addr.IP.String()
-		}
-	}
-	return p.id
-}
+// peerCommons contains fields needed by both server peer and client peer.
+type peerCommons struct {
+	*p2p.Peer
+	rw p2p.MsgReadWriter
 
-// rejectUpdate returns true if a parameter update has to be rejected because
-// the size and/or rate of updates exceed the capacity limitation
-func (p *peer) rejectUpdate(size uint64) bool {
-	now := mclock.Now()
-	if p.updateCounter == 0 {
-		p.updateTime = now
-	} else {
-		dt := now - p.updateTime
-		r := uint64(dt / mclock.AbsTime(allowedUpdateRate))
-		if p.updateCounter > r {
-			p.updateCounter -= r
-			p.updateTime += mclock.AbsTime(allowedUpdateRate * time.Duration(r))
-		} else {
-			p.updateCounter = 0
-			p.updateTime = now
-		}
-	}
-	p.updateCounter += size
-	return p.updateCounter > allowedUpdateBytes
-}
+	id           string    // Peer identity.
+	version      int       // Protocol version negotiated.
+	network      uint64    // Network ID being on.
+	frozen       uint32    // Flag whether the peer is frozen.
+	announceType uint64    // New block announcement type.
+	headInfo     blockInfo // Latest block information.
 
-// freezeClient temporarily puts the client in a frozen state which means all
-// unprocessed and subsequent requests are dropped. Unfreezing happens automatically
-// after a short time if the client's buffer value is at least in the slightly positive
-// region. The client is also notified about being frozen/unfrozen with a Stop/Resume
-// message.
-func (p *peer) freezeClient() {
-	if p.version < lpv3 {
-		// if Stop/Resume is not supported then just drop the peer after setting
-		// its frozen status permanently
-		atomic.StoreUint32(&p.frozen, 1)
-		p.Peer.Disconnect(p2p.DiscUselessPeer)
-		return
-	}
-	if atomic.SwapUint32(&p.frozen, 1) == 0 {
-		go func() {
-			p.SendStop()
-			time.Sleep(freezeTimeBase + time.Duration(rand.Int63n(int64(freezeTimeRandom))))
-			for {
-				bufValue, bufLimit := p.fcClient.BufferStatus()
-				if bufLimit == 0 {
-					return
-				}
-				if bufValue <= bufLimit/8 {
-					time.Sleep(freezeCheckPeriod)
-				} else {
-					atomic.StoreUint32(&p.frozen, 0)
-					p.SendResume(bufValue)
-					break
-				}
-			}
-		}()
-	}
-}
+	// Background task queue for caching peer tasks and executing in order.
+	sendQueue *execQueue
 
-// freezeServer processes Stop/Resume messages from the given server
-func (p *peer) freezeServer(frozen bool) {
-	var f uint32
-	if frozen {
-		f = 1
-	}
-	if atomic.SwapUint32(&p.frozen, f) != f && frozen {
-		p.sendQueue.clear()
-	}
+	// Flow control agreement.
+	fcParams flowcontrol.ServerParams // The config for token bucket.
+	fcCosts  requestCostTable         // The Maximum request cost table.
+
+	closeCh chan struct{}
+	lock    sync.RWMutex // Lock used to protect all thread-sensitive fields.
 }
 
 // isFrozen returns true if the client is frozen or the server has put our
 // client in frozen state
-func (p *peer) isFrozen() bool {
+func (p *peerCommons) isFrozen() bool {
 	return atomic.LoadUint32(&p.frozen) != 0
 }
 
-func (p *peer) canQueue() bool {
+// canQueue returns an indicator whether the peer can queue a operation.
+func (p *peerCommons) canQueue() bool {
 	return p.sendQueue.canQueue() && !p.isFrozen()
 }
 
-func (p *peer) queueSend(f func()) {
-	p.sendQueue.queue(f)
+// queueSend caches a peer operation in the background task queue.
+// Please ensure to check `canQueue` before call this function
+func (p *peerCommons) queueSend(f func()) bool {
+	return p.sendQueue.queue(f)
+}
+
+// mustQueueSend starts a for loop and retry the caching if failed.
+// If the stopCh is closed, then it returns.
+func (p *peerCommons) mustQueueSend(f func()) {
+	for {
+		// Check whether the stopCh is closed.
+		select {
+		case <-p.closeCh:
+			return
+		default:
+		}
+		// If the function is successfully cached, return.
+		if p.canQueue() && p.queueSend(f) {
+			return
+		}
+		time.Sleep(retrySendCachePeriod)
+	}
+}
+
+// String implements fmt.Stringer.
+func (p *peerCommons) String() string {
+	return fmt.Sprintf("Peer %s [%s]", p.id, fmt.Sprintf("les/%d", p.version))
 }
 
 // Info gathers and returns a collection of metadata known about a peer.
-func (p *peer) Info() *eth.PeerInfo {
+func (p *peerCommons) Info() *eth.PeerInfo {
 	return &eth.PeerInfo{
 		Version:    p.version,
 		Difficulty: p.Td(),
@@ -241,62 +194,231 @@ func (p *peer) Info() *eth.PeerInfo {
 }
 
 // Head retrieves a copy of the current head (most recent) hash of the peer.
-func (p *peer) Head() (hash common.Hash) {
+func (p *peerCommons) Head() (hash common.Hash) {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 
-	copy(hash[:], p.headInfo.Hash[:])
-	return hash
+	return p.headInfo.Hash
 }
 
-func (p *peer) HeadAndTd() (hash common.Hash, td *big.Int) {
+// Td retrieves the current total difficulty of a peer.
+func (p *peerCommons) Td() *big.Int {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 
-	copy(hash[:], p.headInfo.Hash[:])
-	return hash, p.headInfo.Td
+	return new(big.Int).Set(p.headInfo.Td)
 }
 
-func (p *peer) headBlockInfo() blockInfo {
+// HeadAndTd retrieves the current head hash and total difficulty of a peer.
+func (p *peerCommons) HeadAndTd() (hash common.Hash, td *big.Int) {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 
-	return blockInfo{Hash: p.headInfo.Hash, Number: p.headInfo.Number, Td: p.headInfo.Td}
+	return p.headInfo.Hash, new(big.Int).Set(p.headInfo.Td)
 }
 
-// Td retrieves the current total difficulty of a peer.
-func (p *peer) Td() *big.Int {
-	p.lock.RLock()
-	defer p.lock.RUnlock()
+// sendReceiveHandshake exchanges handshake packet with remote peer and returns any error
+// if failed to send or receive packet.
+func (p *peerCommons) sendReceiveHandshake(sendList keyValueList) (keyValueList, error) {
+	var (
+		errc     = make(chan error, 2)
+		recvList keyValueList
+	)
+	// Send out own handshake in a new thread
+	go func() {
+		errc <- p2p.Send(p.rw, StatusMsg, sendList)
+	}()
+	go func() {
+		// In the mean time retrieve the remote status message
+		msg, err := p.rw.ReadMsg()
+		if err != nil {
+			errc <- err
+			return
+		}
+		if msg.Code != StatusMsg {
+			errc <- errResp(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
+			return
+		}
+		if msg.Size > ProtocolMaxMsgSize {
+			errc <- errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
+			return
+		}
+		// Decode the handshake
+		if err := msg.Decode(&recvList); err != nil {
+			errc <- errResp(ErrDecode, "msg %v: %v", msg, err)
+			return
+		}
+		errc <- nil
+	}()
+	timeout := time.NewTimer(handshakeTimeout)
+	defer timeout.Stop()
+	for i := 0; i < 2; i++ {
+		select {
+		case err := <-errc:
+			if err != nil {
+				return nil, err
+			}
+		case <-timeout.C:
+			return nil, p2p.DiscReadTimeout
+		}
+	}
+	return recvList, nil
+}
 
-	return new(big.Int).Set(p.headInfo.Td)
+// handshake executes the les protocol handshake, negotiating version number,
+// network IDs, difficulties, head and genesis blocks. Besides the basic handshake
+// fields, server and client can exchange and resolve some specified fields through
+// two callback functions.
+func (p *peerCommons) handshake(td *big.Int, head common.Hash, headNum uint64, genesis common.Hash, sendCallback func(*keyValueList), recvCallback func(keyValueMap) error) error {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	var send keyValueList
+
+	// Add some basic handshake fields
+	send = send.add("protocolVersion", uint64(p.version))
+	send = send.add("networkId", p.network)
+	send = send.add("headTd", td)
+	send = send.add("headHash", head)
+	send = send.add("headNum", headNum)
+	send = send.add("genesisHash", genesis)
+
+	// Add client-specified or server-specified fields
+	if sendCallback != nil {
+		sendCallback(&send)
+	}
+	// Exchange the handshake packet and resolve the received one.
+	recvList, err := p.sendReceiveHandshake(send)
+	if err != nil {
+		return err
+	}
+	recv, size := recvList.decode()
+	if size > allowedUpdateBytes {
+		return errResp(ErrRequestRejected, "")
+	}
+	var rGenesis, rHash common.Hash
+	var rVersion, rNetwork, rNum uint64
+	var rTd *big.Int
+	if err := recv.get("protocolVersion", &rVersion); err != nil {
+		return err
+	}
+	if err := recv.get("networkId", &rNetwork); err != nil {
+		return err
+	}
+	if err := recv.get("headTd", &rTd); err != nil {
+		return err
+	}
+	if err := recv.get("headHash", &rHash); err != nil {
+		return err
+	}
+	if err := recv.get("headNum", &rNum); err != nil {
+		return err
+	}
+	if err := recv.get("genesisHash", &rGenesis); err != nil {
+		return err
+	}
+	if rGenesis != genesis {
+		return errResp(ErrGenesisBlockMismatch, "%x (!= %x)", rGenesis[:8], genesis[:8])
+	}
+	if rNetwork != p.network {
+		return errResp(ErrNetworkIdMismatch, "%d (!= %d)", rNetwork, p.network)
+	}
+	if int(rVersion) != p.version {
+		return errResp(ErrProtocolVersionMismatch, "%d (!= %d)", rVersion, p.version)
+	}
+	p.headInfo = blockInfo{Hash: rHash, Number: rNum, Td: rTd}
+	if recvCallback != nil {
+		return recvCallback(recv)
+	}
+	return nil
 }
 
-// waitBefore implements distPeer interface
-func (p *peer) waitBefore(maxCost uint64) (time.Duration, float64) {
-	return p.fcServer.CanSend(maxCost)
+// close closes the channel and notifies all background routines to exit.
+func (p *peerCommons) close() {
+	close(p.closeCh)
+	p.sendQueue.quit()
 }
 
-// updateCapacity updates the request serving capacity assigned to a given client
-// and also sends an announcement about the updated flow control parameters
-func (p *peer) updateCapacity(cap uint64) {
-	p.responseLock.Lock()
-	defer p.responseLock.Unlock()
+// serverPeer represents each node to which the client is connected.
+// The node here refers to the les server.
+type serverPeer struct {
+	peerCommons
 
-	p.fcParams = flowcontrol.ServerParams{MinRecharge: cap, BufLimit: cap * bufLimitRatio}
-	p.fcClient.UpdateParams(p.fcParams)
-	var kvList keyValueList
-	kvList = kvList.add("flowControl/MRR", cap)
-	kvList = kvList.add("flowControl/BL", cap*bufLimitRatio)
-	p.queueSend(func() { p.SendAnnounce(announceData{Update: kvList}) })
+	// Status fields
+	trusted                 bool   // The flag whether the server is selected as trusted server.
+	onlyAnnounce            bool   // The flag whether the server sends announcement only.
+	chainSince, chainRecent uint64 // The range of chain server peer can serve.
+	stateSince, stateRecent uint64 // The range of state server peer can serve.
+
+	// Advertised checkpoint fields
+	checkpointNumber uint64                   // The block height which the checkpoint is registered.
+	checkpoint       params.TrustedCheckpoint // The advertised checkpoint sent by server.
+
+	poolEntry *poolEntry              // Statistic for server peer.
+	fcServer  *flowcontrol.ServerNode // Client side mirror token bucket.
+
+	// Statistics
+	errCount    int // Counter the invalid responses server has replied
+	updateCount uint64
+	updateTime  mclock.AbsTime
+
+	// Callbacks
+	hasBlock func(common.Hash, uint64, bool) bool // Used to determine whether the server has the specified block.
 }
 
-func (p *peer) responseID() uint64 {
-	p.responseCount += 1
-	return p.responseCount
+func newServerPeer(version int, network uint64, trusted bool, p *p2p.Peer, rw p2p.MsgReadWriter) *serverPeer {
+	return &serverPeer{
+		peerCommons: peerCommons{
+			Peer:      p,
+			rw:        rw,
+			id:        peerIdToString(p.ID()),
+			version:   version,
+			network:   network,
+			sendQueue: newExecQueue(100),
+			closeCh:   make(chan struct{}),
+		},
+		trusted: trusted,
+	}
 }
 
-func sendRequest(w p2p.MsgWriter, msgcode, reqID, cost uint64, data interface{}) error {
+// rejectUpdate returns true if a parameter update has to be rejected because
+// the size and/or rate of updates exceed the capacity limitation
+func (p *serverPeer) rejectUpdate(size uint64) bool {
+	now := mclock.Now()
+	if p.updateCount == 0 {
+		p.updateTime = now
+	} else {
+		dt := now - p.updateTime
+		p.updateTime = now
+
+		r := uint64(dt / mclock.AbsTime(allowedUpdateRate))
+		if p.updateCount > r {
+			p.updateCount -= r
+		} else {
+			p.updateCount = 0
+		}
+	}
+	p.updateCount += size
+	return p.updateCount > allowedUpdateBytes
+}
+
+// freeze processes Stop messages from the given server and set the status as
+// frozen.
+func (p *serverPeer) freeze() {
+	if atomic.CompareAndSwapUint32(&p.frozen, 0, 1) {
+		p.sendQueue.clear()
+	}
+}
+
+// unfreeze processes Resume messages from the given server and set the status
+// as unfrozen.
+func (p *serverPeer) unfreeze() {
+	atomic.StoreUint32(&p.frozen, 0)
+}
+
+// sendRequest send a request to the server based on the given message type
+// and content.
+func sendRequest(w p2p.MsgWriter, msgcode, reqID uint64, data interface{}) error {
 	type req struct {
 		ReqID uint64
 		Data  interface{}
@@ -304,30 +426,72 @@ func sendRequest(w p2p.MsgWriter, msgcode, reqID, cost uint64, data interface{})
 	return p2p.Send(w, msgcode, req{reqID, data})
 }
 
-// reply struct represents a reply with the actual data already RLP encoded and
-// only the bv (buffer value) missing. This allows the serving mechanism to
-// calculate the bv value which depends on the data size before sending the reply.
-type reply struct {
-	w              p2p.MsgWriter
-	msgcode, reqID uint64
-	data           rlp.RawValue
+// requestHeadersByHash fetches a batch of blocks' headers corresponding to the
+// specified header query, based on the hash of an origin block.
+func (p *serverPeer) requestHeadersByHash(reqID uint64, origin common.Hash, amount int, skip int, reverse bool) error {
+	p.Log().Debug("Fetching batch of headers", "count", amount, "fromhash", origin, "skip", skip, "reverse", reverse)
+	return sendRequest(p.rw, GetBlockHeadersMsg, reqID, &getBlockHeadersData{Origin: hashOrNumber{Hash: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
 }
 
-// send sends the reply with the calculated buffer value
-func (r *reply) send(bv uint64) error {
-	type resp struct {
-		ReqID, BV uint64
-		Data      rlp.RawValue
-	}
-	return p2p.Send(r.w, r.msgcode, resp{r.reqID, bv, r.data})
+// requestHeadersByNumber fetches a batch of blocks' headers corresponding to the
+// specified header query, based on the number of an origin block.
+func (p *serverPeer) requestHeadersByNumber(reqID, origin uint64, amount int, skip int, reverse bool) error {
+	p.Log().Debug("Fetching batch of headers", "count", amount, "fromnum", origin, "skip", skip, "reverse", reverse)
+	return sendRequest(p.rw, GetBlockHeadersMsg, reqID, &getBlockHeadersData{Origin: hashOrNumber{Number: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
 }
 
-// size returns the RLP encoded size of the message data
-func (r *reply) size() uint32 {
-	return uint32(len(r.data))
+// requestBodies fetches a batch of blocks' bodies corresponding to the hashes
+// specified.
+func (p *serverPeer) requestBodies(reqID uint64, hashes []common.Hash) error {
+	p.Log().Debug("Fetching batch of block bodies", "count", len(hashes))
+	return sendRequest(p.rw, GetBlockBodiesMsg, reqID, hashes)
+}
+
+// requestCode fetches a batch of arbitrary data from a node's known state
+// data, corresponding to the specified hashes.
+func (p *serverPeer) requestCode(reqID uint64, reqs []CodeReq) error {
+	p.Log().Debug("Fetching batch of codes", "count", len(reqs))
+	return sendRequest(p.rw, GetCodeMsg, reqID, reqs)
+}
+
+// requestReceipts fetches a batch of transaction receipts from a remote node.
+func (p *serverPeer) requestReceipts(reqID uint64, hashes []common.Hash) error {
+	p.Log().Debug("Fetching batch of receipts", "count", len(hashes))
+	return sendRequest(p.rw, GetReceiptsMsg, reqID, hashes)
+}
+
+// requestProofs fetches a batch of merkle proofs from a remote node.
+func (p *serverPeer) requestProofs(reqID uint64, reqs []ProofReq) error {
+	p.Log().Debug("Fetching batch of proofs", "count", len(reqs))
+	return sendRequest(p.rw, GetProofsV2Msg, reqID, reqs)
+}
+
+// requestHelperTrieProofs fetches a batch of HelperTrie merkle proofs from a remote node.
+func (p *serverPeer) requestHelperTrieProofs(reqID uint64, reqs []HelperTrieReq) error {
+	p.Log().Debug("Fetching batch of HelperTrie proofs", "count", len(reqs))
+	return sendRequest(p.rw, GetHelperTrieProofsMsg, reqID, reqs)
+}
+
+// requestTxStatus fetches a batch of transaction status records from a remote node.
+func (p *serverPeer) requestTxStatus(reqID uint64, txHashes []common.Hash) error {
+	p.Log().Debug("Requesting transaction status", "count", len(txHashes))
+	return sendRequest(p.rw, GetTxStatusMsg, reqID, txHashes)
+}
+
+// SendTxStatus creates a reply with a batch of transactions to be added to the remote transaction pool.
+func (p *serverPeer) sendTxs(reqID uint64, txs rlp.RawValue) error {
+	p.Log().Debug("Sending batch of transactions", "size", len(txs))
+	return sendRequest(p.rw, SendTxV2Msg, reqID, txs)
+}
+
+// waitBefore implements distPeer interface
+func (p *serverPeer) waitBefore(maxCost uint64) (time.Duration, float64) {
+	return p.fcServer.CanSend(maxCost)
 }
 
-func (p *peer) GetRequestCost(msgcode uint64, amount int) uint64 {
+// getRequestCost returns an estimated request cost according to the flow control
+// rules negotiated between the server and the client.
+func (p *serverPeer) getRequestCost(msgcode uint64, amount int) uint64 {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 
@@ -342,7 +506,9 @@ func (p *peer) GetRequestCost(msgcode uint64, amount int) uint64 {
 	return cost
 }
 
-func (p *peer) GetTxRelayCost(amount, size int) uint64 {
+// getTxRelayCost returns an estimated relay cost according to the flow control
+// rules negotiated between the server and the client.
+func (p *serverPeer) getTxRelayCost(amount, size int) uint64 {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 
@@ -355,7 +521,6 @@ func (p *peer) GetTxRelayCost(amount, size int) uint64 {
 	if sizeCost > cost {
 		cost = sizeCost
 	}
-
 	if cost > p.fcParams.BufLimit {
 		cost = p.fcParams.BufLimit
 	}
@@ -363,12 +528,12 @@ func (p *peer) GetTxRelayCost(amount, size int) uint64 {
 }
 
 // HasBlock checks if the peer has a given block
-func (p *peer) HasBlock(hash common.Hash, number uint64, hasState bool) bool {
-	var head, since, recent uint64
+func (p *serverPeer) HasBlock(hash common.Hash, number uint64, hasState bool) bool {
 	p.lock.RLock()
-	if p.headInfo != nil {
-		head = p.headInfo.Number
-	}
+	defer p.lock.RUnlock()
+
+	head := p.headInfo.Number
+	var since, recent uint64
 	if hasState {
 		since = p.stateSince
 		recent = p.stateRecent
@@ -377,220 +542,313 @@ func (p *peer) HasBlock(hash common.Hash, number uint64, hasState bool) bool {
 		recent = p.chainRecent
 	}
 	hasBlock := p.hasBlock
-	p.lock.RUnlock()
 
 	return head >= number && number >= since && (recent == 0 || number+recent+4 > head) && hasBlock != nil && hasBlock(hash, number, hasState)
 }
 
-// SendAnnounce announces the availability of a number of blocks through
-// a hash notification.
-func (p *peer) SendAnnounce(request announceData) error {
-	return p2p.Send(p.rw, AnnounceMsg, request)
+// updateFlowControl updates the flow control parameters belonging to the server
+// node if the announced key/value set contains relevant fields
+func (p *serverPeer) updateFlowControl(update keyValueMap) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	// If any of the flow control params is nil, refuse to update.
+	var params flowcontrol.ServerParams
+	if update.get("flowControl/BL", &params.BufLimit) == nil && update.get("flowControl/MRR", &params.MinRecharge) == nil {
+		// todo can light client set a minimal acceptable flow control params?
+		p.fcParams = params
+		p.fcServer.UpdateParams(params)
+	}
+	var MRC RequestCostList
+	if update.get("flowControl/MRC", &MRC) == nil {
+		costUpdate := MRC.decode(ProtocolLengths[uint(p.version)])
+		for code, cost := range costUpdate {
+			p.fcCosts[code] = cost
+		}
+	}
+}
+
+// Handshake executes the les protocol handshake, negotiating version number,
+// network IDs, difficulties, head and genesis blocks.
+func (p *serverPeer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis common.Hash, server *LesServer) error {
+	return p.handshake(td, head, headNum, genesis, func(lists *keyValueList) {
+		// Add some client-specific handshake fields
+		//
+		// Enable signed announcement randomly even the server is not trusted.
+		p.announceType = announceTypeSimple
+		if p.trusted {
+			p.announceType = announceTypeSigned
+		}
+		*lists = (*lists).add("announceType", p.announceType)
+	}, func(recv keyValueMap) error {
+		if recv.get("serveChainSince", &p.chainSince) != nil {
+			p.onlyAnnounce = true
+		}
+		if recv.get("serveRecentChain", &p.chainRecent) != nil {
+			p.chainRecent = 0
+		}
+		if recv.get("serveStateSince", &p.stateSince) != nil {
+			p.onlyAnnounce = true
+		}
+		if recv.get("serveRecentState", &p.stateRecent) != nil {
+			p.stateRecent = 0
+		}
+		if recv.get("txRelay", nil) != nil {
+			p.onlyAnnounce = true
+		}
+		if p.onlyAnnounce && !p.trusted {
+			return errResp(ErrUselessPeer, "peer cannot serve requests")
+		}
+		// Parse flow control handshake packet.
+		var sParams flowcontrol.ServerParams
+		if err := recv.get("flowControl/BL", &sParams.BufLimit); err != nil {
+			return err
+		}
+		if err := recv.get("flowControl/MRR", &sParams.MinRecharge); err != nil {
+			return err
+		}
+		var MRC RequestCostList
+		if err := recv.get("flowControl/MRC", &MRC); err != nil {
+			return err
+		}
+		p.fcParams = sParams
+		p.fcServer = flowcontrol.NewServerNode(sParams, &mclock.System{})
+		p.fcCosts = MRC.decode(ProtocolLengths[uint(p.version)])
+
+		recv.get("checkpoint/value", &p.checkpoint)
+		recv.get("checkpoint/registerHeight", &p.checkpointNumber)
+
+		if !p.onlyAnnounce {
+			for msgCode := range reqAvgTimeCost {
+				if p.fcCosts[msgCode] == nil {
+					return errResp(ErrUselessPeer, "peer does not support message %d", msgCode)
+				}
+			}
+		}
+		return nil
+	})
+}
+
+// clientPeer represents each node to which the les server is connected.
+// The node here refers to the light client.
+type clientPeer struct {
+	peerCommons
+
+	// responseLock ensures that responses are queued in the same order as
+	// RequestProcessed is called
+	responseLock   sync.Mutex
+	server         bool
+	invalidCount   uint32 // Counter the invalid request the client peer has made.
+	responseCount  uint64 // Counter to generate an unique id for request processing.
+	errCh          chan error
+	fcClient       *flowcontrol.ClientNode // Server side mirror token bucket.
+	balanceTracker *balanceTracker         // set by clientPool.connect, used and removed by serverHandler
+}
+
+func newClientPeer(version int, network uint64, p *p2p.Peer, rw p2p.MsgReadWriter) *clientPeer {
+	return &clientPeer{
+		peerCommons: peerCommons{
+			Peer:      p,
+			rw:        rw,
+			id:        peerIdToString(p.ID()),
+			version:   version,
+			network:   network,
+			sendQueue: newExecQueue(100),
+			closeCh:   make(chan struct{}),
+		},
+		errCh: make(chan error, 1),
+	}
+}
+
+// freeClientId returns a string identifier for the peer. Multiple peers with
+// the same identifier can not be connected in free mode simultaneously.
+func (p *clientPeer) freeClientId() string {
+	if addr, ok := p.RemoteAddr().(*net.TCPAddr); ok {
+		if addr.IP.IsLoopback() {
+			// using peer id instead of loopback ip address allows multiple free
+			// connections from local machine to own server
+			return p.id
+		} else {
+			return addr.IP.String()
+		}
+	}
+	return p.id
 }
 
-// SendStop notifies the client about being in frozen state
-func (p *peer) SendStop() error {
+// sendStop notifies the client about being in frozen state
+func (p *clientPeer) sendStop() error {
 	return p2p.Send(p.rw, StopMsg, struct{}{})
 }
 
-// SendResume notifies the client about getting out of frozen state
-func (p *peer) SendResume(bv uint64) error {
+// sendResume notifies the client about getting out of frozen state
+func (p *clientPeer) sendResume(bv uint64) error {
 	return p2p.Send(p.rw, ResumeMsg, bv)
 }
 
-// ReplyBlockHeaders creates a reply with a batch of block headers
-func (p *peer) ReplyBlockHeaders(reqID uint64, headers []*types.Header) *reply {
+// freeze temporarily puts the client in a frozen state which means all unprocessed
+// and subsequent requests are dropped. Unfreezing happens automatically after a short
+// time if the client's buffer value is at least in the slightly positive region.
+// The client is also notified about being frozen/unfrozen with a Stop/Resume message.
+func (p *clientPeer) freeze() {
+	if p.version < lpv3 {
+		// if Stop/Resume is not supported then just drop the peer after setting
+		// its frozen status permanently
+		atomic.StoreUint32(&p.frozen, 1)
+		p.Peer.Disconnect(p2p.DiscUselessPeer)
+		return
+	}
+	if atomic.SwapUint32(&p.frozen, 1) == 0 {
+		go func() {
+			p.sendStop()
+			time.Sleep(freezeTimeBase + time.Duration(rand.Int63n(int64(freezeTimeRandom))))
+			for {
+				bufValue, bufLimit := p.fcClient.BufferStatus()
+				if bufLimit == 0 {
+					return
+				}
+				if bufValue <= bufLimit/8 {
+					time.Sleep(freezeCheckPeriod)
+					continue
+				}
+				atomic.StoreUint32(&p.frozen, 0)
+				p.sendResume(bufValue)
+				return
+			}
+		}()
+	}
+}
+
+// reply struct represents a reply with the actual data already RLP encoded and
+// only the bv (buffer value) missing. This allows the serving mechanism to
+// calculate the bv value which depends on the data size before sending the reply.
+type reply struct {
+	w              p2p.MsgWriter
+	msgcode, reqID uint64
+	data           rlp.RawValue
+}
+
+// send sends the reply with the calculated buffer value
+func (r *reply) send(bv uint64) error {
+	type resp struct {
+		ReqID, BV uint64
+		Data      rlp.RawValue
+	}
+	return p2p.Send(r.w, r.msgcode, resp{r.reqID, bv, r.data})
+}
+
+// size returns the RLP encoded size of the message data
+func (r *reply) size() uint32 {
+	return uint32(len(r.data))
+}
+
+// replyBlockHeaders creates a reply with a batch of block headers
+func (p *clientPeer) replyBlockHeaders(reqID uint64, headers []*types.Header) *reply {
 	data, _ := rlp.EncodeToBytes(headers)
 	return &reply{p.rw, BlockHeadersMsg, reqID, data}
 }
 
-// ReplyBlockBodiesRLP creates a reply with a batch of block contents from
+// replyBlockBodiesRLP creates a reply with a batch of block contents from
 // an already RLP encoded format.
-func (p *peer) ReplyBlockBodiesRLP(reqID uint64, bodies []rlp.RawValue) *reply {
+func (p *clientPeer) replyBlockBodiesRLP(reqID uint64, bodies []rlp.RawValue) *reply {
 	data, _ := rlp.EncodeToBytes(bodies)
 	return &reply{p.rw, BlockBodiesMsg, reqID, data}
 }
 
-// ReplyCode creates a reply with a batch of arbitrary internal data, corresponding to the
+// replyCode creates a reply with a batch of arbitrary internal data, corresponding to the
 // hashes requested.
-func (p *peer) ReplyCode(reqID uint64, codes [][]byte) *reply {
+func (p *clientPeer) replyCode(reqID uint64, codes [][]byte) *reply {
 	data, _ := rlp.EncodeToBytes(codes)
 	return &reply{p.rw, CodeMsg, reqID, data}
 }
 
-// ReplyReceiptsRLP creates a reply with a batch of transaction receipts, corresponding to the
+// replyReceiptsRLP creates a reply with a batch of transaction receipts, corresponding to the
 // ones requested from an already RLP encoded format.
-func (p *peer) ReplyReceiptsRLP(reqID uint64, receipts []rlp.RawValue) *reply {
+func (p *clientPeer) replyReceiptsRLP(reqID uint64, receipts []rlp.RawValue) *reply {
 	data, _ := rlp.EncodeToBytes(receipts)
 	return &reply{p.rw, ReceiptsMsg, reqID, data}
 }
 
-// ReplyProofsV2 creates a reply with a batch of merkle proofs, corresponding to the ones requested.
-func (p *peer) ReplyProofsV2(reqID uint64, proofs light.NodeList) *reply {
+// replyProofsV2 creates a reply with a batch of merkle proofs, corresponding to the ones requested.
+func (p *clientPeer) replyProofsV2(reqID uint64, proofs light.NodeList) *reply {
 	data, _ := rlp.EncodeToBytes(proofs)
 	return &reply{p.rw, ProofsV2Msg, reqID, data}
 }
 
-// ReplyHelperTrieProofs creates a reply with a batch of HelperTrie proofs, corresponding to the ones requested.
-func (p *peer) ReplyHelperTrieProofs(reqID uint64, resp HelperTrieResps) *reply {
+// replyHelperTrieProofs creates a reply with a batch of HelperTrie proofs, corresponding to the ones requested.
+func (p *clientPeer) replyHelperTrieProofs(reqID uint64, resp HelperTrieResps) *reply {
 	data, _ := rlp.EncodeToBytes(resp)
 	return &reply{p.rw, HelperTrieProofsMsg, reqID, data}
 }
 
-// ReplyTxStatus creates a reply with a batch of transaction status records, corresponding to the ones requested.
-func (p *peer) ReplyTxStatus(reqID uint64, stats []light.TxStatus) *reply {
+// replyTxStatus creates a reply with a batch of transaction status records, corresponding to the ones requested.
+func (p *clientPeer) replyTxStatus(reqID uint64, stats []light.TxStatus) *reply {
 	data, _ := rlp.EncodeToBytes(stats)
 	return &reply{p.rw, TxStatusMsg, reqID, data}
 }
 
-// RequestHeadersByHash fetches a batch of blocks' headers corresponding to the
-// specified header query, based on the hash of an origin block.
-func (p *peer) RequestHeadersByHash(reqID, cost uint64, origin common.Hash, amount int, skip int, reverse bool) error {
-	p.Log().Debug("Fetching batch of headers", "count", amount, "fromhash", origin, "skip", skip, "reverse", reverse)
-	return sendRequest(p.rw, GetBlockHeadersMsg, reqID, cost, &getBlockHeadersData{Origin: hashOrNumber{Hash: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
-}
-
-// RequestHeadersByNumber fetches a batch of blocks' headers corresponding to the
-// specified header query, based on the number of an origin block.
-func (p *peer) RequestHeadersByNumber(reqID, cost, origin uint64, amount int, skip int, reverse bool) error {
-	p.Log().Debug("Fetching batch of headers", "count", amount, "fromnum", origin, "skip", skip, "reverse", reverse)
-	return sendRequest(p.rw, GetBlockHeadersMsg, reqID, cost, &getBlockHeadersData{Origin: hashOrNumber{Number: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
-}
-
-// RequestBodies fetches a batch of blocks' bodies corresponding to the hashes
-// specified.
-func (p *peer) RequestBodies(reqID, cost uint64, hashes []common.Hash) error {
-	p.Log().Debug("Fetching batch of block bodies", "count", len(hashes))
-	return sendRequest(p.rw, GetBlockBodiesMsg, reqID, cost, hashes)
-}
-
-// RequestCode fetches a batch of arbitrary data from a node's known state
-// data, corresponding to the specified hashes.
-func (p *peer) RequestCode(reqID, cost uint64, reqs []CodeReq) error {
-	p.Log().Debug("Fetching batch of codes", "count", len(reqs))
-	return sendRequest(p.rw, GetCodeMsg, reqID, cost, reqs)
-}
-
-// RequestReceipts fetches a batch of transaction receipts from a remote node.
-func (p *peer) RequestReceipts(reqID, cost uint64, hashes []common.Hash) error {
-	p.Log().Debug("Fetching batch of receipts", "count", len(hashes))
-	return sendRequest(p.rw, GetReceiptsMsg, reqID, cost, hashes)
-}
-
-// RequestProofs fetches a batch of merkle proofs from a remote node.
-func (p *peer) RequestProofs(reqID, cost uint64, reqs []ProofReq) error {
-	p.Log().Debug("Fetching batch of proofs", "count", len(reqs))
-	return sendRequest(p.rw, GetProofsV2Msg, reqID, cost, reqs)
-}
-
-// RequestHelperTrieProofs fetches a batch of HelperTrie merkle proofs from a remote node.
-func (p *peer) RequestHelperTrieProofs(reqID, cost uint64, reqs []HelperTrieReq) error {
-	p.Log().Debug("Fetching batch of HelperTrie proofs", "count", len(reqs))
-	return sendRequest(p.rw, GetHelperTrieProofsMsg, reqID, cost, reqs)
-}
-
-// RequestTxStatus fetches a batch of transaction status records from a remote node.
-func (p *peer) RequestTxStatus(reqID, cost uint64, txHashes []common.Hash) error {
-	p.Log().Debug("Requesting transaction status", "count", len(txHashes))
-	return sendRequest(p.rw, GetTxStatusMsg, reqID, cost, txHashes)
-}
-
-// SendTxStatus creates a reply with a batch of transactions to be added to the remote transaction pool.
-func (p *peer) SendTxs(reqID, cost uint64, txs rlp.RawValue) error {
-	p.Log().Debug("Sending batch of transactions", "size", len(txs))
-	return sendRequest(p.rw, SendTxV2Msg, reqID, cost, txs)
-}
-
-type keyValueEntry struct {
-	Key   string
-	Value rlp.RawValue
-}
-type keyValueList []keyValueEntry
-type keyValueMap map[string]rlp.RawValue
-
-func (l keyValueList) add(key string, val interface{}) keyValueList {
-	var entry keyValueEntry
-	entry.Key = key
-	if val == nil {
-		val = uint64(0)
-	}
-	enc, err := rlp.EncodeToBytes(val)
-	if err == nil {
-		entry.Value = enc
-	}
-	return append(l, entry)
-}
-
-func (l keyValueList) decode() (keyValueMap, uint64) {
-	m := make(keyValueMap)
-	var size uint64
-	for _, entry := range l {
-		m[entry.Key] = entry.Value
-		size += uint64(len(entry.Key)) + uint64(len(entry.Value)) + 8
-	}
-	return m, size
-}
-
-func (m keyValueMap) get(key string, val interface{}) error {
-	enc, ok := m[key]
-	if !ok {
-		return errResp(ErrMissingKey, "%s", key)
-	}
-	if val == nil {
-		return nil
-	}
-	return rlp.DecodeBytes(enc, val)
+// sendAnnounce announces the availability of a number of blocks through
+// a hash notification.
+func (p *clientPeer) sendAnnounce(request announceData) error {
+	return p2p.Send(p.rw, AnnounceMsg, request)
 }
 
-func (p *peer) sendReceiveHandshake(sendList keyValueList) (keyValueList, error) {
-	// Send out own handshake in a new thread
-	errc := make(chan error, 1)
-	go func() {
-		errc <- p2p.Send(p.rw, StatusMsg, sendList)
-	}()
-	// In the mean time retrieve the remote status message
-	msg, err := p.rw.ReadMsg()
-	if err != nil {
-		return nil, err
-	}
-	if msg.Code != StatusMsg {
-		return nil, errResp(ErrNoStatusMsg, "first msg has code %x (!= %x)", msg.Code, StatusMsg)
-	}
-	if msg.Size > ProtocolMaxMsgSize {
-		return nil, errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
-	}
-	// Decode the handshake
-	var recvList keyValueList
-	if err := msg.Decode(&recvList); err != nil {
-		return nil, errResp(ErrDecode, "msg %v: %v", msg, err)
+// updateCapacity updates the request serving capacity assigned to a given client
+// and also sends an announcement about the updated flow control parameters
+func (p *clientPeer) updateCapacity(cap uint64) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.fcParams = flowcontrol.ServerParams{MinRecharge: cap, BufLimit: cap * bufLimitRatio}
+	p.fcClient.UpdateParams(p.fcParams)
+	var kvList keyValueList
+	kvList = kvList.add("flowControl/MRR", cap)
+	kvList = kvList.add("flowControl/BL", cap*bufLimitRatio)
+	p.mustQueueSend(func() { p.sendAnnounce(announceData{Update: kvList}) })
+}
+
+// freezeClient temporarily puts the client in a frozen state which means all
+// unprocessed and subsequent requests are dropped. Unfreezing happens automatically
+// after a short time if the client's buffer value is at least in the slightly positive
+// region. The client is also notified about being frozen/unfrozen with a Stop/Resume
+// message.
+func (p *clientPeer) freezeClient() {
+	if p.version < lpv3 {
+		// if Stop/Resume is not supported then just drop the peer after setting
+		// its frozen status permanently
+		atomic.StoreUint32(&p.frozen, 1)
+		p.Peer.Disconnect(p2p.DiscUselessPeer)
+		return
 	}
-	if err := <-errc; err != nil {
-		return nil, err
+	if atomic.SwapUint32(&p.frozen, 1) == 0 {
+		go func() {
+			p.sendStop()
+			time.Sleep(freezeTimeBase + time.Duration(rand.Int63n(int64(freezeTimeRandom))))
+			for {
+				bufValue, bufLimit := p.fcClient.BufferStatus()
+				if bufLimit == 0 {
+					return
+				}
+				if bufValue <= bufLimit/8 {
+					time.Sleep(freezeCheckPeriod)
+				} else {
+					atomic.StoreUint32(&p.frozen, 0)
+					p.sendResume(bufValue)
+					break
+				}
+			}
+		}()
 	}
-	return recvList, nil
 }
 
 // Handshake executes the les protocol handshake, negotiating version number,
 // network IDs, difficulties, head and genesis blocks.
-func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis common.Hash, server *LesServer) error {
-	p.lock.Lock()
-	defer p.lock.Unlock()
-
-	var send keyValueList
-
-	// Add some basic handshake fields
-	send = send.add("protocolVersion", uint64(p.version))
-	send = send.add("networkId", p.network)
-	send = send.add("headTd", td)
-	send = send.add("headHash", head)
-	send = send.add("headNum", headNum)
-	send = send.add("genesisHash", genesis)
-	if server != nil {
+func (p *clientPeer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis common.Hash, server *LesServer) error {
+	return p.handshake(td, head, headNum, genesis, func(lists *keyValueList) {
 		// Add some information which services server can offer.
 		if !server.config.UltraLightOnlyAnnounce {
-			send = send.add("serveHeaders", nil)
-			send = send.add("serveChainSince", uint64(0))
-			send = send.add("serveStateSince", uint64(0))
+			*lists = (*lists).add("serveHeaders", nil)
+			*lists = (*lists).add("serveChainSince", uint64(0))
+			*lists = (*lists).add("serveStateSince", uint64(0))
 
 			// If local ethereum node is running in archive mode, advertise ourselves we have
 			// all version state data. Otherwise only recent state is available.
@@ -598,11 +856,11 @@ func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis
 			if server.archiveMode {
 				stateRecent = 0
 			}
-			send = send.add("serveRecentState", stateRecent)
-			send = send.add("txRelay", nil)
+			*lists = (*lists).add("serveRecentState", stateRecent)
+			*lists = (*lists).add("txRelay", nil)
 		}
-		send = send.add("flowControl/BL", server.defParams.BufLimit)
-		send = send.add("flowControl/MRR", server.defParams.MinRecharge)
+		*lists = (*lists).add("flowControl/BL", server.defParams.BufLimit)
+		*lists = (*lists).add("flowControl/MRR", server.defParams.MinRecharge)
 
 		var costList RequestCostList
 		if server.costTracker.testCostList != nil {
@@ -610,7 +868,7 @@ func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis
 		} else {
 			costList = server.costTracker.makeCostList(server.costTracker.globalFactor())
 		}
-		send = send.add("flowControl/MRC", costList)
+		*lists = (*lists).add("flowControl/MRC", costList)
 		p.fcCosts = costList.decode(ProtocolLengths[uint(p.version)])
 		p.fcParams = server.defParams
 
@@ -619,62 +877,11 @@ func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis
 		if server.oracle != nil && server.oracle.IsRunning() {
 			cp, height := server.oracle.StableCheckpoint()
 			if cp != nil {
-				send = send.add("checkpoint/value", cp)
-				send = send.add("checkpoint/registerHeight", height)
+				*lists = (*lists).add("checkpoint/value", cp)
+				*lists = (*lists).add("checkpoint/registerHeight", height)
 			}
 		}
-	} else {
-		// Add some client-specific handshake fields
-		p.announceType = announceTypeSimple
-		if p.trusted {
-			p.announceType = announceTypeSigned
-		}
-		send = send.add("announceType", p.announceType)
-	}
-
-	recvList, err := p.sendReceiveHandshake(send)
-	if err != nil {
-		return err
-	}
-	recv, size := recvList.decode()
-	if p.rejectUpdate(size) {
-		return errResp(ErrRequestRejected, "")
-	}
-
-	var rGenesis, rHash common.Hash
-	var rVersion, rNetwork, rNum uint64
-	var rTd *big.Int
-
-	if err := recv.get("protocolVersion", &rVersion); err != nil {
-		return err
-	}
-	if err := recv.get("networkId", &rNetwork); err != nil {
-		return err
-	}
-	if err := recv.get("headTd", &rTd); err != nil {
-		return err
-	}
-	if err := recv.get("headHash", &rHash); err != nil {
-		return err
-	}
-	if err := recv.get("headNum", &rNum); err != nil {
-		return err
-	}
-	if err := recv.get("genesisHash", &rGenesis); err != nil {
-		return err
-	}
-
-	if rGenesis != genesis {
-		return errResp(ErrGenesisBlockMismatch, "%x (!= %x)", rGenesis[:8], genesis[:8])
-	}
-	if rNetwork != p.network {
-		return errResp(ErrNetworkIdMismatch, "%d (!= %d)", rNetwork, p.network)
-	}
-	if int(rVersion) != p.version {
-		return errResp(ErrProtocolVersionMismatch, "%d (!= %d)", rVersion, p.version)
-	}
-
-	if server != nil {
+	}, func(recv keyValueMap) error {
 		p.server = recv.get("flowControl/MRR", nil) == nil
 		if p.server {
 			p.announceType = announceTypeNone // connected to another server, send no messages
@@ -685,237 +892,298 @@ func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis
 			}
 			p.fcClient = flowcontrol.NewClientNode(server.fcManager, server.defParams)
 		}
-	} else {
-		if recv.get("serveChainSince", &p.chainSince) != nil {
-			p.onlyAnnounce = true
-		}
-		if recv.get("serveRecentChain", &p.chainRecent) != nil {
-			p.chainRecent = 0
-		}
-		if recv.get("serveStateSince", &p.stateSince) != nil {
-			p.onlyAnnounce = true
-		}
-		if recv.get("serveRecentState", &p.stateRecent) != nil {
-			p.stateRecent = 0
-		}
-		if recv.get("txRelay", nil) != nil {
-			p.onlyAnnounce = true
-		}
+		return nil
+	})
+}
 
-		if p.onlyAnnounce && !p.trusted {
-			return errResp(ErrUselessPeer, "peer cannot serve requests")
-		}
+// serverPeerSubscriber is an interface to notify services about added or
+// removed server peers
+type serverPeerSubscriber interface {
+	registerPeer(*serverPeer)
+	unregisterPeer(*serverPeer)
+}
 
-		var sParams flowcontrol.ServerParams
-		if err := recv.get("flowControl/BL", &sParams.BufLimit); err != nil {
-			return err
-		}
-		if err := recv.get("flowControl/MRR", &sParams.MinRecharge); err != nil {
-			return err
-		}
-		var MRC RequestCostList
-		if err := recv.get("flowControl/MRC", &MRC); err != nil {
-			return err
-		}
-		p.fcParams = sParams
-		p.fcServer = flowcontrol.NewServerNode(sParams, &mclock.System{})
-		p.fcCosts = MRC.decode(ProtocolLengths[uint(p.version)])
+// clientPeerSubscriber is an interface to notify services about added or
+// removed client peers
+type clientPeerSubscriber interface {
+	registerPeer(*clientPeer)
+	unregisterPeer(*clientPeer)
+}
 
-		recv.get("checkpoint/value", &p.checkpoint)
-		recv.get("checkpoint/registerHeight", &p.checkpointNumber)
+// clientPeerSet represents the set of active client peers currently
+// participating in the Light Ethereum sub-protocol.
+type clientPeerSet struct {
+	peers map[string]*clientPeer
+	// subscribers is a batch of subscribers and peerset will notify
+	// these subscribers when the peerset changes(new client peer is
+	// added or removed)
+	subscribers []clientPeerSubscriber
+	closed      bool
+	lock        sync.RWMutex
+}
 
-		if !p.onlyAnnounce {
-			for msgCode := range reqAvgTimeCost {
-				if p.fcCosts[msgCode] == nil {
-					return errResp(ErrUselessPeer, "peer does not support message %d", msgCode)
-				}
-			}
+// newClientPeerSet creates a new peer set to track the client peers.
+func newClientPeerSet() *clientPeerSet {
+	return &clientPeerSet{peers: make(map[string]*clientPeer)}
+}
+
+// subscribe adds a service to be notified about added or removed
+// peers and also register all active peers into the given service.
+func (ps *clientPeerSet) subscribe(sub clientPeerSubscriber) {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	ps.subscribers = append(ps.subscribers, sub)
+	for _, p := range ps.peers {
+		sub.registerPeer(p)
+	}
+}
+
+// unSubscribe removes the specified service from the subscriber pool.
+func (ps *clientPeerSet) unSubscribe(sub clientPeerSubscriber) {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	for i, s := range ps.subscribers {
+		if s == sub {
+			ps.subscribers = append(ps.subscribers[:i], ps.subscribers[i+1:]...)
+			return
 		}
-		p.server = true
 	}
-	p.headInfo = &announceData{Td: rTd, Hash: rHash, Number: rNum}
+}
+
+// register adds a new peer into the peer set, or returns an error if the
+// peer is already known.
+func (ps *clientPeerSet) register(peer *clientPeer) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if ps.closed {
+		return errClosed
+	}
+	if _, exist := ps.peers[peer.id]; exist {
+		return errAlreadyRegistered
+	}
+	ps.peers[peer.id] = peer
+	for _, sub := range ps.subscribers {
+		sub.registerPeer(peer)
+	}
 	return nil
 }
 
-// updateFlowControl updates the flow control parameters belonging to the server
-// node if the announced key/value set contains relevant fields
-func (p *peer) updateFlowControl(update keyValueMap) {
-	if p.fcServer == nil {
-		return
+// unregister removes a remote peer from the peer set, disabling any further
+// actions to/from that particular entity. It also initiates disconnection
+// at the networking layer.
+func (ps *clientPeerSet) unregister(id string) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	p, ok := ps.peers[id]
+	if !ok {
+		return errNotRegistered
 	}
-	// If any of the flow control params is nil, refuse to update.
-	var params flowcontrol.ServerParams
-	if update.get("flowControl/BL", &params.BufLimit) == nil && update.get("flowControl/MRR", &params.MinRecharge) == nil {
-		// todo can light client set a minimal acceptable flow control params?
-		p.fcParams = params
-		p.fcServer.UpdateParams(params)
+	delete(ps.peers, id)
+	for _, sub := range ps.subscribers {
+		sub.unregisterPeer(p)
 	}
-	var MRC RequestCostList
-	if update.get("flowControl/MRC", &MRC) == nil {
-		costUpdate := MRC.decode(ProtocolLengths[uint(p.version)])
-		for code, cost := range costUpdate {
-			p.fcCosts[code] = cost
-		}
+	p.Peer.Disconnect(p2p.DiscRequested)
+	return nil
+}
+
+// ids returns a list of all registered peer IDs
+func (ps *clientPeerSet) ids() []string {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	var ids []string
+	for id := range ps.peers {
+		ids = append(ids, id)
 	}
+	return ids
 }
 
-// String implements fmt.Stringer.
-func (p *peer) String() string {
-	return fmt.Sprintf("Peer %s [%s]", p.id,
-		fmt.Sprintf("les/%d", p.version),
-	)
+// peer retrieves the registered peer with the given id.
+func (ps *clientPeerSet) peer(id string) *clientPeer {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	return ps.peers[id]
 }
 
-// peerSetNotify is a callback interface to notify services about added or
-// removed peers
-type peerSetNotify interface {
-	registerPeer(*peer)
-	unregisterPeer(*peer)
+// len returns if the current number of peers in the set.
+func (ps *clientPeerSet) len() int {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	return len(ps.peers)
 }
 
-// peerSet represents the collection of active peers currently participating in
-// the Light Ethereum sub-protocol.
-type peerSet struct {
-	peers      map[string]*peer
-	lock       sync.RWMutex
-	notifyList []peerSetNotify
-	closed     bool
+// allClientPeers returns all client peers in a list.
+func (ps *clientPeerSet) allPeers() []*clientPeer {
+	ps.lock.RLock()
+	defer ps.lock.RUnlock()
+
+	list := make([]*clientPeer, 0, len(ps.peers))
+	for _, p := range ps.peers {
+		list = append(list, p)
+	}
+	return list
 }
 
-// newPeerSet creates a new peer set to track the active participants.
-func newPeerSet() *peerSet {
-	return &peerSet{
-		peers: make(map[string]*peer),
+// close disconnects all peers. No new peers can be registered
+// after close has returned.
+func (ps *clientPeerSet) close() {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	for _, p := range ps.peers {
+		p.Disconnect(p2p.DiscQuitting)
 	}
+	ps.closed = true
+}
+
+// serverPeerSet represents the set of active server peers currently
+// participating in the Light Ethereum sub-protocol.
+type serverPeerSet struct {
+	peers map[string]*serverPeer
+	// subscribers is a batch of subscribers and peerset will notify
+	// these subscribers when the peerset changes(new server peer is
+	// added or removed)
+	subscribers []serverPeerSubscriber
+	closed      bool
+	lock        sync.RWMutex
+}
+
+// newServerPeerSet creates a new peer set to track the active server peers.
+func newServerPeerSet() *serverPeerSet {
+	return &serverPeerSet{peers: make(map[string]*serverPeer)}
 }
 
-// notify adds a service to be notified about added or removed peers
-func (ps *peerSet) notify(n peerSetNotify) {
+// subscribe adds a service to be notified about added or removed
+// peers and also register all active peers into the given service.
+func (ps *serverPeerSet) subscribe(sub serverPeerSubscriber) {
 	ps.lock.Lock()
-	ps.notifyList = append(ps.notifyList, n)
-	peers := make([]*peer, 0, len(ps.peers))
+	defer ps.lock.Unlock()
+
+	ps.subscribers = append(ps.subscribers, sub)
 	for _, p := range ps.peers {
-		peers = append(peers, p)
+		sub.registerPeer(p)
 	}
-	ps.lock.Unlock()
+}
 
-	for _, p := range peers {
-		n.registerPeer(p)
+// unSubscribe removes the specified service from the subscriber pool.
+func (ps *serverPeerSet) unSubscribe(sub serverPeerSubscriber) {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	for i, s := range ps.subscribers {
+		if s == sub {
+			ps.subscribers = append(ps.subscribers[:i], ps.subscribers[i+1:]...)
+			return
+		}
 	}
 }
 
-// Register injects a new peer into the working set, or returns an error if the
+// register adds a new server peer into the set, or returns an error if the
 // peer is already known.
-func (ps *peerSet) Register(p *peer) error {
+func (ps *serverPeerSet) register(peer *serverPeer) error {
 	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
 	if ps.closed {
-		ps.lock.Unlock()
 		return errClosed
 	}
-	if _, ok := ps.peers[p.id]; ok {
-		ps.lock.Unlock()
+	if _, exist := ps.peers[peer.id]; exist {
 		return errAlreadyRegistered
 	}
-	ps.peers[p.id] = p
-	p.sendQueue = newExecQueue(100)
-	peers := make([]peerSetNotify, len(ps.notifyList))
-	copy(peers, ps.notifyList)
-	ps.lock.Unlock()
-
-	for _, n := range peers {
-		n.registerPeer(p)
+	ps.peers[peer.id] = peer
+	for _, sub := range ps.subscribers {
+		sub.registerPeer(peer)
 	}
 	return nil
 }
 
-// Unregister removes a remote peer from the active set, disabling any further
-// actions to/from that particular entity. It also initiates disconnection at the networking layer.
-func (ps *peerSet) Unregister(id string) error {
+// unregister removes a remote peer from the active set, disabling any further
+// actions to/from that particular entity. It also initiates disconnection at
+// the networking layer.
+func (ps *serverPeerSet) unregister(id string) error {
 	ps.lock.Lock()
-	if p, ok := ps.peers[id]; !ok {
-		ps.lock.Unlock()
-		return errNotRegistered
-	} else {
-		delete(ps.peers, id)
-		peers := make([]peerSetNotify, len(ps.notifyList))
-		copy(peers, ps.notifyList)
-		ps.lock.Unlock()
-
-		for _, n := range peers {
-			n.unregisterPeer(p)
-		}
-
-		p.sendQueue.quit()
-		p.Peer.Disconnect(p2p.DiscUselessPeer)
+	defer ps.lock.Unlock()
 
-		return nil
+	p, ok := ps.peers[id]
+	if !ok {
+		return errNotRegistered
+	}
+	delete(ps.peers, id)
+	for _, sub := range ps.subscribers {
+		sub.unregisterPeer(p)
 	}
+	p.Peer.Disconnect(p2p.DiscRequested)
+	return nil
 }
 
-// AllPeerIDs returns a list of all registered peer IDs
-func (ps *peerSet) AllPeerIDs() []string {
+// ids returns a list of all registered peer IDs
+func (ps *serverPeerSet) ids() []string {
 	ps.lock.RLock()
 	defer ps.lock.RUnlock()
 
-	res := make([]string, len(ps.peers))
-	idx := 0
+	var ids []string
 	for id := range ps.peers {
-		res[idx] = id
-		idx++
+		ids = append(ids, id)
 	}
-	return res
+	return ids
 }
 
-// Peer retrieves the registered peer with the given id.
-func (ps *peerSet) Peer(id string) *peer {
+// peer retrieves the registered peer with the given id.
+func (ps *serverPeerSet) peer(id string) *serverPeer {
 	ps.lock.RLock()
 	defer ps.lock.RUnlock()
 
 	return ps.peers[id]
 }
 
-// Len returns if the current number of peers in the set.
-func (ps *peerSet) Len() int {
+// len returns if the current number of peers in the set.
+func (ps *serverPeerSet) len() int {
 	ps.lock.RLock()
 	defer ps.lock.RUnlock()
 
 	return len(ps.peers)
 }
 
-// BestPeer retrieves the known peer with the currently highest total difficulty.
-func (ps *peerSet) BestPeer() *peer {
+// bestPeer retrieves the known peer with the currently highest total difficulty.
+// If the peerset is "client peer set", then nothing meaningful will return. The
+// reason is client peer never send back their latest status to server.
+func (ps *serverPeerSet) bestPeer() *serverPeer {
 	ps.lock.RLock()
 	defer ps.lock.RUnlock()
 
 	var (
-		bestPeer *peer
+		bestPeer *serverPeer
 		bestTd   *big.Int
 	)
 	for _, p := range ps.peers {
-		if td := p.Td(); bestPeer == nil || td.Cmp(bestTd) > 0 {
+		if td := p.Td(); bestTd == nil || td.Cmp(bestTd) > 0 {
 			bestPeer, bestTd = p, td
 		}
 	}
 	return bestPeer
 }
 
-// AllPeers returns all peers in a list
-func (ps *peerSet) AllPeers() []*peer {
+// allServerPeers returns all server peers in a list.
+func (ps *serverPeerSet) allPeers() []*serverPeer {
 	ps.lock.RLock()
 	defer ps.lock.RUnlock()
 
-	list := make([]*peer, len(ps.peers))
-	i := 0
-	for _, peer := range ps.peers {
-		list[i] = peer
-		i++
+	list := make([]*serverPeer, 0, len(ps.peers))
+	for _, p := range ps.peers {
+		list = append(list, p)
 	}
 	return list
 }
 
-// Close disconnects all peers.
-// No new peers can be registered after Close has returned.
-func (ps *peerSet) Close() {
+// close disconnects all peers. No new peers can be registered
+// after close has returned.
+func (ps *serverPeerSet) close() {
 	ps.lock.Lock()
 	defer ps.lock.Unlock()
 
diff --git a/les/peer_test.go b/les/peer_test.go
index db74a052c1..59a2ad7009 100644
--- a/les/peer_test.go
+++ b/les/peer_test.go
@@ -17,286 +17,131 @@
 package les
 
 import (
+	"crypto/rand"
 	"math/big"
-	"net"
+	"reflect"
+	"sort"
 	"testing"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/common/mclock"
-	"github.com/ethereum/go-ethereum/core/rawdb"
-	"github.com/ethereum/go-ethereum/crypto"
-	"github.com/ethereum/go-ethereum/eth"
-	"github.com/ethereum/go-ethereum/les/flowcontrol"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/enode"
-	"github.com/ethereum/go-ethereum/rlp"
 )
 
-const protocolVersion = lpv2
-
-var (
-	hash    = common.HexToHash("deadbeef")
-	genesis = common.HexToHash("cafebabe")
-	headNum = uint64(1234)
-	td      = big.NewInt(123)
-)
-
-func newNodeID(t *testing.T) *enode.Node {
-	key, err := crypto.GenerateKey()
-	if err != nil {
-		t.Fatal("generate key err:", err)
-	}
-	return enode.NewV4(&key.PublicKey, net.IP{}, 35000, 35000)
-}
-
-// ulc connects to trusted peer and send announceType=announceTypeSigned
-func TestPeerHandshakeSetAnnounceTypeToAnnounceTypeSignedForTrustedPeer(t *testing.T) {
-	id := newNodeID(t).ID()
-
-	// peer to connect(on ulc side)
-	p := peer{
-		Peer:    p2p.NewPeer(id, "test peer", []p2p.Cap{}),
-		version: protocolVersion,
-		trusted: true,
-		rw: &rwStub{
-			WriteHook: func(recvList keyValueList) {
-				recv, _ := recvList.decode()
-				var reqType uint64
-				err := recv.get("announceType", &reqType)
-				if err != nil {
-					t.Fatal(err)
-				}
-				if reqType != announceTypeSigned {
-					t.Fatal("Expected announceTypeSigned")
-				}
-			},
-			ReadHook: func(l keyValueList) keyValueList {
-				l = l.add("serveHeaders", nil)
-				l = l.add("serveChainSince", uint64(0))
-				l = l.add("serveStateSince", uint64(0))
-				l = l.add("txRelay", nil)
-				l = l.add("flowControl/BL", uint64(0))
-				l = l.add("flowControl/MRR", uint64(0))
-				l = l.add("flowControl/MRC", testCostList(0))
-				return l
-			},
-		},
-		network: NetworkId,
-	}
-	err := p.Handshake(td, hash, headNum, genesis, nil)
-	if err != nil {
-		t.Fatalf("Handshake error: %s", err)
-	}
-	if p.announceType != announceTypeSigned {
-		t.Fatal("Incorrect announceType")
-	}
-}
-
-func TestPeerHandshakeAnnounceTypeSignedForTrustedPeersPeerNotInTrusted(t *testing.T) {
-	id := newNodeID(t).ID()
-	p := peer{
-		Peer:    p2p.NewPeer(id, "test peer", []p2p.Cap{}),
-		version: protocolVersion,
-		rw: &rwStub{
-			WriteHook: func(recvList keyValueList) {
-				// checking that ulc sends to peer allowedRequests=noRequests and announceType != announceTypeSigned
-				recv, _ := recvList.decode()
-				var reqType uint64
-				err := recv.get("announceType", &reqType)
-				if err != nil {
-					t.Fatal(err)
-				}
-				if reqType == announceTypeSigned {
-					t.Fatal("Expected not announceTypeSigned")
-				}
-			},
-			ReadHook: func(l keyValueList) keyValueList {
-				l = l.add("serveHeaders", nil)
-				l = l.add("serveChainSince", uint64(0))
-				l = l.add("serveStateSince", uint64(0))
-				l = l.add("txRelay", nil)
-				l = l.add("flowControl/BL", uint64(0))
-				l = l.add("flowControl/MRR", uint64(0))
-				l = l.add("flowControl/MRC", testCostList(0))
-				return l
-			},
-		},
-		network: NetworkId,
-	}
-	err := p.Handshake(td, hash, headNum, genesis, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if p.announceType == announceTypeSigned {
-		t.Fatal("Incorrect announceType")
-	}
-}
-
-func TestPeerHandshakeDefaultAllRequests(t *testing.T) {
-	id := newNodeID(t).ID()
-
-	s := generateLesServer()
-
-	p := peer{
-		Peer:    p2p.NewPeer(id, "test peer", []p2p.Cap{}),
-		version: protocolVersion,
-		rw: &rwStub{
-			ReadHook: func(l keyValueList) keyValueList {
-				l = l.add("announceType", uint64(announceTypeSigned))
-				l = l.add("allowedRequests", uint64(0))
-				return l
-			},
-		},
-		network: NetworkId,
-	}
-
-	err := p.Handshake(td, hash, headNum, genesis, s)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if p.onlyAnnounce {
-		t.Fatal("Incorrect announceType")
-	}
-}
-
-func TestPeerHandshakeServerSendOnlyAnnounceRequestsHeaders(t *testing.T) {
-	id := newNodeID(t).ID()
-
-	s := generateLesServer()
-	s.config.UltraLightOnlyAnnounce = true
-
-	p := peer{
-		Peer:    p2p.NewPeer(id, "test peer", []p2p.Cap{}),
-		version: protocolVersion,
-		rw: &rwStub{
-			ReadHook: func(l keyValueList) keyValueList {
-				l = l.add("announceType", uint64(announceTypeSigned))
-				return l
-			},
-			WriteHook: func(l keyValueList) {
-				for _, v := range l {
-					if v.Key == "serveHeaders" ||
-						v.Key == "serveChainSince" ||
-						v.Key == "serveStateSince" ||
-						v.Key == "txRelay" {
-						t.Fatalf("%v exists", v.Key)
-					}
-				}
-			},
-		},
-		network: NetworkId,
-	}
-
-	err := p.Handshake(td, hash, headNum, genesis, s)
-	if err != nil {
-		t.Fatal(err)
-	}
-}
-func TestPeerHandshakeClientReceiveOnlyAnnounceRequestsHeaders(t *testing.T) {
-	id := newNodeID(t).ID()
-
-	p := peer{
-		Peer:    p2p.NewPeer(id, "test peer", []p2p.Cap{}),
-		version: protocolVersion,
-		rw: &rwStub{
-			ReadHook: func(l keyValueList) keyValueList {
-				l = l.add("flowControl/BL", uint64(0))
-				l = l.add("flowControl/MRR", uint64(0))
-				l = l.add("flowControl/MRC", RequestCostList{})
-
-				l = l.add("announceType", uint64(announceTypeSigned))
-
-				return l
-			},
-		},
-		network: NetworkId,
-		trusted: true,
-	}
-
-	err := p.Handshake(td, hash, headNum, genesis, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	if !p.onlyAnnounce {
-		t.Fatal("onlyAnnounce must be true")
-	}
-}
-
-func TestPeerHandshakeClientReturnErrorOnUselessPeer(t *testing.T) {
-	id := newNodeID(t).ID()
-
-	p := peer{
-		Peer:    p2p.NewPeer(id, "test peer", []p2p.Cap{}),
-		version: protocolVersion,
-		rw: &rwStub{
-			ReadHook: func(l keyValueList) keyValueList {
-				l = l.add("flowControl/BL", uint64(0))
-				l = l.add("flowControl/MRR", uint64(0))
-				l = l.add("flowControl/MRC", RequestCostList{})
-				l = l.add("announceType", uint64(announceTypeSigned))
-				return l
-			},
-		},
-		network: NetworkId,
-	}
-
-	err := p.Handshake(td, hash, headNum, genesis, nil)
-	if err == nil {
-		t.FailNow()
-	}
+type testServerPeerSub struct {
+	regCh   chan *serverPeer
+	unregCh chan *serverPeer
 }
 
-func generateLesServer() *LesServer {
-	s := &LesServer{
-		lesCommons: lesCommons{
-			config: &eth.Config{UltraLightOnlyAnnounce: true},
-		},
-		defParams: flowcontrol.ServerParams{
-			BufLimit:    uint64(300000000),
-			MinRecharge: uint64(50000),
-		},
-		fcManager: flowcontrol.NewClientManager(nil, &mclock.System{}),
+func newTestServerPeerSub() *testServerPeerSub {
+	return &testServerPeerSub{
+		regCh:   make(chan *serverPeer, 1),
+		unregCh: make(chan *serverPeer, 1),
 	}
-	s.costTracker, _ = newCostTracker(rawdb.NewMemoryDatabase(), s.config)
-	return s
 }
 
-type rwStub struct {
-	ReadHook  func(l keyValueList) keyValueList
-	WriteHook func(l keyValueList)
+func (t *testServerPeerSub) registerPeer(p *serverPeer)   { t.regCh <- p }
+func (t *testServerPeerSub) unregisterPeer(p *serverPeer) { t.unregCh <- p }
+
+func TestPeerSubscription(t *testing.T) {
+	peers := newServerPeerSet()
+	defer peers.close()
+
+	checkIds := func(expect []string) {
+		given := peers.ids()
+		if len(given) == 0 && len(expect) == 0 {
+			return
+		}
+		sort.Strings(given)
+		sort.Strings(expect)
+		if !reflect.DeepEqual(given, expect) {
+			t.Fatalf("all peer ids mismatch, want %v, given %v", expect, given)
+		}
+	}
+	checkPeers := func(peerCh chan *serverPeer) {
+		select {
+		case <-peerCh:
+		case <-time.NewTimer(100 * time.Millisecond).C:
+			t.Fatalf("timeout, no event received")
+		}
+		select {
+		case <-peerCh:
+			t.Fatalf("unexpected event received")
+		case <-time.NewTimer(10 * time.Millisecond).C:
+		}
+	}
+	checkIds([]string{})
+
+	sub := newTestServerPeerSub()
+	peers.subscribe(sub)
+
+	// Generate a random id and create the peer
+	var id enode.ID
+	rand.Read(id[:])
+	peer := newServerPeer(2, NetworkId, false, p2p.NewPeer(id, "name", nil), nil)
+	peers.register(peer)
+
+	checkIds([]string{peer.id})
+	checkPeers(sub.regCh)
+
+	peers.unregister(peer.id)
+	checkIds([]string{})
+	checkPeers(sub.unregCh)
 }
 
-func (s *rwStub) ReadMsg() (p2p.Msg, error) {
-	payload := keyValueList{}
-	payload = payload.add("protocolVersion", uint64(protocolVersion))
-	payload = payload.add("networkId", uint64(NetworkId))
-	payload = payload.add("headTd", td)
-	payload = payload.add("headHash", hash)
-	payload = payload.add("headNum", headNum)
-	payload = payload.add("genesisHash", genesis)
-
-	if s.ReadHook != nil {
-		payload = s.ReadHook(payload)
-	}
-	size, p, err := rlp.EncodeToReader(payload)
-	if err != nil {
-		return p2p.Msg{}, err
-	}
-	return p2p.Msg{
-		Size:    uint32(size),
-		Payload: p,
-	}, nil
-}
-
-func (s *rwStub) WriteMsg(m p2p.Msg) error {
-	recvList := keyValueList{}
-	if err := m.Decode(&recvList); err != nil {
-		return err
-	}
-	if s.WriteHook != nil {
-		s.WriteHook(recvList)
+func TestHandshake(t *testing.T) {
+	// Create a message pipe to communicate through
+	app, net := p2p.MsgPipe()
+
+	// Generate a random id and create the peer
+	var id enode.ID
+	rand.Read(id[:])
+
+	peer1 := newClientPeer(2, NetworkId, p2p.NewPeer(id, "name", nil), net)
+	peer2 := newServerPeer(2, NetworkId, true, p2p.NewPeer(id, "name", nil), app)
+
+	var (
+		errCh1 = make(chan error, 1)
+		errCh2 = make(chan error, 1)
+
+		td      = big.NewInt(100)
+		head    = common.HexToHash("deadbeef")
+		headNum = uint64(10)
+		genesis = common.HexToHash("cafebabe")
+	)
+	go func() {
+		errCh1 <- peer1.handshake(td, head, headNum, genesis, func(list *keyValueList) {
+			var announceType uint64 = announceTypeSigned
+			*list = (*list).add("announceType", announceType)
+		}, nil)
+	}()
+	go func() {
+		errCh2 <- peer2.handshake(td, head, headNum, genesis, nil, func(recv keyValueMap) error {
+			var reqType uint64
+			err := recv.get("announceType", &reqType)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if reqType != announceTypeSigned {
+				t.Fatal("Expected announceTypeSigned")
+			}
+			return nil
+		})
+	}()
+
+	for i := 0; i < 2; i++ {
+		select {
+		case err := <-errCh1:
+			if err != nil {
+				t.Fatalf("handshake failed, %v", err)
+			}
+		case err := <-errCh2:
+			if err != nil {
+				t.Fatalf("handshake failed, %v", err)
+			}
+		case <-time.NewTimer(100 * time.Millisecond).C:
+			t.Fatalf("timeout")
+		}
 	}
-	return nil
 }
diff --git a/les/request_test.go b/les/request_test.go
index 8d09703c57..f58ebca9c1 100644
--- a/les/request_test.go
+++ b/les/request_test.go
@@ -81,8 +81,7 @@ func testAccess(t *testing.T, protocol int, fn accessTestFn) {
 	// Assemble the test environment
 	server, client, tearDown := newClientServerEnv(t, 4, protocol, nil, nil, 0, false, true)
 	defer tearDown()
-
-	client.handler.synchronise(client.peer.peer)
+	client.handler.synchronise(client.peer.speer)
 
 	// Ensure the client has synced all necessary data.
 	clientHead := client.handler.backend.blockchain.CurrentHeader()
diff --git a/les/retrieve.go b/les/retrieve.go
index c806117902..5fa68b7456 100644
--- a/les/retrieve.go
+++ b/les/retrieve.go
@@ -38,7 +38,7 @@ var (
 // matching replies by request ID and handles timeouts and resends if necessary.
 type retrieveManager struct {
 	dist       *requestDistributor
-	peers      *peerSet
+	peers      *serverPeerSet
 	serverPool peerSelector
 
 	lock     sync.RWMutex
@@ -99,7 +99,7 @@ const (
 )
 
 // newRetrieveManager creates the retrieve manager
-func newRetrieveManager(peers *peerSet, dist *requestDistributor, serverPool peerSelector) *retrieveManager {
+func newRetrieveManager(peers *serverPeerSet, dist *requestDistributor, serverPool peerSelector) *retrieveManager {
 	return &retrieveManager{
 		peers:      peers,
 		dist:       dist,
@@ -337,7 +337,7 @@ func (r *sentReq) tryRequest() {
 
 	defer func() {
 		// send feedback to server pool and remove peer if hard timeout happened
-		pp, ok := p.(*peer)
+		pp, ok := p.(*serverPeer)
 		if ok && r.rm.serverPool != nil {
 			respTime := time.Duration(mclock.Now() - reqSent)
 			r.rm.serverPool.adjustResponseTime(pp.poolEntry, respTime, srto)
@@ -345,7 +345,7 @@ func (r *sentReq) tryRequest() {
 		if hrto {
 			pp.Log().Debug("Request timed out hard")
 			if r.rm.peers != nil {
-				r.rm.peers.Unregister(pp.id)
+				r.rm.peers.unregister(pp.id)
 			}
 		}
 
diff --git a/les/server.go b/les/server.go
index 664eba9717..f72f31321a 100644
--- a/les/server.go
+++ b/les/server.go
@@ -40,6 +40,7 @@ type LesServer struct {
 	lesCommons
 
 	archiveMode bool // Flag whether the ethereum node runs in archive mode.
+	peers       *clientPeerSet
 	handler     *serverHandler
 	lesTopics   []discv5.Topic
 	privateKey  *ecdsa.PrivateKey
@@ -75,13 +76,13 @@ func NewLesServer(e *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 			chainConfig:      e.BlockChain().Config(),
 			iConfig:          light.DefaultServerIndexerConfig,
 			chainDb:          e.ChainDb(),
-			peers:            newPeerSet(),
 			chainReader:      e.BlockChain(),
 			chtIndexer:       light.NewChtIndexer(e.ChainDb(), nil, params.CHTFrequency, params.HelperTrieProcessConfirmations),
 			bloomTrieIndexer: light.NewBloomTrieIndexer(e.ChainDb(), nil, params.BloomBitsBlocks, params.BloomTrieFrequency),
 			closeCh:          make(chan struct{}),
 		},
 		archiveMode:  e.ArchiveMode(),
+		peers:        newClientPeerSet(),
 		lesTopics:    lesTopics,
 		fcManager:    flowcontrol.NewClientManager(nil, &mclock.System{}),
 		servingQueue: newServingQueue(int64(time.Millisecond*10), float64(config.LightServ)/100),
@@ -115,7 +116,7 @@ func NewLesServer(e *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 		srv.maxCapacity = totalRecharge
 	}
 	srv.fcManager.SetCapacityLimits(srv.freeCapacity, srv.maxCapacity, srv.freeCapacity*2)
-	srv.clientPool = newClientPool(srv.chainDb, srv.freeCapacity, mclock.System{}, func(id enode.ID) { go srv.peers.Unregister(peerIdToString(id)) })
+	srv.clientPool = newClientPool(srv.chainDb, srv.freeCapacity, mclock.System{}, func(id enode.ID) { go srv.peers.unregister(peerIdToString(id)) })
 	srv.clientPool.setDefaultFactors(priceFactors{0, 1, 1}, priceFactors{0, 1, 1})
 
 	checkpoint := srv.latestLocalCheckpoint()
@@ -152,7 +153,7 @@ func (s *LesServer) APIs() []rpc.API {
 
 func (s *LesServer) Protocols() []p2p.Protocol {
 	ps := s.makeProtocols(ServerProtocolVersions, s.handler.runPeer, func(id enode.ID) interface{} {
-		if p := s.peers.Peer(peerIdToString(id)); p != nil {
+		if p := s.peers.peer(peerIdToString(id)); p != nil {
 			return p.Info()
 		}
 		return nil
@@ -194,7 +195,7 @@ func (s *LesServer) Stop() {
 	// This also closes the gate for any new registrations on the peer set.
 	// sessions which are already established but not added to pm.peers yet
 	// will exit when they try to register.
-	s.peers.Close()
+	s.peers.close()
 
 	s.fcManager.Stop()
 	s.costTracker.stop()
diff --git a/les/server_handler.go b/les/server_handler.go
index 98e9294b07..186bdcbb03 100644
--- a/les/server_handler.go
+++ b/les/server_handler.go
@@ -101,13 +101,14 @@ func (h *serverHandler) stop() {
 
 // runPeer is the p2p protocol run function for the given version.
 func (h *serverHandler) runPeer(version uint, p *p2p.Peer, rw p2p.MsgReadWriter) error {
-	peer := newPeer(int(version), h.server.config.NetworkId, false, p, newMeteredMsgWriter(rw, int(version)))
+	peer := newClientPeer(int(version), h.server.config.NetworkId, p, newMeteredMsgWriter(rw, int(version)))
+	defer peer.close()
 	h.wg.Add(1)
 	defer h.wg.Done()
 	return h.handle(peer)
 }
 
-func (h *serverHandler) handle(p *peer) error {
+func (h *serverHandler) handle(p *clientPeer) error {
 	p.Log().Debug("Light Ethereum peer connected", "name", p.Name())
 
 	// Execute the LES handshake
@@ -139,21 +140,21 @@ func (h *serverHandler) handle(p *peer) error {
 		return errFullClientPool
 	}
 	// Register the peer locally
-	if err := h.server.peers.Register(p); err != nil {
+	if err := h.server.peers.register(p); err != nil {
 		h.server.clientPool.disconnect(p)
 		p.Log().Error("Light Ethereum peer registration failed", "err", err)
 		return err
 	}
-	clientConnectionGauge.Update(int64(h.server.peers.Len()))
+	clientConnectionGauge.Update(int64(h.server.peers.len()))
 
 	var wg sync.WaitGroup // Wait group used to track all in-flight task routines.
 
 	connectedAt := mclock.Now()
 	defer func() {
 		wg.Wait() // Ensure all background task routines have exited.
-		h.server.peers.Unregister(p.id)
+		h.server.peers.unregister(p.id)
 		h.server.clientPool.disconnect(p)
-		clientConnectionGauge.Update(int64(h.server.peers.Len()))
+		clientConnectionGauge.Update(int64(h.server.peers.len()))
 		connectionTimer.Update(time.Duration(mclock.Now() - connectedAt))
 	}()
 
@@ -174,7 +175,7 @@ func (h *serverHandler) handle(p *peer) error {
 
 // handleMsg is invoked whenever an inbound message is received from a remote
 // peer. The remote connection is torn down upon returning any error.
-func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
+func (h *serverHandler) handleMsg(p *clientPeer, wg *sync.WaitGroup) error {
 	// Read the next message from the remote peer, and ensure it's fully consumed
 	msg, err := p.rw.ReadMsg()
 	if err != nil {
@@ -208,7 +209,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 		maxCost = p.fcCosts.getMaxCost(msg.Code, reqCnt)
 		accepted, bufShort, priority := p.fcClient.AcceptRequest(reqID, responseCount, maxCost)
 		if !accepted {
-			p.freezeClient()
+			p.freeze()
 			p.Log().Error("Request came too early", "remaining", common.PrettyDuration(time.Duration(bufShort*1000000/p.fcParams.MinRecharge)))
 			p.fcClient.OneTimeCost(inSizeCost)
 			return false
@@ -258,7 +259,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 			h.server.clientPool.requestCost(p, realCost)
 		}
 		if reply != nil {
-			p.queueSend(func() {
+			p.mustQueueSend(func() {
 				if err := reply.send(bv); err != nil {
 					select {
 					case p.errCh <- err:
@@ -372,8 +373,8 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 					}
 					first = false
 				}
-				reply := p.ReplyBlockHeaders(req.ReqID, headers)
-				sendResponse(req.ReqID, query.Amount, p.ReplyBlockHeaders(req.ReqID, headers), task.done())
+				reply := p.replyBlockHeaders(req.ReqID, headers)
+				sendResponse(req.ReqID, query.Amount, p.replyBlockHeaders(req.ReqID, headers), task.done())
 				if metrics.EnabledExpensive {
 					miscOutHeaderPacketsMeter.Mark(1)
 					miscOutHeaderTrafficMeter.Mark(int64(reply.size()))
@@ -421,7 +422,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 					bodies = append(bodies, body)
 					bytes += len(body)
 				}
-				reply := p.ReplyBlockBodiesRLP(req.ReqID, bodies)
+				reply := p.replyBlockBodiesRLP(req.ReqID, bodies)
 				sendResponse(req.ReqID, uint64(reqCnt), reply, task.done())
 				if metrics.EnabledExpensive {
 					miscOutBodyPacketsMeter.Mark(1)
@@ -493,7 +494,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 						break
 					}
 				}
-				reply := p.ReplyCode(req.ReqID, data)
+				reply := p.replyCode(req.ReqID, data)
 				sendResponse(req.ReqID, uint64(reqCnt), reply, task.done())
 				if metrics.EnabledExpensive {
 					miscOutCodePacketsMeter.Mark(1)
@@ -550,7 +551,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 						bytes += len(encoded)
 					}
 				}
-				reply := p.ReplyReceiptsRLP(req.ReqID, receipts)
+				reply := p.replyReceiptsRLP(req.ReqID, receipts)
 				sendResponse(req.ReqID, uint64(reqCnt), reply, task.done())
 				if metrics.EnabledExpensive {
 					miscOutReceiptPacketsMeter.Mark(1)
@@ -653,7 +654,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 						break
 					}
 				}
-				reply := p.ReplyProofsV2(req.ReqID, nodes.NodeList())
+				reply := p.replyProofsV2(req.ReqID, nodes.NodeList())
 				sendResponse(req.ReqID, uint64(reqCnt), reply, task.done())
 				if metrics.EnabledExpensive {
 					miscOutTrieProofPacketsMeter.Mark(1)
@@ -728,7 +729,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 						break
 					}
 				}
-				reply := p.ReplyHelperTrieProofs(req.ReqID, HelperTrieResps{Proofs: nodes.NodeList(), AuxData: auxData})
+				reply := p.replyHelperTrieProofs(req.ReqID, HelperTrieResps{Proofs: nodes.NodeList(), AuxData: auxData})
 				sendResponse(req.ReqID, uint64(reqCnt), reply, task.done())
 				if metrics.EnabledExpensive {
 					miscOutHelperTriePacketsMeter.Mark(1)
@@ -777,7 +778,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 						stats[i] = h.txStatus(hash)
 					}
 				}
-				reply := p.ReplyTxStatus(req.ReqID, stats)
+				reply := p.replyTxStatus(req.ReqID, stats)
 				sendResponse(req.ReqID, uint64(reqCnt), reply, task.done())
 				if metrics.EnabledExpensive {
 					miscOutTxsPacketsMeter.Mark(1)
@@ -814,7 +815,7 @@ func (h *serverHandler) handleMsg(p *peer, wg *sync.WaitGroup) error {
 					}
 					stats[i] = h.txStatus(hash)
 				}
-				reply := p.ReplyTxStatus(req.ReqID, stats)
+				reply := p.replyTxStatus(req.ReqID, stats)
 				sendResponse(req.ReqID, uint64(reqCnt), reply, task.done())
 				if metrics.EnabledExpensive {
 					miscOutTxStatusPacketsMeter.Mark(1)
@@ -913,7 +914,7 @@ func (h *serverHandler) broadcastHeaders() {
 	for {
 		select {
 		case ev := <-headCh:
-			peers := h.server.peers.AllPeers()
+			peers := h.server.peers.allPeers()
 			if len(peers) == 0 {
 				continue
 			}
@@ -939,14 +940,18 @@ func (h *serverHandler) broadcastHeaders() {
 				p := p
 				switch p.announceType {
 				case announceTypeSimple:
-					p.queueSend(func() { p.SendAnnounce(announce) })
+					if !p.queueSend(func() { p.sendAnnounce(announce) }) {
+						log.Debug("Drop announcement because queue is full", "number", number, "hash", hash)
+					}
 				case announceTypeSigned:
 					if !signed {
 						signedAnnounce = announce
 						signedAnnounce.sign(h.server.privateKey)
 						signed = true
 					}
-					p.queueSend(func() { p.SendAnnounce(signedAnnounce) })
+					if !p.queueSend(func() { p.sendAnnounce(signedAnnounce) }) {
+						log.Debug("Drop announcement because queue is full", "number", number, "hash", hash)
+					}
 				}
 			}
 		case <-h.closeCh:
diff --git a/les/serverpool.go b/les/serverpool.go
index f8fd721696..ec99a2d982 100644
--- a/les/serverpool.go
+++ b/les/serverpool.go
@@ -90,7 +90,7 @@ const (
 
 // connReq represents a request for peer connection.
 type connReq struct {
-	p      *peer
+	p      *serverPeer
 	node   *enode.Node
 	result chan *poolEntry
 }
@@ -220,7 +220,7 @@ func (pool *serverPool) discoverNodes() {
 // Otherwise, the connection should be rejected.
 // Note that whenever a connection has been accepted and a pool entry has been returned,
 // disconnect should also always be called.
-func (pool *serverPool) connect(p *peer, node *enode.Node) *poolEntry {
+func (pool *serverPool) connect(p *serverPeer, node *enode.Node) *poolEntry {
 	log.Debug("Connect new entry", "enode", p.id)
 	req := &connReq{p: p, node: node, result: make(chan *poolEntry, 1)}
 	select {
@@ -679,7 +679,7 @@ const (
 
 // poolEntry represents a server node and stores its current state and statistics.
 type poolEntry struct {
-	peer                  *peer
+	peer                  *serverPeer
 	pubkey                [64]byte // secp256k1 key of the node
 	addr                  map[string]*poolEntryAddress
 	node                  *enode.Node
diff --git a/les/servingqueue.go b/les/servingqueue.go
index 8842cf9e9d..9db84e6159 100644
--- a/les/servingqueue.go
+++ b/les/servingqueue.go
@@ -55,7 +55,7 @@ type servingQueue struct {
 type servingTask struct {
 	sq                                       *servingQueue
 	servingTime, timeAdded, maxTime, expTime uint64
-	peer                                     *peer
+	peer                                     *clientPeer
 	priority                                 int64
 	biasAdded                                bool
 	token                                    runToken
@@ -142,7 +142,7 @@ func newServingQueue(suspendBias int64, utilTarget float64) *servingQueue {
 }
 
 // newTask creates a new task with the given priority
-func (sq *servingQueue) newTask(peer *peer, maxTime uint64, priority int64) *servingTask {
+func (sq *servingQueue) newTask(peer *clientPeer, maxTime uint64, priority int64) *servingTask {
 	return &servingTask{
 		sq:       sq,
 		peer:     peer,
@@ -187,7 +187,7 @@ func (sq *servingQueue) threadController() {
 type (
 	// peerTasks lists the tasks received from a given peer when selecting peers to freeze
 	peerTasks struct {
-		peer     *peer
+		peer     *clientPeer
 		list     []*servingTask
 		sumTime  uint64
 		priority float64
@@ -211,7 +211,7 @@ func (l peerList) Swap(i, j int) {
 // freezePeers selects the peers with the worst priority queued tasks and freezes
 // them until burstTime goes under burstDropLimit or all peers are frozen
 func (sq *servingQueue) freezePeers() {
-	peerMap := make(map[*peer]*peerTasks)
+	peerMap := make(map[*clientPeer]*peerTasks)
 	var peerList peerList
 	if sq.best != nil {
 		sq.queue.Push(sq.best, sq.best.priority)
@@ -239,7 +239,7 @@ func (sq *servingQueue) freezePeers() {
 	drop := true
 	for _, tasks := range peerList {
 		if drop {
-			tasks.peer.freezeClient()
+			tasks.peer.freeze()
 			tasks.peer.fcClient.Freeze()
 			sq.queuedTime -= tasks.sumTime
 			sqQueuedGauge.Update(int64(sq.queuedTime))
diff --git a/les/sync.go b/les/sync.go
index 207686403f..d2568d45bc 100644
--- a/les/sync.go
+++ b/les/sync.go
@@ -51,7 +51,7 @@ const (
 // In addition to the checkpoint registered in the registrar contract, there are
 // several legacy hardcoded checkpoints in our codebase. These checkpoints are
 // also considered as valid.
-func (h *clientHandler) validateCheckpoint(peer *peer) error {
+func (h *clientHandler) validateCheckpoint(peer *serverPeer) error {
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
 	defer cancel()
 
@@ -87,7 +87,7 @@ func (h *clientHandler) validateCheckpoint(peer *peer) error {
 }
 
 // synchronise tries to sync up our local chain with a remote peer.
-func (h *clientHandler) synchronise(peer *peer) {
+func (h *clientHandler) synchronise(peer *serverPeer) {
 	// Short circuit if the peer is nil.
 	if peer == nil {
 		return
@@ -95,7 +95,7 @@ func (h *clientHandler) synchronise(peer *peer) {
 	// Make sure the peer's TD is higher than our own.
 	latest := h.backend.blockchain.CurrentHeader()
 	currentTd := rawdb.ReadTd(h.backend.chainDb, latest.Hash(), latest.Number.Uint64())
-	if currentTd != nil && peer.headBlockInfo().Td.Cmp(currentTd) < 0 {
+	if currentTd != nil && peer.Td().Cmp(currentTd) < 0 {
 		return
 	}
 	// Recap the checkpoint.
diff --git a/les/sync_test.go b/les/sync_test.go
index 1c157b4fbf..77b82deb7a 100644
--- a/les/sync_test.go
+++ b/les/sync_test.go
@@ -109,7 +109,9 @@ func testCheckpointSyncing(t *testing.T, protocol int, syncMode int) {
 	}
 
 	// Create connected peer pair.
-	_, err1, _, err2 := newTestPeerPair("peer", protocol, server.handler, client.handler)
+	peer1, err1, peer2, err2 := newTestPeerPair("peer", protocol, server.handler, client.handler)
+	defer peer1.close()
+	defer peer2.close()
 	select {
 	case <-time.After(time.Millisecond * 100):
 	case err := <-err1:
diff --git a/les/test_helper.go b/les/test_helper.go
index fb1965eebe..d9ffe32db2 100644
--- a/les/test_helper.go
+++ b/les/test_helper.go
@@ -166,7 +166,7 @@ func testIndexers(db ethdb.Database, odr light.OdrBackend, config *light.Indexer
 	return indexers[:]
 }
 
-func newTestClientHandler(backend *backends.SimulatedBackend, odr *LesOdr, indexers []*core.ChainIndexer, db ethdb.Database, peers *peerSet, ulcServers []string, ulcFraction int) *clientHandler {
+func newTestClientHandler(backend *backends.SimulatedBackend, odr *LesOdr, indexers []*core.ChainIndexer, db ethdb.Database, peers *serverPeerSet, ulcServers []string, ulcFraction int) *clientHandler {
 	var (
 		evmux  = new(event.TypeMux)
 		engine = ethash.NewFaker()
@@ -206,9 +206,9 @@ func newTestClientHandler(backend *backends.SimulatedBackend, odr *LesOdr, index
 			chainDb:     db,
 			oracle:      oracle,
 			chainReader: chain,
-			peers:       peers,
 			closeCh:     make(chan struct{}),
 		},
+		peers:      peers,
 		reqDist:    odr.retriever.dist,
 		retriever:  odr.retriever,
 		odr:        odr,
@@ -224,7 +224,7 @@ func newTestClientHandler(backend *backends.SimulatedBackend, odr *LesOdr, index
 	return client.handler
 }
 
-func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Database, peers *peerSet, clock mclock.Clock) (*serverHandler, *backends.SimulatedBackend) {
+func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Database, peers *clientPeerSet, clock mclock.Clock) (*serverHandler, *backends.SimulatedBackend) {
 	var (
 		gspec = core.Genesis{
 			Config:   params.AllEthashProtocolChanges,
@@ -269,9 +269,9 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 			chainDb:     db,
 			chainReader: simulation.Blockchain(),
 			oracle:      oracle,
-			peers:       peers,
 			closeCh:     make(chan struct{}),
 		},
+		peers:        peers,
 		servingQueue: newServingQueue(int64(time.Millisecond*10), 1),
 		defParams: flowcontrol.ServerParams{
 			BufLimit:    testBufLimit,
@@ -294,7 +294,8 @@ func newTestServerHandler(blocks int, indexers []*core.ChainIndexer, db ethdb.Da
 
 // testPeer is a simulated peer to allow testing direct network calls.
 type testPeer struct {
-	peer *peer
+	cpeer *clientPeer
+	speer *serverPeer
 
 	net p2p.MsgReadWriter // Network layer reader/writer to simulate remote messaging
 	app *p2p.MsgPipeRW    // Application layer reader/writer to simulate the local side
@@ -308,7 +309,7 @@ func newTestPeer(t *testing.T, name string, version int, handler *serverHandler,
 	// Generate a random id and create the peer
 	var id enode.ID
 	rand.Read(id[:])
-	peer := newPeer(version, NetworkId, false, p2p.NewPeer(id, name, nil), net)
+	peer := newClientPeer(version, NetworkId, p2p.NewPeer(id, name, nil), net)
 
 	// Start the peer on a new thread
 	errCh := make(chan error, 1)
@@ -320,9 +321,9 @@ func newTestPeer(t *testing.T, name string, version int, handler *serverHandler,
 		}
 	}()
 	tp := &testPeer{
-		app:  app,
-		net:  net,
-		peer: peer,
+		app:   app,
+		net:   net,
+		cpeer: peer,
 	}
 	// Execute any implicitly requested handshakes and return
 	if shake {
@@ -354,8 +355,8 @@ func newTestPeerPair(name string, version int, server *serverHandler, client *cl
 	var id enode.ID
 	rand.Read(id[:])
 
-	peer1 := newPeer(version, NetworkId, false, p2p.NewPeer(id, name, nil), net)
-	peer2 := newPeer(version, NetworkId, false, p2p.NewPeer(id, name, nil), app)
+	peer1 := newClientPeer(version, NetworkId, p2p.NewPeer(id, name, nil), net)
+	peer2 := newServerPeer(version, NetworkId, false, p2p.NewPeer(id, name, nil), app)
 
 	// Start the peer on a new thread
 	errc1 := make(chan error, 1)
@@ -374,14 +375,14 @@ func newTestPeerPair(name string, version int, server *serverHandler, client *cl
 		case errc1 <- client.handle(peer2):
 		}
 	}()
-	return &testPeer{peer: peer1, net: net, app: app}, errc1, &testPeer{peer: peer2, net: app, app: net}, errc2
+	return &testPeer{cpeer: peer1, net: net, app: app}, errc1, &testPeer{speer: peer2, net: app, app: net}, errc2
 }
 
 // handshake simulates a trivial handshake that expects the same state from the
 // remote side as we are simulating locally.
 func (p *testPeer) handshake(t *testing.T, td *big.Int, head common.Hash, headNum uint64, genesis common.Hash, costList RequestCostList) {
 	var expList keyValueList
-	expList = expList.add("protocolVersion", uint64(p.peer.version))
+	expList = expList.add("protocolVersion", uint64(p.cpeer.version))
 	expList = expList.add("networkId", uint64(NetworkId))
 	expList = expList.add("headTd", td)
 	expList = expList.add("headHash", head)
@@ -404,7 +405,7 @@ func (p *testPeer) handshake(t *testing.T, td *big.Int, head common.Hash, headNu
 	if err := p2p.Send(p.app, StatusMsg, sendList); err != nil {
 		t.Fatalf("status send: %v", err)
 	}
-	p.peer.fcParams = flowcontrol.ServerParams{
+	p.cpeer.fcParams = flowcontrol.ServerParams{
 		BufLimit:    testBufLimit,
 		MinRecharge: testBufRecharge,
 	}
@@ -445,7 +446,7 @@ func newServerEnv(t *testing.T, blocks int, protocol int, callback indexerCallba
 	if simClock {
 		clock = &mclock.Simulated{}
 	}
-	handler, b := newTestServerHandler(blocks, indexers, db, newPeerSet(), clock)
+	handler, b := newTestServerHandler(blocks, indexers, db, newClientPeerSet(), clock)
 
 	var peer *testPeer
 	if newPeer {
@@ -473,6 +474,7 @@ func newServerEnv(t *testing.T, blocks int, protocol int, callback indexerCallba
 	teardown := func() {
 		if newPeer {
 			peer.close()
+			peer.cpeer.close()
 			b.Close()
 		}
 		cIndexer.Close()
@@ -483,14 +485,14 @@ func newServerEnv(t *testing.T, blocks int, protocol int, callback indexerCallba
 
 func newClientServerEnv(t *testing.T, blocks int, protocol int, callback indexerCallback, ulcServers []string, ulcFraction int, simClock bool, connect bool) (*testServer, *testClient, func()) {
 	sdb, cdb := rawdb.NewMemoryDatabase(), rawdb.NewMemoryDatabase()
-	speers, cPeers := newPeerSet(), newPeerSet()
+	speers, cpeers := newServerPeerSet(), newClientPeerSet()
 
 	var clock mclock.Clock = &mclock.System{}
 	if simClock {
 		clock = &mclock.Simulated{}
 	}
-	dist := newRequestDistributor(cPeers, clock)
-	rm := newRetrieveManager(cPeers, dist, nil)
+	dist := newRequestDistributor(speers, clock)
+	rm := newRetrieveManager(speers, dist, nil)
 	odr := NewLesOdr(cdb, light.TestClientIndexerConfig, rm)
 
 	sindexers := testIndexers(sdb, nil, light.TestServerIndexerConfig)
@@ -500,8 +502,8 @@ func newClientServerEnv(t *testing.T, blocks int, protocol int, callback indexer
 	ccIndexer, cbIndexer, cbtIndexer := cIndexers[0], cIndexers[1], cIndexers[2]
 	odr.SetIndexers(ccIndexer, cbIndexer, cbtIndexer)
 
-	server, b := newTestServerHandler(blocks, sindexers, sdb, speers, clock)
-	client := newTestClientHandler(b, odr, cIndexers, cdb, cPeers, ulcServers, ulcFraction)
+	server, b := newTestServerHandler(blocks, sindexers, sdb, cpeers, clock)
+	client := newTestClientHandler(b, odr, cIndexers, cdb, speers, ulcServers, ulcFraction)
 
 	scIndexer.Start(server.blockchain)
 	sbIndexer.Start(server.blockchain)
@@ -548,6 +550,8 @@ func newClientServerEnv(t *testing.T, blocks int, protocol int, callback indexer
 		if connect {
 			speer.close()
 			cpeer.close()
+			cpeer.cpeer.close()
+			speer.speer.close()
 		}
 		ccIndexer.Close()
 		cbIndexer.Close()
diff --git a/les/txrelay.go b/les/txrelay.go
index d37a18faff..595c4d5808 100644
--- a/les/txrelay.go
+++ b/les/txrelay.go
@@ -27,14 +27,13 @@ import (
 
 type ltrInfo struct {
 	tx     *types.Transaction
-	sentTo map[*peer]struct{}
+	sentTo map[*serverPeer]struct{}
 }
 
 type lesTxRelay struct {
 	txSent       map[common.Hash]*ltrInfo
 	txPending    map[common.Hash]struct{}
-	ps           *peerSet
-	peerList     []*peer
+	peerList     []*serverPeer
 	peerStartPos int
 	lock         sync.RWMutex
 	stop         chan struct{}
@@ -42,15 +41,14 @@ type lesTxRelay struct {
 	retriever *retrieveManager
 }
 
-func newLesTxRelay(ps *peerSet, retriever *retrieveManager) *lesTxRelay {
+func newLesTxRelay(ps *serverPeerSet, retriever *retrieveManager) *lesTxRelay {
 	r := &lesTxRelay{
 		txSent:    make(map[common.Hash]*ltrInfo),
 		txPending: make(map[common.Hash]struct{}),
-		ps:        ps,
 		retriever: retriever,
 		stop:      make(chan struct{}),
 	}
-	ps.notify(r)
+	ps.subscribe(r)
 	return r
 }
 
@@ -58,24 +56,34 @@ func (ltrx *lesTxRelay) Stop() {
 	close(ltrx.stop)
 }
 
-func (ltrx *lesTxRelay) registerPeer(p *peer) {
+func (ltrx *lesTxRelay) registerPeer(p *serverPeer) {
 	ltrx.lock.Lock()
 	defer ltrx.lock.Unlock()
 
-	ltrx.peerList = ltrx.ps.AllPeers()
+	// Short circuit if the peer is announce only.
+	if p.onlyAnnounce {
+		return
+	}
+	ltrx.peerList = append(ltrx.peerList, p)
 }
 
-func (ltrx *lesTxRelay) unregisterPeer(p *peer) {
+func (ltrx *lesTxRelay) unregisterPeer(p *serverPeer) {
 	ltrx.lock.Lock()
 	defer ltrx.lock.Unlock()
 
-	ltrx.peerList = ltrx.ps.AllPeers()
+	for i, peer := range ltrx.peerList {
+		if peer == p {
+			// Remove from the peer list
+			ltrx.peerList = append(ltrx.peerList[:i], ltrx.peerList[i+1:]...)
+			return
+		}
+	}
 }
 
 // send sends a list of transactions to at most a given number of peers at
 // once, never resending any particular transaction to the same peer twice
 func (ltrx *lesTxRelay) send(txs types.Transactions, count int) {
-	sendTo := make(map[*peer]types.Transactions)
+	sendTo := make(map[*serverPeer]types.Transactions)
 
 	ltrx.peerStartPos++ // rotate the starting position of the peer list
 	if ltrx.peerStartPos >= len(ltrx.peerList) {
@@ -88,7 +96,7 @@ func (ltrx *lesTxRelay) send(txs types.Transactions, count int) {
 		if !ok {
 			ltr = &ltrInfo{
 				tx:     tx,
-				sentTo: make(map[*peer]struct{}),
+				sentTo: make(map[*serverPeer]struct{}),
 			}
 			ltrx.txSent[hash] = ltr
 			ltrx.txPending[hash] = struct{}{}
@@ -126,17 +134,17 @@ func (ltrx *lesTxRelay) send(txs types.Transactions, count int) {
 		reqID := genReqID()
 		rq := &distReq{
 			getCost: func(dp distPeer) uint64 {
-				peer := dp.(*peer)
-				return peer.GetTxRelayCost(len(ll), len(enc))
+				peer := dp.(*serverPeer)
+				return peer.getTxRelayCost(len(ll), len(enc))
 			},
 			canSend: func(dp distPeer) bool {
-				return !dp.(*peer).onlyAnnounce && dp.(*peer) == pp
+				return !dp.(*serverPeer).onlyAnnounce && dp.(*serverPeer) == pp
 			},
 			request: func(dp distPeer) func() {
-				peer := dp.(*peer)
-				cost := peer.GetTxRelayCost(len(ll), len(enc))
+				peer := dp.(*serverPeer)
+				cost := peer.getTxRelayCost(len(ll), len(enc))
 				peer.fcServer.QueuedRequest(reqID, cost)
-				return func() { peer.SendTxs(reqID, cost, enc) }
+				return func() { peer.sendTxs(reqID, enc) }
 			},
 		}
 		go ltrx.retriever.retrieve(context.Background(), reqID, rq, func(p distPeer, msg *Msg) error { return nil }, ltrx.stop)
diff --git a/les/ulc_test.go b/les/ulc_test.go
index 9112bf928c..273c63e4bd 100644
--- a/les/ulc_test.go
+++ b/les/ulc_test.go
@@ -54,14 +54,14 @@ func testULCAnnounceThreshold(t *testing.T, protocol int) {
 			ids       []string
 		)
 		for i := 0; i < len(testcase.height); i++ {
-			s, n, teardown := newServerPeer(t, 0, protocol)
+			s, n, teardown := newTestServerPeer(t, 0, protocol)
 
 			servers = append(servers, s)
 			nodes = append(nodes, n)
 			teardowns = append(teardowns, teardown)
 			ids = append(ids, n.String())
 		}
-		c, teardown := newLightPeer(t, protocol, ids, testcase.threshold)
+		c, teardown := newTestLightPeer(t, protocol, ids, testcase.threshold)
 
 		// Connect all servers.
 		for i := 0; i < len(servers); i++ {
@@ -86,15 +86,15 @@ func testULCAnnounceThreshold(t *testing.T, protocol int) {
 	}
 }
 
-func connect(server *serverHandler, serverId enode.ID, client *clientHandler, protocol int) (*peer, *peer, error) {
+func connect(server *serverHandler, serverId enode.ID, client *clientHandler, protocol int) (*serverPeer, *clientPeer, error) {
 	// Create a message pipe to communicate through
 	app, net := p2p.MsgPipe()
 
 	var id enode.ID
 	rand.Read(id[:])
 
-	peer1 := newPeer(protocol, NetworkId, true, p2p.NewPeer(serverId, "", nil), net) // Mark server as trusted
-	peer2 := newPeer(protocol, NetworkId, false, p2p.NewPeer(id, "", nil), app)
+	peer1 := newServerPeer(protocol, NetworkId, true, p2p.NewPeer(serverId, "", nil), net) // Mark server as trusted
+	peer2 := newClientPeer(protocol, NetworkId, p2p.NewPeer(id, "", nil), app)
 
 	// Start the peerLight on a new thread
 	errc1 := make(chan error, 1)
@@ -124,8 +124,8 @@ func connect(server *serverHandler, serverId enode.ID, client *clientHandler, pr
 	return peer1, peer2, nil
 }
 
-// newServerPeer creates server peer.
-func newServerPeer(t *testing.T, blocks int, protocol int) (*testServer, *enode.Node, func()) {
+// newTestServerPeer creates server peer.
+func newTestServerPeer(t *testing.T, blocks int, protocol int) (*testServer, *enode.Node, func()) {
 	s, teardown := newServerEnv(t, blocks, protocol, nil, false, false, 0)
 	key, err := crypto.GenerateKey()
 	if err != nil {
@@ -136,8 +136,8 @@ func newServerPeer(t *testing.T, blocks int, protocol int) (*testServer, *enode.
 	return s, n, teardown
 }
 
-// newLightPeer creates node with light sync mode
-func newLightPeer(t *testing.T, protocol int, ulcServers []string, ulcFraction int) (*testClient, func()) {
+// newTestLightPeer creates node with light sync mode
+func newTestLightPeer(t *testing.T, protocol int, ulcServers []string, ulcFraction int) (*testClient, func()) {
 	_, c, teardown := newClientServerEnv(t, 0, protocol, nil, ulcServers, ulcFraction, false, false)
 	return c, teardown
 }