Merge pull request #1351 from karalabe/eth61

Implement eth/61

13 files changed, 981 insertions, 306 deletions

diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index 645f51b9a..be40d5137 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -277,7 +277,6 @@ JavaScript API. See https://github.com/ethereum/go-ethereum/wiki/Javascipt-Conso
 		utils.ExecFlag,
 		utils.WhisperEnabledFlag,
 		utils.VMDebugFlag,
-		utils.ProtocolVersionFlag,
 		utils.NetworkIdFlag,
 		utils.RPCCORSDomainFlag,
 		utils.VerbosityFlag,
@@ -644,7 +643,7 @@ func version(c *cli.Context) {
 	if gitCommit != "" {
 		fmt.Println("Git Commit:", gitCommit)
 	}
-	fmt.Println("Protocol Version:", c.GlobalInt(utils.ProtocolVersionFlag.Name))
+	fmt.Println("Protocol Versions:", eth.ProtocolVersions)
 	fmt.Println("Network Id:", c.GlobalInt(utils.NetworkIdFlag.Name))
 	fmt.Println("Go Version:", runtime.Version())
 	fmt.Println("OS:", runtime.GOOS)
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 0d59980ec..6f319eb40 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -82,11 +82,6 @@ var (
 		Usage: "Data directory to be used",
 		Value: DirectoryString{common.DefaultDataDir()},
 	}
-	ProtocolVersionFlag = cli.IntFlag{
-		Name:  "protocolversion",
-		Usage: "ETH protocol version (integer)",
-		Value: eth.ProtocolVersion,
-	}
 	NetworkIdFlag = cli.IntFlag{
 		Name:  "networkid",
 		Usage: "Network Id (integer)",
@@ -359,7 +354,6 @@ func MakeEthConfig(clientID, version string, ctx *cli.Context) *eth.Config {
 	return &eth.Config{
 		Name:                    common.MakeName(clientID, version),
 		DataDir:                 ctx.GlobalString(DataDirFlag.Name),
-		ProtocolVersion:         ctx.GlobalInt(ProtocolVersionFlag.Name),
 		GenesisNonce:            ctx.GlobalInt(GenesisNonceFlag.Name),
 		BlockChainVersion:       ctx.GlobalInt(BlockchainVersionFlag.Name),
 		SkipBcVersionCheck:      false,
diff --git a/eth/backend.go b/eth/backend.go
index 4644b8a93..d6ad3381d 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -11,8 +11,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/ethereum/go-ethereum/metrics"
-
 	"github.com/ethereum/ethash"
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
@@ -26,6 +24,7 @@ import (
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/miner"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discover"
@@ -57,10 +56,9 @@ var (
 )
 
 type Config struct {
-	Name            string
-	ProtocolVersion int
-	NetworkId       int
-	GenesisNonce    int
+	Name         string
+	NetworkId    int
+	GenesisNonce int
 
 	BlockChainVersion  int
 	SkipBcVersionCheck bool // e.g. blockchain export
@@ -226,7 +224,6 @@ type Ethereum struct {
 	autodagquit   chan bool
 	etherbase     common.Address
 	clientVersion string
-	ethVersionId  int
 	netVersionId  int
 	shhVersionId  int
 }
@@ -291,14 +288,20 @@ func New(config *Config) (*Ethereum, error) {
 	nodeDb := filepath.Join(config.DataDir, "nodes")
 
 	// Perform database sanity checks
-	d, _ := blockDb.Get([]byte("ProtocolVersion"))
-	protov := int(common.NewValue(d).Uint())
-	if protov != config.ProtocolVersion && protov != 0 {
-		path := filepath.Join(config.DataDir, "blockchain")
-		return nil, fmt.Errorf("Database version mismatch. Protocol(%d / %d). `rm -rf %s`", protov, config.ProtocolVersion, path)
-	}
-	saveProtocolVersion(blockDb, config.ProtocolVersion)
-	glog.V(logger.Info).Infof("Protocol Version: %v, Network Id: %v", config.ProtocolVersion, config.NetworkId)
+	/*
+		// The databases were previously tied to protocol versions. Currently we
+		// are moving away from this decision as approaching Frontier. The below
+		// check was left in for now but should eventually be just dropped.
+
+		d, _ := blockDb.Get([]byte("ProtocolVersion"))
+		protov := int(common.NewValue(d).Uint())
+		if protov != config.ProtocolVersion && protov != 0 {
+			path := filepath.Join(config.DataDir, "blockchain")
+			return nil, fmt.Errorf("Database version mismatch. Protocol(%d / %d). `rm -rf %s`", protov, config.ProtocolVersion, path)
+		}
+		saveProtocolVersion(blockDb, config.ProtocolVersion)
+	*/
+	glog.V(logger.Info).Infof("Protocol Versions: %v, Network Id: %v", ProtocolVersions, config.NetworkId)
 
 	if !config.SkipBcVersionCheck {
 		b, _ := blockDb.Get([]byte("BlockchainVersion"))
@@ -321,7 +324,6 @@ func New(config *Config) (*Ethereum, error) {
 		DataDir:                 config.DataDir,
 		etherbase:               common.HexToAddress(config.Etherbase),
 		clientVersion:           config.Name, // TODO should separate from Name
-		ethVersionId:            config.ProtocolVersion,
 		netVersionId:            config.NetworkId,
 		NatSpec:                 config.NatSpec,
 		MinerThreads:            config.MinerThreads,
@@ -345,7 +347,7 @@ func New(config *Config) (*Ethereum, error) {
 
 	eth.blockProcessor = core.NewBlockProcessor(stateDb, extraDb, eth.pow, eth.chainManager, eth.EventMux())
 	eth.chainManager.SetProcessor(eth.blockProcessor)
-	eth.protocolManager = NewProtocolManager(config.ProtocolVersion, config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.chainManager)
+	eth.protocolManager = NewProtocolManager(config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.chainManager)
 
 	eth.miner = miner.New(eth, eth.EventMux(), eth.pow)
 	eth.miner.SetGasPrice(config.GasPrice)
@@ -358,7 +360,7 @@ func New(config *Config) (*Ethereum, error) {
 	if err != nil {
 		return nil, err
 	}
-	protocols := []p2p.Protocol{eth.protocolManager.SubProtocol}
+	protocols := append([]p2p.Protocol{}, eth.protocolManager.SubProtocols...)
 	if config.Shh {
 		protocols = append(protocols, eth.whisper.Protocol())
 	}
@@ -495,7 +497,7 @@ func (s *Ethereum) PeerCount() int                       { return s.net.PeerCoun
 func (s *Ethereum) Peers() []*p2p.Peer                   { return s.net.Peers() }
 func (s *Ethereum) MaxPeers() int                        { return s.net.MaxPeers }
 func (s *Ethereum) ClientVersion() string                { return s.clientVersion }
-func (s *Ethereum) EthVersion() int                      { return s.ethVersionId }
+func (s *Ethereum) EthVersion() int                      { return int(s.protocolManager.SubProtocols[0].Version) }
 func (s *Ethereum) NetVersion() int                      { return s.netVersionId }
 func (s *Ethereum) ShhVersion() int                      { return s.shhVersionId }
 func (s *Ethereum) Downloader() *downloader.Downloader   { return s.protocolManager.downloader }
@@ -504,7 +506,7 @@ func (s *Ethereum) Downloader() *downloader.Downloader   { return s.protocolMana
 func (s *Ethereum) Start() error {
 	jsonlogger.LogJson(&logger.LogStarting{
 		ClientString:    s.net.Name,
-		ProtocolVersion: ProtocolVersion,
+		ProtocolVersion: s.EthVersion(),
 	})
 	err := s.net.Start()
 	if err != nil {
@@ -560,7 +562,7 @@ done:
 func (s *Ethereum) StartForTest() {
 	jsonlogger.LogJson(&logger.LogStarting{
 		ClientString:    s.net.Name,
-		ProtocolVersion: ProtocolVersion,
+		ProtocolVersion: s.EthVersion(),
 	})
 }
 
@@ -667,14 +669,20 @@ func (self *Ethereum) StopAutoDAG() {
 	glog.V(logger.Info).Infof("Automatic pregeneration of ethash DAG OFF (ethash dir: %s)", ethash.DefaultDir)
 }
 
-func saveProtocolVersion(db common.Database, protov int) {
-	d, _ := db.Get([]byte("ProtocolVersion"))
-	protocolVersion := common.NewValue(d).Uint()
+/*
+	// The databases were previously tied to protocol versions. Currently we
+	// are moving away from this decision as approaching Frontier. The below
+	// code was left in for now but should eventually be just dropped.
+
+	func saveProtocolVersion(db common.Database, protov int) {
+		d, _ := db.Get([]byte("ProtocolVersion"))
+		protocolVersion := common.NewValue(d).Uint()
 
-	if protocolVersion == 0 {
-		db.Put([]byte("ProtocolVersion"), common.NewValue(protov).Bytes())
+		if protocolVersion == 0 {
+			db.Put([]byte("ProtocolVersion"), common.NewValue(protov).Bytes())
+		}
 	}
-}
+*/
 
 func saveBlockchainVersion(db common.Database, bcVersion int) {
 	d, _ := db.Get([]byte("BlockchainVersion"))
diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index 39976aae1..c788048e9 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -19,18 +19,24 @@ import (
 	"gopkg.in/fatih/set.v0"
 )
 
+const (
+	eth60 = 60 // Constant to check for old protocol support
+	eth61 = 61 // Constant to check for new protocol support
+)
+
 var (
-	MinHashFetch  = 512  // Minimum amount of hashes to not consider a peer stalling
-	MaxHashFetch  = 2048 // Amount of hashes to be fetched per retrieval request
-	MaxBlockFetch = 128  // Amount of blocks to be fetched per retrieval request
+	MinHashFetch  = 512 // Minimum amount of hashes to not consider a peer stalling
+	MaxHashFetch  = 512 // Amount of hashes to be fetched per retrieval request
+	MaxBlockFetch = 128 // Amount of blocks to be fetched per retrieval request
 
 	hashTTL         = 5 * time.Second  // Time it takes for a hash request to time out
 	blockSoftTTL    = 3 * time.Second  // Request completion threshold for increasing or decreasing a peer's bandwidth
 	blockHardTTL    = 3 * blockSoftTTL // Maximum time allowance before a block request is considered expired
 	crossCheckCycle = time.Second      // Period after which to check for expired cross checks
 
-	maxBannedHashes = 4096 // Number of bannable hashes before phasing old ones out
-	maxBlockProcess = 256  // Number of blocks to import at once into the chain
+	maxQueuedHashes = 256 * 1024 // Maximum number of hashes to queue for import (DOS protection)
+	maxBannedHashes = 4096       // Number of bannable hashes before phasing old ones out
+	maxBlockProcess = 256        // Number of blocks to import at once into the chain
 )
 
 var (
@@ -58,6 +64,9 @@ type hashCheckFn func(common.Hash) bool
 // blockRetrievalFn is a callback type for retrieving a block from the local chain.
 type blockRetrievalFn func(common.Hash) *types.Block
 
+// headRetrievalFn is a callback type for retrieving the head block from the local chain.
+type headRetrievalFn func() *types.Block
+
 // chainInsertFn is a callback type to insert a batch of blocks into the local chain.
 type chainInsertFn func(types.Blocks) (int, error)
 
@@ -98,6 +107,7 @@ type Downloader struct {
 	// Callbacks
 	hasBlock    hashCheckFn      // Checks if a block is present in the chain
 	getBlock    blockRetrievalFn // Retrieves a block from the chain
+	headBlock   headRetrievalFn  // Retrieves the head block from the chain
 	insertChain chainInsertFn    // Injects a batch of blocks into the chain
 	dropPeer    peerDropFn       // Drops a peer for misbehaving
 
@@ -109,8 +119,9 @@ type Downloader struct {
 
 	// Channels
 	newPeerCh chan *peer
-	hashCh    chan hashPack
-	blockCh   chan blockPack
+	hashCh    chan hashPack  // Channel receiving inbound hashes
+	blockCh   chan blockPack // Channel receiving inbound blocks
+	processCh chan bool      // Channel to signal the block fetcher of new or finished work
 
 	cancelCh   chan struct{} // Channel to cancel mid-flight syncs
 	cancelLock sync.RWMutex  // Lock to protect the cancel channel in delivers
@@ -123,7 +134,7 @@ type Block struct {
 }
 
 // New creates a new downloader to fetch hashes and blocks from remote peers.
-func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock blockRetrievalFn, insertChain chainInsertFn, dropPeer peerDropFn) *Downloader {
+func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock blockRetrievalFn, headBlock headRetrievalFn, insertChain chainInsertFn, dropPeer peerDropFn) *Downloader {
 	// Create the base downloader
 	downloader := &Downloader{
 		mux:         mux,
@@ -131,11 +142,13 @@ func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock blockRetrievalFn, in
 		peers:       newPeerSet(),
 		hasBlock:    hasBlock,
 		getBlock:    getBlock,
+		headBlock:   headBlock,
 		insertChain: insertChain,
 		dropPeer:    dropPeer,
 		newPeerCh:   make(chan *peer, 1),
 		hashCh:      make(chan hashPack, 1),
 		blockCh:     make(chan blockPack, 1),
+		processCh:   make(chan bool, 1),
 	}
 	// Inject all the known bad hashes
 	downloader.banned = set.New()
@@ -175,7 +188,7 @@ func (d *Downloader) Synchronising() bool {
 
 // RegisterPeer injects a new download peer into the set of block source to be
 // used for fetching hashes and blocks from.
-func (d *Downloader) RegisterPeer(id string, head common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) error {
+func (d *Downloader) RegisterPeer(id string, version int, head common.Hash, getRelHashes relativeHashFetcherFn, getAbsHashes absoluteHashFetcherFn, getBlocks blockFetcherFn) error {
 	// If the peer wants to send a banned hash, reject
 	if d.banned.Has(head) {
 		glog.V(logger.Debug).Infoln("Register rejected, head hash banned:", id)
@@ -183,7 +196,7 @@ func (d *Downloader) RegisterPeer(id string, head common.Hash, getHashes hashFet
 	}
 	// Otherwise try to construct and register the peer
 	glog.V(logger.Detail).Infoln("Registering peer", id)
-	if err := d.peers.Register(newPeer(id, head, getHashes, getBlocks)); err != nil {
+	if err := d.peers.Register(newPeer(id, version, head, getRelHashes, getAbsHashes, getBlocks)); err != nil {
 		glog.V(logger.Error).Infoln("Register failed:", err)
 		return err
 	}
@@ -289,12 +302,38 @@ func (d *Downloader) syncWithPeer(p *peer, hash common.Hash) (err error) {
 		}
 	}()
 
-	glog.V(logger.Debug).Infoln("Synchronizing with the network using:", p.id)
-	if err = d.fetchHashes(p, hash); err != nil {
-		return err
-	}
-	if err = d.fetchBlocks(); err != nil {
-		return err
+	glog.V(logger.Debug).Infof("Synchronizing with the network using: %s, eth/%d", p.id, p.version)
+	switch p.version {
+	case eth60:
+		// Old eth/60 version, use reverse hash retrieval algorithm
+		if err = d.fetchHashes60(p, hash); err != nil {
+			return err
+		}
+		if err = d.fetchBlocks60(); err != nil {
+			return err
+		}
+	case eth61:
+		// New eth/61, use forward, concurrent hash and block retrieval algorithm
+		number, err := d.findAncestor(p)
+		if err != nil {
+			return err
+		}
+		errc := make(chan error, 2)
+		go func() { errc <- d.fetchHashes(p, number+1) }()
+		go func() { errc <- d.fetchBlocks(number + 1) }()
+
+		// If any fetcher fails, cancel the other
+		if err := <-errc; err != nil {
+			d.cancel()
+			<-errc
+			return err
+		}
+		return <-errc
+
+	default:
+		// Something very wrong, stop right here
+		glog.V(logger.Error).Infof("Unsupported eth protocol: %d", p.version)
+		return errBadPeer
 	}
 	glog.V(logger.Debug).Infoln("Synchronization completed")
 
@@ -326,10 +365,10 @@ func (d *Downloader) Terminate() {
 	d.cancel()
 }
 
-// fetchHahes starts retrieving hashes backwards from a specific peer and hash,
+// fetchHashes60 starts retrieving hashes backwards from a specific peer and hash,
 // up until it finds a common ancestor. If the source peer times out, alternative
 // ones are tried for continuation.
-func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
+func (d *Downloader) fetchHashes60(p *peer, h common.Hash) error {
 	var (
 		start  = time.Now()
 		active = p             // active peer will help determine the current active peer
@@ -346,12 +385,12 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 	<-timeout.C // timeout channel should be initially empty.
 
 	getHashes := func(from common.Hash) {
-		go active.getHashes(from)
+		go active.getRelHashes(from)
 		timeout.Reset(hashTTL)
 	}
 
 	// Add the hash to the queue, and start hash retrieval.
-	d.queue.Insert([]common.Hash{h})
+	d.queue.Insert([]common.Hash{h}, false)
 	getHashes(h)
 
 	attempted[p.id] = true
@@ -377,7 +416,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 				if d.banned.Has(hash) {
 					glog.V(logger.Debug).Infof("Peer (%s) sent a known invalid chain", active.id)
 
-					d.queue.Insert(hashPack.hashes[:index+1])
+					d.queue.Insert(hashPack.hashes[:index+1], false)
 					if err := d.banBlocks(active.id, hash); err != nil {
 						glog.V(logger.Debug).Infof("Failed to ban batch of blocks: %v", err)
 					}
@@ -395,7 +434,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 				}
 			}
 			// Insert all the new hashes, but only continue if got something useful
-			inserts := d.queue.Insert(hashPack.hashes)
+			inserts := d.queue.Insert(hashPack.hashes, false)
 			if len(inserts) == 0 && !done {
 				glog.V(logger.Debug).Infof("Peer (%s) responded with stale hashes", active.id)
 				return errBadPeer
@@ -422,9 +461,9 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 				continue
 			}
 			// We're done, prepare the download cache and proceed pulling the blocks
-			offset := 0
+			offset := uint64(0)
 			if block := d.getBlock(head); block != nil {
-				offset = int(block.NumberU64() + 1)
+				offset = block.NumberU64() + 1
 			}
 			d.queue.Prepare(offset)
 			finished = true
@@ -481,10 +520,10 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
 	return nil
 }
 
-// fetchBlocks iteratively downloads the entire schedules block-chain, taking
+// fetchBlocks60 iteratively downloads the entire schedules block-chain, taking
 // any available peers, reserving a chunk of blocks for each, wait for delivery
 // and periodically checking for timeouts.
-func (d *Downloader) fetchBlocks() error {
+func (d *Downloader) fetchBlocks60() error {
 	glog.V(logger.Debug).Infoln("Downloading", d.queue.Pending(), "block(s)")
 	start := time.Now()
 
@@ -619,6 +658,332 @@ out:
 	return nil
 }
 
+// findAncestor tries to locate the common ancestor block of the local chain and
+// a remote peers blockchain. In the general case when our node was in sync and
+// on the correct chain, checking the top N blocks should already get us a match.
+// In the rare scenario when we ended up on a long soft fork (i.e. none of the
+// head blocks match), we do a binary search to find the common ancestor.
+func (d *Downloader) findAncestor(p *peer) (uint64, error) {
+	glog.V(logger.Debug).Infof("%v: looking for common ancestor", p)
+
+	// Request out head blocks to short circuit ancestor location
+	head := d.headBlock().NumberU64()
+	from := int64(head) - int64(MaxHashFetch)
+	if from < 0 {
+		from = 0
+	}
+	go p.getAbsHashes(uint64(from), MaxHashFetch)
+
+	// Wait for the remote response to the head fetch
+	number, hash := uint64(0), common.Hash{}
+	timeout := time.After(hashTTL)
+
+	for finished := false; !finished; {
+		select {
+		case <-d.cancelCh:
+			return 0, errCancelHashFetch
+
+		case hashPack := <-d.hashCh:
+			// Discard anything not from the origin peer
+			if hashPack.peerId != p.id {
+				glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", hashPack.peerId)
+				break
+			}
+			// Make sure the peer actually gave something valid
+			hashes := hashPack.hashes
+			if len(hashes) == 0 {
+				glog.V(logger.Debug).Infof("%v: empty head hash set", p)
+				return 0, errEmptyHashSet
+			}
+			// Check if a common ancestor was found
+			finished = true
+			for i := len(hashes) - 1; i >= 0; i-- {
+				if d.hasBlock(hashes[i]) {
+					number, hash = uint64(from)+uint64(i), hashes[i]
+					break
+				}
+			}
+
+		case <-d.blockCh:
+			// Out of bounds blocks received, ignore them
+
+		case <-timeout:
+			glog.V(logger.Debug).Infof("%v: head hash timeout", p)
+			return 0, errTimeout
+		}
+	}
+	// If the head fetch already found an ancestor, return
+	if !common.EmptyHash(hash) {
+		glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x]", p, number, hash[:4])
+		return number, nil
+	}
+	// Ancestor not found, we need to binary search over our chain
+	start, end := uint64(0), head
+	for start+1 < end {
+		// Split our chain interval in two, and request the hash to cross check
+		check := (start + end) / 2
+
+		timeout := time.After(hashTTL)
+		go p.getAbsHashes(uint64(check), 1)
+
+		// Wait until a reply arrives to this request
+		for arrived := false; !arrived; {
+			select {
+			case <-d.cancelCh:
+				return 0, errCancelHashFetch
+
+			case hashPack := <-d.hashCh:
+				// Discard anything not from the origin peer
+				if hashPack.peerId != p.id {
+					glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", hashPack.peerId)
+					break
+				}
+				// Make sure the peer actually gave something valid
+				hashes := hashPack.hashes
+				if len(hashes) != 1 {
+					glog.V(logger.Debug).Infof("%v: invalid search hash set (%d)", p, len(hashes))
+					return 0, errBadPeer
+				}
+				arrived = true
+
+				// Modify the search interval based on the response
+				block := d.getBlock(hashes[0])
+				if block == nil {
+					end = check
+					break
+				}
+				if block.NumberU64() != check {
+					glog.V(logger.Debug).Infof("%v: non requested hash #%d [%x], instead of #%d", p, block.NumberU64(), block.Hash().Bytes()[:4], check)
+					return 0, errBadPeer
+				}
+				start = check
+
+			case <-d.blockCh:
+				// Out of bounds blocks received, ignore them
+
+			case <-timeout:
+				glog.V(logger.Debug).Infof("%v: search hash timeout", p)
+				return 0, errTimeout
+			}
+		}
+	}
+	return start, nil
+}
+
+// fetchHashes keeps retrieving hashes from the requested number, until no more
+// are returned, potentially throttling on the way.
+func (d *Downloader) fetchHashes(p *peer, from uint64) error {
+	glog.V(logger.Debug).Infof("%v: downloading hashes from #%d", p, from)
+
+	// Create a timeout timer, and the associated hash fetcher
+	timeout := time.NewTimer(0) // timer to dump a non-responsive active peer
+	<-timeout.C                 // timeout channel should be initially empty
+	defer timeout.Stop()
+
+	getHashes := func(from uint64) {
+		glog.V(logger.Detail).Infof("%v: fetching %d hashes from #%d", p, MaxHashFetch, from)
+
+		go p.getAbsHashes(from, MaxHashFetch)
+		timeout.Reset(hashTTL)
+	}
+	// Start pulling hashes, until all are exhausted
+	getHashes(from)
+	for {
+		select {
+		case <-d.cancelCh:
+			return errCancelHashFetch
+
+		case hashPack := <-d.hashCh:
+			// Make sure the active peer is giving us the hashes
+			if hashPack.peerId != p.id {
+				glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", hashPack.peerId)
+				break
+			}
+			timeout.Stop()
+
+			// If no more hashes are inbound, notify the block fetcher and return
+			if len(hashPack.hashes) == 0 {
+				glog.V(logger.Debug).Infof("%v: no available hashes", p)
+
+				select {
+				case d.processCh <- false:
+				case <-d.cancelCh:
+				}
+				return nil
+			}
+			// Otherwise insert all the new hashes, aborting in case of junk
+			glog.V(logger.Detail).Infof("%v: inserting %d hashes from #%d", p, len(hashPack.hashes), from)
+
+			inserts := d.queue.Insert(hashPack.hashes, true)
+			if len(inserts) != len(hashPack.hashes) {
+				glog.V(logger.Debug).Infof("%v: stale hashes", p)
+				return errBadPeer
+			}
+			// Notify the block fetcher of new hashes, but stop if queue is full
+			cont := d.queue.Pending() < maxQueuedHashes
+			select {
+			case d.processCh <- cont:
+			default:
+			}
+			if !cont {
+				return nil
+			}
+			// Queue not yet full, fetch the next batch
+			from += uint64(len(hashPack.hashes))
+			getHashes(from)
+
+		case <-timeout.C:
+			glog.V(logger.Debug).Infof("%v: hash request timed out", p)
+			return errTimeout
+		}
+	}
+}
+
+// fetchBlocks iteratively downloads the scheduled hashes, taking any available
+// peers, reserving a chunk of blocks for each, waiting for delivery and also
+// periodically checking for timeouts.
+func (d *Downloader) fetchBlocks(from uint64) error {
+	glog.V(logger.Debug).Infof("Downloading blocks from #%d", from)
+	defer glog.V(logger.Debug).Infof("Block download terminated")
+
+	// Create a timeout timer for scheduling expiration tasks
+	ticker := time.NewTicker(100 * time.Millisecond)
+	defer ticker.Stop()
+
+	update := make(chan struct{}, 1)
+
+	// Prepare the queue and fetch blocks until the hash fetcher's done
+	d.queue.Prepare(from)
+	finished := false
+
+	for {
+		select {
+		case <-d.cancelCh:
+			return errCancelBlockFetch
+
+		case blockPack := <-d.blockCh:
+			// If the peer was previously banned and failed to deliver it's pack
+			// in a reasonable time frame, ignore it's message.
+			if peer := d.peers.Peer(blockPack.peerId); peer != nil {
+				// Deliver the received chunk of blocks, and demote in case of errors
+				err := d.queue.Deliver(blockPack.peerId, blockPack.blocks)
+				switch err {
+				case nil:
+					// If no blocks were delivered, demote the peer (need the delivery above)
+					if len(blockPack.blocks) == 0 {
+						peer.Demote()
+						peer.SetIdle()
+						glog.V(logger.Detail).Infof("%s: no blocks delivered", peer)
+						break
+					}
+					// All was successful, promote the peer and potentially start processing
+					peer.Promote()
+					peer.SetIdle()
+					glog.V(logger.Detail).Infof("%s: delivered %d blocks", peer, len(blockPack.blocks))
+					go d.process()
+
+				case errInvalidChain:
+					// The hash chain is invalid (blocks are not ordered properly), abort
+					return err
+
+				case errNoFetchesPending:
+					// Peer probably timed out with its delivery but came through
+					// in the end, demote, but allow to to pull from this peer.
+					peer.Demote()
+					peer.SetIdle()
+					glog.V(logger.Detail).Infof("%s: out of bound delivery", peer)
+
+				case errStaleDelivery:
+					// Delivered something completely else than requested, usually
+					// caused by a timeout and delivery during a new sync cycle.
+					// Don't set it to idle as the original request should still be
+					// in flight.
+					peer.Demote()
+					glog.V(logger.Detail).Infof("%s: stale delivery", peer)
+
+				default:
+					// Peer did something semi-useful, demote but keep it around
+					peer.Demote()
+					peer.SetIdle()
+					glog.V(logger.Detail).Infof("%s: delivery partially failed: %v", peer, err)
+					go d.process()
+				}
+			}
+			// Blocks arrived, try to update the progress
+			select {
+			case update <- struct{}{}:
+			default:
+			}
+
+		case cont := <-d.processCh:
+			// The hash fetcher sent a continuation flag, check if it's done
+			if !cont {
+				finished = true
+			}
+			// Hashes arrive, try to update the progress
+			select {
+			case update <- struct{}{}:
+			default:
+			}
+
+		case <-ticker.C:
+			// Sanity check update the progress
+			select {
+			case update <- struct{}{}:
+			default:
+			}
+
+		case <-update:
+			// Short circuit if we lost all our peers
+			if d.peers.Len() == 0 {
+				return errNoPeers
+			}
+			// Check for block request timeouts and demote the responsible peers
+			for _, pid := range d.queue.Expire(blockHardTTL) {
+				if peer := d.peers.Peer(pid); peer != nil {
+					peer.Demote()
+					glog.V(logger.Detail).Infof("%s: block delivery timeout", peer)
+				}
+			}
+			// If there's noting more to fetch, wait or terminate
+			if d.queue.Pending() == 0 {
+				if d.queue.InFlight() == 0 && finished {
+					glog.V(logger.Debug).Infof("Block fetching completed")
+					return nil
+				}
+				break
+			}
+			// Send a download request to all idle peers, until throttled
+			for _, peer := range d.peers.IdlePeers() {
+				// Short circuit if throttling activated
+				if d.queue.Throttle() {
+					break
+				}
+				// Reserve a chunk of hashes for a peer. A nil can mean either that
+				// no more hashes are available, or that the peer is known not to
+				// have them.
+				request := d.queue.Reserve(peer, peer.Capacity())
+				if request == nil {
+					continue
+				}
+				if glog.V(logger.Detail) {
+					glog.Infof("%s: requesting %d blocks", peer, len(request.Hashes))
+				}
+				// Fetch the chunk and make sure any errors return the hashes to the queue
+				if err := peer.Fetch(request); err != nil {
+					glog.V(logger.Error).Infof("%v: fetch failed, rescheduling", peer)
+					d.queue.Cancel(request)
+				}
+			}
+			// Make sure that we have peers available for fetching. If all peers have been tried
+			// and all failed throw an error
+			if !d.queue.Throttle() && d.queue.InFlight() == 0 {
+				return errPeersUnavailable
+			}
+		}
+	}
+}
+
 // banBlocks retrieves a batch of blocks from a peer feeding us invalid hashes,
 // and bans the head of the retrieved batch.
 //
diff --git a/eth/downloader/downloader_test.go b/eth/downloader/downloader_test.go
index 7feca8782..c5fb00289 100644
--- a/eth/downloader/downloader_test.go
+++ b/eth/downloader/downloader_test.go
@@ -21,7 +21,7 @@ var (
 	genesis   = core.GenesisBlockForTesting(testdb, common.Address{}, big.NewInt(0))
 )
 
-// makeChain creates a chain of n blocks starting at and including
+// makeChain creates a chain of n blocks starting at but not including
 // parent. the returned hash chain is ordered head->parent.
 func makeChain(n int, seed byte, parent *types.Block) ([]common.Hash, map[common.Hash]*types.Block) {
 	blocks := core.GenerateChain(parent, testdb, n, func(i int, gen *core.BlockGen) {
@@ -42,7 +42,7 @@ func makeChain(n int, seed byte, parent *types.Block) ([]common.Hash, map[common
 // h2[:f] are different but have a common suffix of length n-f.
 func makeChainFork(n, f int, parent *types.Block) (h1, h2 []common.Hash, b1, b2 map[common.Hash]*types.Block) {
 	// Create the common suffix.
-	h, b := makeChain(n-f-1, 0, parent)
+	h, b := makeChain(n-f, 0, parent)
 	// Create the forks.
 	h1, b1 = makeChain(f, 1, b[h[0]])
 	h1 = append(h1, h[1:]...)
@@ -75,7 +75,7 @@ func newTester() *downloadTester {
 		peerHashes: make(map[string][]common.Hash),
 		peerBlocks: make(map[string]map[common.Hash]*types.Block),
 	}
-	tester.downloader = New(new(event.TypeMux), tester.hasBlock, tester.getBlock, tester.insertChain, tester.dropPeer)
+	tester.downloader = New(new(event.TypeMux), tester.hasBlock, tester.getBlock, tester.headBlock, tester.insertChain, tester.dropPeer)
 
 	return tester
 }
@@ -99,6 +99,11 @@ func (dl *downloadTester) getBlock(hash common.Hash) *types.Block {
 	return dl.ownBlocks[hash]
 }
 
+// headBlock retrieves the current head block from the canonical chain.
+func (dl *downloadTester) headBlock() *types.Block {
+	return dl.getBlock(dl.ownHashes[len(dl.ownHashes)-1])
+}
+
 // insertChain injects a new batch of blocks into the simulated chain.
 func (dl *downloadTester) insertChain(blocks types.Blocks) (int, error) {
 	for i, block := range blocks {
@@ -112,15 +117,15 @@ func (dl *downloadTester) insertChain(blocks types.Blocks) (int, error) {
 }
 
 // newPeer registers a new block download source into the downloader.
-func (dl *downloadTester) newPeer(id string, hashes []common.Hash, blocks map[common.Hash]*types.Block) error {
-	return dl.newSlowPeer(id, hashes, blocks, 0)
+func (dl *downloadTester) newPeer(id string, version int, hashes []common.Hash, blocks map[common.Hash]*types.Block) error {
+	return dl.newSlowPeer(id, version, hashes, blocks, 0)
 }
 
 // newSlowPeer registers a new block download source into the downloader, with a
 // specific delay time on processing the network packets sent to it, simulating
 // potentially slow network IO.
-func (dl *downloadTester) newSlowPeer(id string, hashes []common.Hash, blocks map[common.Hash]*types.Block, delay time.Duration) error {
-	err := dl.downloader.RegisterPeer(id, hashes[0], dl.peerGetHashesFn(id, delay), dl.peerGetBlocksFn(id, delay))
+func (dl *downloadTester) newSlowPeer(id string, version int, hashes []common.Hash, blocks map[common.Hash]*types.Block, delay time.Duration) error {
+	err := dl.downloader.RegisterPeer(id, version, hashes[0], dl.peerGetRelHashesFn(id, delay), dl.peerGetAbsHashesFn(id, version, delay), dl.peerGetBlocksFn(id, delay))
 	if err == nil {
 		// Assign the owned hashes and blocks to the peer (deep copy)
 		dl.peerHashes[id] = make([]common.Hash, len(hashes))
@@ -141,10 +146,10 @@ func (dl *downloadTester) dropPeer(id string) {
 	dl.downloader.UnregisterPeer(id)
 }
 
-// peerGetBlocksFn constructs a getHashes function associated with a particular
+// peerGetRelHashesFn constructs a GetHashes function associated with a specific
 // peer in the download tester. The returned function can be used to retrieve
 // batches of hashes from the particularly requested peer.
-func (dl *downloadTester) peerGetHashesFn(id string, delay time.Duration) func(head common.Hash) error {
+func (dl *downloadTester) peerGetRelHashesFn(id string, delay time.Duration) func(head common.Hash) error {
 	return func(head common.Hash) error {
 		time.Sleep(delay)
 
@@ -174,13 +179,43 @@ func (dl *downloadTester) peerGetHashesFn(id string, delay time.Duration) func(h
 	}
 }
 
+// peerGetAbsHashesFn constructs a GetHashesFromNumber function associated with
+// a particular peer in the download tester. The returned function can be used to
+// retrieve batches of hashes from the particularly requested peer.
+func (dl *downloadTester) peerGetAbsHashesFn(id string, version int, delay time.Duration) func(uint64, int) error {
+	// If the simulated peer runs eth/60, this message is not supported
+	if version == eth60 {
+		return func(uint64, int) error { return nil }
+	}
+	// Otherwise create a method to request the blocks by number
+	return func(head uint64, count int) error {
+		time.Sleep(delay)
+
+		limit := count
+		if dl.maxHashFetch > 0 {
+			limit = dl.maxHashFetch
+		}
+		// Gather the next batch of hashes
+		hashes := dl.peerHashes[id]
+		result := make([]common.Hash, 0, limit)
+		for i := 0; i < limit && len(hashes)-int(head)-1-i >= 0; i++ {
+			result = append(result, hashes[len(hashes)-int(head)-1-i])
+		}
+		// Delay delivery a bit to allow attacks to unfold
+		go func() {
+			time.Sleep(time.Millisecond)
+			dl.downloader.DeliverHashes(id, result)
+		}()
+		return nil
+	}
+}
+
 // peerGetBlocksFn constructs a getBlocks function associated with a particular
 // peer in the download tester. The returned function can be used to retrieve
 // batches of blocks from the particularly requested peer.
 func (dl *downloadTester) peerGetBlocksFn(id string, delay time.Duration) func([]common.Hash) error {
 	return func(hashes []common.Hash) error {
 		time.Sleep(delay)
-
 		blocks := dl.peerBlocks[id]
 		result := make([]*types.Block, 0, len(hashes))
 		for _, hash := range hashes {
@@ -195,13 +230,13 @@ func (dl *downloadTester) peerGetBlocksFn(id string, delay time.Duration) func([
 }
 
 // Tests that simple synchronization, without throttling from a good peer works.
-func TestSynchronisation(t *testing.T) {
+func TestSynchronisation60(t *testing.T) {
 	// Create a small enough block chain to download and the tester
 	targetBlocks := blockCacheLimit - 15
 	hashes, blocks := makeChain(targetBlocks, 0, genesis)
 
 	tester := newTester()
-	tester.newPeer("peer", hashes, blocks)
+	tester.newPeer("peer", eth60, hashes, blocks)
 
 	// Synchronise with the peer and make sure all blocks were retrieved
 	if err := tester.sync("peer"); err != nil {
@@ -212,42 +247,79 @@ func TestSynchronisation(t *testing.T) {
 	}
 }
 
-// Tests that an inactive downloader will not accept incoming hashes and blocks.
-func TestInactiveDownloader(t *testing.T) {
+// Tests that simple synchronization against a canonical chain works correctly.
+// In this test common ancestor lookup should be short circuited and not require
+// binary searching.
+func TestCanonicalSynchronisation(t *testing.T) {
+	// Create a small enough block chain to download
+	targetBlocks := blockCacheLimit - 15
+	hashes, blocks := makeChain(targetBlocks, 0, genesis)
+
 	tester := newTester()
+	tester.newPeer("peer", eth61, hashes, blocks)
 
-	// Check that neither hashes nor blocks are accepted
-	if err := tester.downloader.DeliverHashes("bad peer", []common.Hash{}); err != errNoSyncActive {
-		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
+	// Synchronise with the peer and make sure all blocks were retrieved
+	if err := tester.sync("peer"); err != nil {
+		t.Fatalf("failed to synchronise blocks: %v", err)
 	}
-	if err := tester.downloader.DeliverBlocks("bad peer", []*types.Block{}); err != errNoSyncActive {
-		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
+	if imported := len(tester.ownBlocks); imported != targetBlocks+1 {
+		t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+1)
 	}
 }
 
-// Tests that a canceled download wipes all previously accumulated state.
-func TestCancel(t *testing.T) {
-	// Create a small enough block chain to download and the tester
-	targetBlocks := blockCacheLimit - 15
+// Tests that if a large batch of blocks are being downloaded, it is throttled
+// until the cached blocks are retrieved.
+func TestThrottling60(t *testing.T) {
+	// Create a long block chain to download and the tester
+	targetBlocks := 8 * blockCacheLimit
 	hashes, blocks := makeChain(targetBlocks, 0, genesis)
 
 	tester := newTester()
-	tester.newPeer("peer", hashes, blocks)
+	tester.newPeer("peer", eth60, hashes, blocks)
 
-	// Make sure canceling works with a pristine downloader
-	tester.downloader.cancel()
-	hashCount, blockCount := tester.downloader.queue.Size()
-	if hashCount > 0 || blockCount > 0 {
-		t.Errorf("block or hash count mismatch: %d hashes, %d blocks, want 0", hashCount, blockCount)
+	// Wrap the importer to allow stepping
+	done := make(chan int)
+	tester.downloader.insertChain = func(blocks types.Blocks) (int, error) {
+		n, err := tester.insertChain(blocks)
+		done <- n
+		return n, err
 	}
-	// Synchronise with the peer, but cancel afterwards
-	if err := tester.sync("peer"); err != nil {
-		t.Fatalf("failed to synchronise blocks: %v", err)
+	// Start a synchronisation concurrently
+	errc := make(chan error)
+	go func() {
+		errc <- tester.sync("peer")
+	}()
+	// Iteratively take some blocks, always checking the retrieval count
+	for len(tester.ownBlocks) < targetBlocks+1 {
+		// Wait a bit for sync to throttle itself
+		var cached int
+		for start := time.Now(); time.Since(start) < 3*time.Second; {
+			time.Sleep(25 * time.Millisecond)
+
+			cached = len(tester.downloader.queue.blockPool)
+			if cached == blockCacheLimit || len(tester.ownBlocks)+cached == targetBlocks+1 {
+				break
+			}
+		}
+		// Make sure we filled up the cache, then exhaust it
+		time.Sleep(25 * time.Millisecond) // give it a chance to screw up
+		if cached != blockCacheLimit && len(tester.ownBlocks)+cached < targetBlocks+1 {
+			t.Fatalf("block count mismatch: have %v, want %v", cached, blockCacheLimit)
+		}
+		<-done // finish previous blocking import
+		for cached > maxBlockProcess {
+			cached -= <-done
+		}
+		time.Sleep(25 * time.Millisecond) // yield to the insertion
 	}
-	tester.downloader.cancel()
-	hashCount, blockCount = tester.downloader.queue.Size()
-	if hashCount > 0 || blockCount > 0 {
-		t.Errorf("block or hash count mismatch: %d hashes, %d blocks, want 0", hashCount, blockCount)
+	<-done // finish the last blocking import
+
+	// Check that we haven't pulled more blocks than available
+	if len(tester.ownBlocks) > targetBlocks+1 {
+		t.Fatalf("target block count mismatch: have %v, want %v", len(tester.ownBlocks), targetBlocks+1)
+	}
+	if err := <-errc; err != nil {
+		t.Fatalf("block synchronization failed: %v", err)
 	}
 }
 
@@ -259,7 +331,7 @@ func TestThrottling(t *testing.T) {
 	hashes, blocks := makeChain(targetBlocks, 0, genesis)
 
 	tester := newTester()
-	tester.newPeer("peer", hashes, blocks)
+	tester.newPeer("peer", eth61, hashes, blocks)
 
 	// Wrap the importer to allow stepping
 	done := make(chan int)
@@ -307,6 +379,102 @@ func TestThrottling(t *testing.T) {
 	}
 }
 
+// Tests that simple synchronization against a forked chain works correctly. In
+// this test common ancestor lookup should *not* be short circuited, and a full
+// binary search should be executed.
+func TestForkedSynchronisation(t *testing.T) {
+	// Create a long enough forked chain
+	common, fork := MaxHashFetch, 2*MaxHashFetch
+	hashesA, hashesB, blocksA, blocksB := makeChainFork(common+fork, fork, genesis)
+
+	tester := newTester()
+	tester.newPeer("fork A", eth61, hashesA, blocksA)
+	tester.newPeer("fork B", eth61, hashesB, blocksB)
+
+	// Synchronise with the peer and make sure all blocks were retrieved
+	if err := tester.sync("fork A"); err != nil {
+		t.Fatalf("failed to synchronise blocks: %v", err)
+	}
+	if imported := len(tester.ownBlocks); imported != common+fork+1 {
+		t.Fatalf("synchronised block mismatch: have %v, want %v", imported, common+fork+1)
+	}
+	// Synchronise with the second peer and make sure that fork is pulled too
+	if err := tester.sync("fork B"); err != nil {
+		t.Fatalf("failed to synchronise blocks: %v", err)
+	}
+	if imported := len(tester.ownBlocks); imported != common+2*fork+1 {
+		t.Fatalf("synchronised block mismatch: have %v, want %v", imported, common+2*fork+1)
+	}
+}
+
+// Tests that an inactive downloader will not accept incoming hashes and blocks.
+func TestInactiveDownloader(t *testing.T) {
+	tester := newTester()
+
+	// Check that neither hashes nor blocks are accepted
+	if err := tester.downloader.DeliverHashes("bad peer", []common.Hash{}); err != errNoSyncActive {
+		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
+	}
+	if err := tester.downloader.DeliverBlocks("bad peer", []*types.Block{}); err != errNoSyncActive {
+		t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
+	}
+}
+
+// Tests that a canceled download wipes all previously accumulated state.
+func TestCancel60(t *testing.T) {
+	// Create a small enough block chain to download and the tester
+	targetBlocks := blockCacheLimit - 15
+	hashes, blocks := makeChain(targetBlocks, 0, genesis)
+
+	tester := newTester()
+	tester.newPeer("peer", eth60, hashes, blocks)
+
+	// Make sure canceling works with a pristine downloader
+	tester.downloader.cancel()
+	hashCount, blockCount := tester.downloader.queue.Size()
+	if hashCount > 0 || blockCount > 0 {
+		t.Errorf("block or hash count mismatch: %d hashes, %d blocks, want 0", hashCount, blockCount)
+	}
+	// Synchronise with the peer, but cancel afterwards
+	if err := tester.sync("peer"); err != nil {
+		t.Fatalf("failed to synchronise blocks: %v", err)
+	}
+	tester.downloader.cancel()
+	hashCount, blockCount = tester.downloader.queue.Size()
+	if hashCount > 0 || blockCount > 0 {
+		t.Errorf("block or hash count mismatch: %d hashes, %d blocks, want 0", hashCount, blockCount)
+	}
+}
+
+// Tests that a canceled download wipes all previously accumulated state.
+func TestCancel(t *testing.T) {
+	// Create a small enough block chain to download and the tester
+	targetBlocks := blockCacheLimit - 15
+	if targetBlocks >= MaxHashFetch {
+		targetBlocks = MaxHashFetch - 15
+	}
+	hashes, blocks := makeChain(targetBlocks, 0, genesis)
+
+	tester := newTester()
+	tester.newPeer("peer", eth61, hashes, blocks)
+
+	// Make sure canceling works with a pristine downloader
+	tester.downloader.cancel()
+	hashCount, blockCount := tester.downloader.queue.Size()
+	if hashCount > 0 || blockCount > 0 {
+		t.Errorf("block or hash count mismatch: %d hashes, %d blocks, want 0", hashCount, blockCount)
+	}
+	// Synchronise with the peer, but cancel afterwards
+	if err := tester.sync("peer"); err != nil {
+		t.Fatalf("failed to synchronise blocks: %v", err)
+	}
+	tester.downloader.cancel()
+	hashCount, blockCount = tester.downloader.queue.Size()
+	if hashCount > 0 || blockCount > 0 {
+		t.Errorf("block or hash count mismatch: %d hashes, %d blocks, want 0", hashCount, blockCount)
+	}
+}
+
 // Tests that synchronisation from multiple peers works as intended (multi thread sanity test).
 func TestMultiSynchronisation(t *testing.T) {
 	// Create various peers with various parts of the chain
@@ -317,7 +485,7 @@ func TestMultiSynchronisation(t *testing.T) {
 	tester := newTester()
 	for i := 0; i < targetPeers; i++ {
 		id := fmt.Sprintf("peer #%d", i)
-		tester.newPeer(id, hashes[i*blockCacheLimit:], blocks)
+		tester.newPeer(id, eth60, hashes[i*blockCacheLimit:], blocks)
 	}
 	// Synchronise with the middle peer and make sure half of the blocks were retrieved
 	id := fmt.Sprintf("peer #%d", targetPeers/2)
@@ -347,8 +515,8 @@ func TestSlowSynchronisation(t *testing.T) {
 	targetIODelay := time.Second
 	hashes, blocks := makeChain(targetBlocks, 0, genesis)
 
-	tester.newSlowPeer("fast", hashes, blocks, 0)
-	tester.newSlowPeer("slow", hashes, blocks, targetIODelay)
+	tester.newSlowPeer("fast", eth60, hashes, blocks, 0)
+	tester.newSlowPeer("slow", eth60, hashes, blocks, targetIODelay)
 
 	// Try to sync with the peers (pull hashes from fast)
 	start := time.Now()
@@ -370,13 +538,14 @@ func TestSlowSynchronisation(t *testing.T) {
 func TestNonExistingParentAttack(t *testing.T) {
 	tester := newTester()
 
+	// Forge a single-link chain with a forged header
 	hashes, blocks := makeChain(1, 0, genesis)
-	tester.newPeer("valid", hashes, blocks)
+	tester.newPeer("valid", eth60, hashes, blocks)
 
 	wrongblock := types.NewBlock(&types.Header{}, nil, nil, nil)
 	wrongblock.Td = blocks[hashes[0]].Td
 	hashes, blocks = makeChain(1, 0, wrongblock)
-	tester.newPeer("attack", hashes, blocks)
+	tester.newPeer("attack", eth60, hashes, blocks)
 
 	// Try and sync with the malicious node and check that it fails
 	if err := tester.sync("attack"); err == nil {
@@ -401,8 +570,8 @@ func TestRepeatingHashAttack(t *testing.T) { // TODO: Is this thing valid??
 
 	// Create a valid chain, but drop the last link
 	hashes, blocks := makeChain(blockCacheLimit, 0, genesis)
-	tester.newPeer("valid", hashes, blocks)
-	tester.newPeer("attack", hashes[:len(hashes)-1], blocks)
+	tester.newPeer("valid", eth60, hashes, blocks)
+	tester.newPeer("attack", eth60, hashes[:len(hashes)-1], blocks)
 
 	// Try and sync with the malicious node
 	errc := make(chan error)
@@ -431,10 +600,10 @@ func TestNonExistingBlockAttack(t *testing.T) {
 
 	// Create a valid chain, but forge the last link
 	hashes, blocks := makeChain(blockCacheLimit, 0, genesis)
-	tester.newPeer("valid", hashes, blocks)
+	tester.newPeer("valid", eth60, hashes, blocks)
 
 	hashes[len(hashes)/2] = common.Hash{}
-	tester.newPeer("attack", hashes, blocks)
+	tester.newPeer("attack", eth60, hashes, blocks)
 
 	// Try and sync with the malicious node and check that it fails
 	if err := tester.sync("attack"); err != errPeersUnavailable {
@@ -453,7 +622,7 @@ func TestInvalidHashOrderAttack(t *testing.T) {
 
 	// Create a valid long chain, but reverse some hashes within
 	hashes, blocks := makeChain(4*blockCacheLimit, 0, genesis)
-	tester.newPeer("valid", hashes, blocks)
+	tester.newPeer("valid", eth60, hashes, blocks)
 
 	chunk1 := make([]common.Hash, blockCacheLimit)
 	chunk2 := make([]common.Hash, blockCacheLimit)
@@ -462,7 +631,7 @@ func TestInvalidHashOrderAttack(t *testing.T) {
 
 	copy(hashes[2*blockCacheLimit:], chunk1)
 	copy(hashes[blockCacheLimit:], chunk2)
-	tester.newPeer("attack", hashes, blocks)
+	tester.newPeer("attack", eth60, hashes, blocks)
 
 	// Try and sync with the malicious node and check that it fails
 	if err := tester.sync("attack"); err != errInvalidChain {
@@ -489,8 +658,8 @@ func TestMadeupHashChainAttack(t *testing.T) {
 		rand.Read(randomHashes[i][:])
 	}
 
-	tester.newPeer("valid", hashes, blocks)
-	tester.newPeer("attack", randomHashes, nil)
+	tester.newPeer("valid", eth60, hashes, blocks)
+	tester.newPeer("attack", eth60, randomHashes, nil)
 
 	// Try and sync with the malicious node and check that it fails
 	if err := tester.sync("attack"); err != errCrossCheckFailed {
@@ -517,7 +686,7 @@ func TestMadeupHashChainDrippingAttack(t *testing.T) {
 
 	// Try and sync with the attacker, one hash at a time
 	tester.maxHashFetch = 1
-	tester.newPeer("attack", randomHashes, nil)
+	tester.newPeer("attack", eth60, randomHashes, nil)
 	if err := tester.sync("attack"); err != errStallingPeer {
 		t.Fatalf("synchronisation error mismatch: have %v, want %v", err, errStallingPeer)
 	}
@@ -540,7 +709,7 @@ func TestMadeupBlockChainAttack(t *testing.T) {
 	}
 	// Try and sync with the malicious node and check that it fails
 	tester := newTester()
-	tester.newPeer("attack", gapped, blocks)
+	tester.newPeer("attack", eth60, gapped, blocks)
 	if err := tester.sync("attack"); err != errCrossCheckFailed {
 		t.Fatalf("synchronisation error mismatch: have %v, want %v", err, errCrossCheckFailed)
 	}
@@ -548,13 +717,13 @@ func TestMadeupBlockChainAttack(t *testing.T) {
 	blockSoftTTL = defaultBlockTTL
 	crossCheckCycle = defaultCrossCheckCycle
 
-	tester.newPeer("valid", hashes, blocks)
+	tester.newPeer("valid", eth60, hashes, blocks)
 	if err := tester.sync("valid"); err != nil {
 		t.Fatalf("failed to synchronise blocks: %v", err)
 	}
 }
 
-// tests that if one/multiple malicious peers try to feed a banned blockchain to
+// Tests that if one/multiple malicious peers try to feed a banned blockchain to
 // the downloader, it will not keep refetching the same chain indefinitely, but
 // gradually block pieces of it, until its head is also blocked.
 func TestBannedChainStarvationAttack(t *testing.T) {
@@ -565,8 +734,8 @@ func TestBannedChainStarvationAttack(t *testing.T) {
 	// Create the tester and ban the selected hash.
 	tester := newTester()
 	tester.downloader.banned.Add(forkHashes[fork-1])
-	tester.newPeer("valid", hashes, blocks)
-	tester.newPeer("attack", forkHashes, forkBlocks)
+	tester.newPeer("valid", eth60, hashes, blocks)
+	tester.newPeer("attack", eth60, forkHashes, forkBlocks)
 
 	// Iteratively try to sync, and verify that the banned hash list grows until
 	// the head of the invalid chain is blocked too.
@@ -586,7 +755,7 @@ func TestBannedChainStarvationAttack(t *testing.T) {
 		banned = bans
 	}
 	// Check that after banning an entire chain, bad peers get dropped
-	if err := tester.newPeer("new attacker", forkHashes, forkBlocks); err != errBannedHead {
+	if err := tester.newPeer("new attacker", eth60, forkHashes, forkBlocks); err != errBannedHead {
 		t.Fatalf("peer registration mismatch: have %v, want %v", err, errBannedHead)
 	}
 	if peer := tester.downloader.peers.Peer("new attacker"); peer != nil {
@@ -618,8 +787,8 @@ func TestBannedChainMemoryExhaustionAttack(t *testing.T) {
 	MaxBlockFetch = 4
 	maxBannedHashes = 256
 
-	tester.newPeer("valid", hashes, blocks)
-	tester.newPeer("attack", forkHashes, forkBlocks)
+	tester.newPeer("valid", eth60, hashes, blocks)
+	tester.newPeer("attack", eth60, forkHashes, forkBlocks)
 
 	// Iteratively try to sync, and verify that the banned hash list grows until
 	// the head of the invalid chain is blocked too.
@@ -664,7 +833,7 @@ func TestOverlappingDeliveryAttack(t *testing.T) {
 
 	// Register an attacker that always returns non-requested blocks too
 	tester := newTester()
-	tester.newPeer("attack", hashes, blocks)
+	tester.newPeer("attack", eth60, hashes, blocks)
 
 	rawGetBlocks := tester.downloader.peers.Peer("attack").getBlocks
 	tester.downloader.peers.Peer("attack").getBlocks = func(request []common.Hash) error {
@@ -712,7 +881,7 @@ func TestHashAttackerDropping(t *testing.T) {
 	for i, tt := range tests {
 		// Register a new peer and ensure it's presence
 		id := fmt.Sprintf("test %d", i)
-		if err := tester.newPeer(id, []common.Hash{genesis.Hash()}, nil); err != nil {
+		if err := tester.newPeer(id, eth60, []common.Hash{genesis.Hash()}, nil); err != nil {
 			t.Fatalf("test %d: failed to register new peer: %v", i, err)
 		}
 		if _, ok := tester.peerHashes[id]; !ok {
@@ -744,7 +913,7 @@ func TestBlockAttackerDropping(t *testing.T) {
 	for i, tt := range tests {
 		// Register a new peer and ensure it's presence
 		id := fmt.Sprintf("test %d", i)
-		if err := tester.newPeer(id, []common.Hash{common.Hash{}}, nil); err != nil {
+		if err := tester.newPeer(id, eth60, []common.Hash{common.Hash{}}, nil); err != nil {
 			t.Fatalf("test %d: failed to register new peer: %v", i, err)
 		}
 		if _, ok := tester.peerHashes[id]; !ok {
diff --git a/eth/downloader/peer.go b/eth/downloader/peer.go
index f36e133e4..bd58b4dc8 100644
--- a/eth/downloader/peer.go
+++ b/eth/downloader/peer.go
@@ -15,7 +15,8 @@ import (
 	"gopkg.in/fatih/set.v0"
 )
 
-type hashFetcherFn func(common.Hash) error
+type relativeHashFetcherFn func(common.Hash) error
+type absoluteHashFetcherFn func(uint64, int) error
 type blockFetcherFn func([]common.Hash) error
 
 var (
@@ -37,20 +38,25 @@ type peer struct {
 
 	ignored *set.Set // Set of hashes not to request (didn't have previously)
 
-	getHashes hashFetcherFn  // Method to retrieve a batch of hashes (mockable for testing)
-	getBlocks blockFetcherFn // Method to retrieve a batch of blocks (mockable for testing)
+	getRelHashes relativeHashFetcherFn // Method to retrieve a batch of hashes from an origin hash
+	getAbsHashes absoluteHashFetcherFn // Method to retrieve a batch of hashes from an absolute position
+	getBlocks    blockFetcherFn        // Method to retrieve a batch of blocks
+
+	version int // Eth protocol version number to switch strategies
 }
 
 // newPeer create a new downloader peer, with specific hash and block retrieval
 // mechanisms.
-func newPeer(id string, head common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) *peer {
+func newPeer(id string, version int, head common.Hash, getRelHashes relativeHashFetcherFn, getAbsHashes absoluteHashFetcherFn, getBlocks blockFetcherFn) *peer {
 	return &peer{
-		id:        id,
-		head:      head,
-		capacity:  1,
-		getHashes: getHashes,
-		getBlocks: getBlocks,
-		ignored:   set.New(),
+		id:           id,
+		head:         head,
+		capacity:     1,
+		getRelHashes: getRelHashes,
+		getAbsHashes: getAbsHashes,
+		getBlocks:    getBlocks,
+		ignored:      set.New(),
+		version:      version,
 	}
 }
 
diff --git a/eth/downloader/queue.go b/eth/downloader/queue.go
index 903f043eb..b24ce42e8 100644
--- a/eth/downloader/queue.go
+++ b/eth/downloader/queue.go
@@ -40,9 +40,9 @@ type queue struct {
 
 	pendPool map[string]*fetchRequest // Currently pending block retrieval operations
 
-	blockPool   map[common.Hash]int // Hash-set of the downloaded data blocks, mapping to cache indexes
-	blockCache  []*Block            // Downloaded but not yet delivered blocks
-	blockOffset int                 // Offset of the first cached block in the block-chain
+	blockPool   map[common.Hash]uint64 // Hash-set of the downloaded data blocks, mapping to cache indexes
+	blockCache  []*Block               // Downloaded but not yet delivered blocks
+	blockOffset uint64                 // Offset of the first cached block in the block-chain
 
 	lock sync.RWMutex
 }
@@ -53,7 +53,7 @@ func newQueue() *queue {
 		hashPool:   make(map[common.Hash]int),
 		hashQueue:  prque.New(),
 		pendPool:   make(map[string]*fetchRequest),
-		blockPool:  make(map[common.Hash]int),
+		blockPool:  make(map[common.Hash]uint64),
 		blockCache: make([]*Block, blockCacheLimit),
 	}
 }
@@ -69,7 +69,7 @@ func (q *queue) Reset() {
 
 	q.pendPool = make(map[string]*fetchRequest)
 
-	q.blockPool = make(map[common.Hash]int)
+	q.blockPool = make(map[common.Hash]uint64)
 	q.blockOffset = 0
 	q.blockCache = make([]*Block, blockCacheLimit)
 }
@@ -130,7 +130,7 @@ func (q *queue) Has(hash common.Hash) bool {
 
 // Insert adds a set of hashes for the download queue for scheduling, returning
 // the new hashes encountered.
-func (q *queue) Insert(hashes []common.Hash) []common.Hash {
+func (q *queue) Insert(hashes []common.Hash, fifo bool) []common.Hash {
 	q.lock.Lock()
 	defer q.lock.Unlock()
 
@@ -147,7 +147,11 @@ func (q *queue) Insert(hashes []common.Hash) []common.Hash {
 		inserts = append(inserts, hash)
 
 		q.hashPool[hash] = q.hashCounter
-		q.hashQueue.Push(hash, float32(q.hashCounter)) // Highest gets schedules first
+		if fifo {
+			q.hashQueue.Push(hash, -float32(q.hashCounter)) // Lowest gets schedules first
+		} else {
+			q.hashQueue.Push(hash, float32(q.hashCounter)) // Highest gets schedules first
+		}
 	}
 	return inserts
 }
@@ -175,7 +179,7 @@ func (q *queue) GetBlock(hash common.Hash) *Block {
 		return nil
 	}
 	// Return the block if it's still available in the cache
-	if q.blockOffset <= index && index < q.blockOffset+len(q.blockCache) {
+	if q.blockOffset <= index && index < q.blockOffset+uint64(len(q.blockCache)) {
 		return q.blockCache[index-q.blockOffset]
 	}
 	return nil
@@ -202,7 +206,7 @@ func (q *queue) TakeBlocks() []*Block {
 	for k, n := len(q.blockCache)-len(blocks), len(q.blockCache); k < n; k++ {
 		q.blockCache[k] = nil
 	}
-	q.blockOffset += len(blocks)
+	q.blockOffset += uint64(len(blocks))
 
 	return blocks
 }
@@ -318,7 +322,7 @@ func (q *queue) Deliver(id string, blocks []*types.Block) (err error) {
 			continue
 		}
 		// If a requested block falls out of the range, the hash chain is invalid
-		index := int(block.NumberU64()) - q.blockOffset
+		index := int(int64(block.NumberU64()) - int64(q.blockOffset))
 		if index >= len(q.blockCache) || index < 0 {
 			return errInvalidChain
 		}
@@ -329,7 +333,7 @@ func (q *queue) Deliver(id string, blocks []*types.Block) (err error) {
 		}
 		delete(request.Hashes, hash)
 		delete(q.hashPool, hash)
-		q.blockPool[hash] = int(block.NumberU64())
+		q.blockPool[hash] = block.NumberU64()
 	}
 	// Return all failed or missing fetches to the queue
 	for hash, index := range request.Hashes {
@@ -346,7 +350,7 @@ func (q *queue) Deliver(id string, blocks []*types.Block) (err error) {
 }
 
 // Prepare configures the block cache offset to allow accepting inbound blocks.
-func (q *queue) Prepare(offset int) {
+func (q *queue) Prepare(offset uint64) {
 	q.lock.Lock()
 	defer q.lock.Unlock()
 
diff --git a/eth/handler.go b/eth/handler.go
index 278a2bec2..59bbb480b 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -49,7 +49,7 @@ type ProtocolManager struct {
 	fetcher        *fetcher.Fetcher
 	peers          *peerSet
 
-	SubProtocol p2p.Protocol
+	SubProtocols []p2p.Protocol
 
 	eventMux      *event.TypeMux
 	txSub         event.Subscription
@@ -68,8 +68,8 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
-func NewProtocolManager(protocolVersion, networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, chainman *core.ChainManager) *ProtocolManager {
-	// Create the protocol manager and initialize peer handlers
+func NewProtocolManager(networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, chainman *core.ChainManager) *ProtocolManager {
+	// Create the protocol manager with the base fields
 	manager := &ProtocolManager{
 		eventMux:  mux,
 		txpool:    txpool,
@@ -79,18 +79,24 @@ func NewProtocolManager(protocolVersion, networkId int, mux *event.TypeMux, txpo
 		txsyncCh:  make(chan *txsync),
 		quitSync:  make(chan struct{}),
 	}
-	manager.SubProtocol = p2p.Protocol{
-		Name:    "eth",
-		Version: uint(protocolVersion),
-		Length:  ProtocolLength,
-		Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
-			peer := manager.newPeer(protocolVersion, networkId, p, rw)
-			manager.newPeerCh <- peer
-			return manager.handle(peer)
-		},
+	// Initiate a sub-protocol for every implemented version we can handle
+	manager.SubProtocols = make([]p2p.Protocol, len(ProtocolVersions))
+	for i := 0; i < len(manager.SubProtocols); i++ {
+		version := ProtocolVersions[i]
+
+		manager.SubProtocols[i] = p2p.Protocol{
+			Name:    "eth",
+			Version: version,
+			Length:  ProtocolLengths[i],
+			Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
+				peer := manager.newPeer(int(version), networkId, p, rw)
+				manager.newPeerCh <- peer
+				return manager.handle(peer)
+			},
+		}
 	}
 	// Construct the different synchronisation mechanisms
-	manager.downloader = downloader.New(manager.eventMux, manager.chainman.HasBlock, manager.chainman.GetBlock, manager.chainman.InsertChain, manager.removePeer)
+	manager.downloader = downloader.New(manager.eventMux, manager.chainman.HasBlock, manager.chainman.GetBlock, manager.chainman.CurrentBlock, manager.chainman.InsertChain, manager.removePeer)
 
 	validator := func(block *types.Block, parent *types.Block) error {
 		return core.ValidateHeader(pow, block.Header(), parent, true)
@@ -152,31 +158,32 @@ func (pm *ProtocolManager) Stop() {
 }
 
 func (pm *ProtocolManager) newPeer(pv, nv int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
-	td, current, genesis := pm.chainman.Status()
-
-	return newPeer(pv, nv, genesis, current, td, p, rw)
+	return newPeer(pv, nv, p, rw)
 }
 
+// handle is the callback invoked to manage the life cycle of an eth peer. When
+// this function terminates, the peer is disconnected.
 func (pm *ProtocolManager) handle(p *peer) error {
-	// Execute the Ethereum handshake.
-	if err := p.handleStatus(); err != nil {
+	glog.V(logger.Debug).Infof("%v: peer connected [%s]", p, p.Name())
+
+	// Execute the Ethereum handshake
+	td, head, genesis := pm.chainman.Status()
+	if err := p.Handshake(td, head, genesis); err != nil {
+		glog.V(logger.Debug).Infof("%v: handshake failed: %v", p, err)
 		return err
 	}
-
-	// Register the peer locally.
-	glog.V(logger.Detail).Infoln("Adding peer", p.id)
+	// Register the peer locally
+	glog.V(logger.Detail).Infof("%v: adding peer", p)
 	if err := pm.peers.Register(p); err != nil {
-		glog.V(logger.Error).Infoln("Addition failed:", err)
+		glog.V(logger.Error).Infof("%v: addition failed: %v", p, err)
 		return err
 	}
 	defer pm.removePeer(p.id)
 
-	// Register the peer in the downloader. If the downloader
-	// considers it banned, we disconnect.
-	if err := pm.downloader.RegisterPeer(p.id, p.Head(), p.requestHashes, p.requestBlocks); err != nil {
+	// Register the peer in the downloader. If the downloader considers it banned, we disconnect
+	if err := pm.downloader.RegisterPeer(p.id, p.version, p.Head(), p.RequestHashes, p.RequestHashesFromNumber, p.RequestBlocks); err != nil {
 		return err
 	}
-
 	// Propagate existing transactions. new transactions appearing
 	// after this will be sent via broadcasts.
 	pm.syncTransactions(p)
@@ -184,13 +191,17 @@ func (pm *ProtocolManager) handle(p *peer) error {
 	// main loop. handle incoming messages.
 	for {
 		if err := pm.handleMsg(p); err != nil {
+			glog.V(logger.Debug).Infof("%v: message handling failed: %v", p, err)
 			return err
 		}
 	}
 	return nil
 }
 
+// handleMsg is invoked whenever an inbound message is received from a remote
+// peer. The remote connection is torn down upon returning any error.
 func (pm *ProtocolManager) handleMsg(p *peer) error {
+	// Read the next message from the remote peer, and ensure it's fully consumed
 	msg, err := p.rw.ReadMsg()
 	if err != nil {
 		return err
@@ -198,58 +209,69 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 	if msg.Size > ProtocolMaxMsgSize {
 		return errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
 	}
-	// make sure that the payload has been fully consumed
 	defer msg.Discard()
 
+	// Handle the message depending on its contents
 	switch msg.Code {
 	case StatusMsg:
+		// Status messages should never arrive after the handshake
 		return errResp(ErrExtraStatusMsg, "uncontrolled status message")
 
-	case TxMsg:
-		// TODO: rework using lazy RLP stream
-		var txs []*types.Transaction
-		if err := msg.Decode(&txs); err != nil {
-			return errResp(ErrDecode, "msg %v: %v", msg, err)
-		}
-		for i, tx := range txs {
-			if tx == nil {
-				return errResp(ErrDecode, "transaction %d is nil", i)
-			}
-			jsonlogger.LogJson(&logger.EthTxReceived{
-				TxHash:   tx.Hash().Hex(),
-				RemoteId: p.ID().String(),
-			})
-		}
-		pm.txpool.AddTransactions(txs)
-
 	case GetBlockHashesMsg:
-		var request getBlockHashesMsgData
+		// Retrieve the number of hashes to return and from which origin hash
+		var request getBlockHashesData
 		if err := msg.Decode(&request); err != nil {
-			return errResp(ErrDecode, "->msg %v: %v", msg, err)
+			return errResp(ErrDecode, "%v: %v", msg, err)
 		}
-
 		if request.Amount > uint64(downloader.MaxHashFetch) {
 			request.Amount = uint64(downloader.MaxHashFetch)
 		}
-
+		// Retrieve the hashes from the block chain and return them
 		hashes := pm.chainman.GetBlockHashesFromHash(request.Hash, request.Amount)
+		if len(hashes) == 0 {
+			glog.V(logger.Debug).Infof("invalid block hash %x", request.Hash.Bytes()[:4])
+		}
+		return p.SendBlockHashes(hashes)
 
-		if glog.V(logger.Debug) {
-			if len(hashes) == 0 {
-				glog.Infof("invalid block hash %x", request.Hash.Bytes()[:4])
-			}
+	case GetBlockHashesFromNumberMsg:
+		// Retrieve and decode the number of hashes to return and from which origin number
+		var request getBlockHashesFromNumberData
+		if err := msg.Decode(&request); err != nil {
+			return errResp(ErrDecode, "%v: %v", msg, err)
+		}
+		if request.Amount > uint64(downloader.MaxHashFetch) {
+			request.Amount = uint64(downloader.MaxHashFetch)
 		}
+		// Calculate the last block that should be retrieved, and short circuit if unavailable
+		last := pm.chainman.GetBlockByNumber(request.Number + request.Amount - 1)
+		if last == nil {
+			last = pm.chainman.CurrentBlock()
+			request.Amount = last.NumberU64() - request.Number + 1
+		}
+		if last.NumberU64() < request.Number {
+			return p.SendBlockHashes(nil)
+		}
+		// Retrieve the hashes from the last block backwards, reverse and return
+		hashes := []common.Hash{last.Hash()}
+		hashes = append(hashes, pm.chainman.GetBlockHashesFromHash(last.Hash(), request.Amount-1)...)
 
-		// returns either requested hashes or nothing (i.e. not found)
-		return p.sendBlockHashes(hashes)
+		for i := 0; i < len(hashes)/2; i++ {
+			hashes[i], hashes[len(hashes)-1-i] = hashes[len(hashes)-1-i], hashes[i]
+		}
+		return p.SendBlockHashes(hashes)
 
 	case BlockHashesMsg:
+		// A batch of hashes arrived to one of our previous requests
 		msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
+		reqHashInPacketsMeter.Mark(1)
 
 		var hashes []common.Hash
 		if err := msgStream.Decode(&hashes); err != nil {
 			break
 		}
+		reqHashInTrafficMeter.Mark(int64(32 * len(hashes)))
+
+		// Deliver them all to the downloader for queuing
 		err := pm.downloader.DeliverHashes(p.id, hashes)
 		if err != nil {
 			glog.V(logger.Debug).Infoln(err)
@@ -293,13 +315,14 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			}
 			list = list[:len(list)-2] + "]"
 
-			glog.Infof("Peer %s: no blocks found for requested hashes %s", p.id, list)
+			glog.Infof("%v: no blocks found for requested hashes %s", p, list)
 		}
-		return p.sendBlocks(blocks)
+		return p.SendBlocks(blocks)
 
 	case BlocksMsg:
 		// Decode the arrived block message
 		msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
+		reqBlockInPacketsMeter.Mark(1)
 
 		var blocks []*types.Block
 		if err := msgStream.Decode(&blocks); err != nil {
@@ -307,8 +330,9 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			blocks = nil
 		}
 		// Update the receive timestamp of each block
-		for i := 0; i < len(blocks); i++ {
-			blocks[i].ReceivedAt = msg.ReceivedAt
+		for _, block := range blocks {
+			reqBlockInTrafficMeter.Mark(block.Size().Int64())
+			block.ReceivedAt = msg.ReceivedAt
 		}
 		// Filter out any explicitly requested blocks, deliver the rest to the downloader
 		if blocks := pm.fetcher.Filter(blocks); len(blocks) > 0 {
@@ -323,9 +347,12 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 		if err := msgStream.Decode(&hashes); err != nil {
 			break
 		}
+		propHashInPacketsMeter.Mark(1)
+		propHashInTrafficMeter.Mark(int64(32 * len(hashes)))
+
 		// Mark the hashes as present at the remote node
 		for _, hash := range hashes {
-			p.blockHashes.Add(hash)
+			p.MarkBlock(hash)
 			p.SetHead(hash)
 		}
 		// Schedule all the unknown hashes for retrieval
@@ -336,15 +363,18 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			}
 		}
 		for _, hash := range unknown {
-			pm.fetcher.Notify(p.id, hash, time.Now(), p.requestBlocks)
+			pm.fetcher.Notify(p.id, hash, time.Now(), p.RequestBlocks)
 		}
 
 	case NewBlockMsg:
 		// Retrieve and decode the propagated block
-		var request newBlockMsgData
+		var request newBlockData
 		if err := msg.Decode(&request); err != nil {
 			return errResp(ErrDecode, "%v: %v", msg, err)
 		}
+		propBlockInPacketsMeter.Mark(1)
+		propBlockInTrafficMeter.Mark(request.Block.Size().Int64())
+
 		if err := request.Block.ValidateFields(); err != nil {
 			return errResp(ErrDecode, "block validation %v: %v", msg, err)
 		}
@@ -360,7 +390,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			RemoteId:      p.ID().String(),
 		})
 		// Mark the peer as owning the block and schedule it for import
-		p.blockHashes.Add(request.Block.Hash())
+		p.MarkBlock(request.Block.Hash())
 		p.SetHead(request.Block.Hash())
 
 		pm.fetcher.Enqueue(p.id, request.Block)
@@ -369,6 +399,29 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 		p.SetTd(request.TD)
 		go pm.synchronise(p)
 
+	case TxMsg:
+		// Transactions arrived, parse all of them and deliver to the pool
+		var txs []*types.Transaction
+		if err := msg.Decode(&txs); err != nil {
+			return errResp(ErrDecode, "msg %v: %v", msg, err)
+		}
+		propTxnInPacketsMeter.Mark(1)
+		for i, tx := range txs {
+			// Validate and mark the remote transaction
+			if tx == nil {
+				return errResp(ErrDecode, "transaction %d is nil", i)
+			}
+			p.MarkTransaction(tx.Hash())
+
+			// Log it's arrival for later analysis
+			propTxnInTrafficMeter.Mark(tx.Size().Int64())
+			jsonlogger.LogJson(&logger.EthTxReceived{
+				TxHash:   tx.Hash().Hex(),
+				RemoteId: p.ID().String(),
+			})
+		}
+		pm.txpool.AddTransactions(txs)
+
 	default:
 		return errResp(ErrInvalidMsgCode, "%v", msg.Code)
 	}
@@ -385,28 +438,27 @@ func (pm *ProtocolManager) BroadcastBlock(block *types.Block, propagate bool) {
 	if propagate {
 		transfer := peers[:int(math.Sqrt(float64(len(peers))))]
 		for _, peer := range transfer {
-			peer.sendNewBlock(block)
+			peer.SendNewBlock(block)
 		}
 		glog.V(logger.Detail).Infof("propagated block %x to %d peers in %v", hash[:4], len(transfer), time.Since(block.ReceivedAt))
 	}
 	// Otherwise if the block is indeed in out own chain, announce it
 	if pm.chainman.HasBlock(hash) {
 		for _, peer := range peers {
-			peer.sendNewBlockHashes([]common.Hash{hash})
+			peer.SendNewBlockHashes([]common.Hash{hash})
 		}
 		glog.V(logger.Detail).Infof("announced block %x to %d peers in %v", hash[:4], len(peers), time.Since(block.ReceivedAt))
 	}
 }
 
-// BroadcastTx will propagate the block to its connected peers. It will sort
-// out which peers do not contain the block in their block set and will do a
-// sqrt(peers) to determine the amount of peers we broadcast to.
+// BroadcastTx will propagate a transaction to all peers which are not known to
+// already have the given transaction.
 func (pm *ProtocolManager) BroadcastTx(hash common.Hash, tx *types.Transaction) {
 	// Broadcast transaction to a batch of peers not knowing about it
 	peers := pm.peers.PeersWithoutTx(hash)
 	//FIXME include this again: peers = peers[:int(math.Sqrt(float64(len(peers))))]
 	for _, peer := range peers {
-		peer.sendTransaction(tx)
+		peer.SendTransactions(types.Transactions{tx})
 	}
 	glog.V(logger.Detail).Infoln("broadcast tx to", len(peers), "peers")
 }
diff --git a/eth/metrics.go b/eth/metrics.go
new file mode 100644
index 000000000..950b50296
--- /dev/null
+++ b/eth/metrics.go
@@ -0,0 +1,28 @@
+package eth
+
+import (
+	"github.com/ethereum/go-ethereum/metrics"
+)
+
+var (
+	propTxnInPacketsMeter    = metrics.NewMeter("eth/prop/txns/in/packets")
+	propTxnInTrafficMeter    = metrics.NewMeter("eth/prop/txns/in/traffic")
+	propTxnOutPacketsMeter   = metrics.NewMeter("eth/prop/txns/out/packets")
+	propTxnOutTrafficMeter   = metrics.NewMeter("eth/prop/txns/out/traffic")
+	propHashInPacketsMeter   = metrics.NewMeter("eth/prop/hashes/in/packets")
+	propHashInTrafficMeter   = metrics.NewMeter("eth/prop/hashes/in/traffic")
+	propHashOutPacketsMeter  = metrics.NewMeter("eth/prop/hashes/out/packets")
+	propHashOutTrafficMeter  = metrics.NewMeter("eth/prop/hashes/out/traffic")
+	propBlockInPacketsMeter  = metrics.NewMeter("eth/prop/blocks/in/packets")
+	propBlockInTrafficMeter  = metrics.NewMeter("eth/prop/blocks/in/traffic")
+	propBlockOutPacketsMeter = metrics.NewMeter("eth/prop/blocks/out/packets")
+	propBlockOutTrafficMeter = metrics.NewMeter("eth/prop/blocks/out/traffic")
+	reqHashInPacketsMeter    = metrics.NewMeter("eth/req/hashes/in/packets")
+	reqHashInTrafficMeter    = metrics.NewMeter("eth/req/hashes/in/traffic")
+	reqHashOutPacketsMeter   = metrics.NewMeter("eth/req/hashes/out/packets")
+	reqHashOutTrafficMeter   = metrics.NewMeter("eth/req/hashes/out/traffic")
+	reqBlockInPacketsMeter   = metrics.NewMeter("eth/req/blocks/in/packets")
+	reqBlockInTrafficMeter   = metrics.NewMeter("eth/req/blocks/in/traffic")
+	reqBlockOutPacketsMeter  = metrics.NewMeter("eth/req/blocks/out/packets")
+	reqBlockOutTrafficMeter  = metrics.NewMeter("eth/req/blocks/out/traffic")
+)
diff --git a/eth/peer.go b/eth/peer.go
index c7045282b..088417aab 100644
--- a/eth/peer.go
+++ b/eth/peer.go
@@ -20,25 +20,18 @@ var (
 	errNotRegistered     = errors.New("peer is not registered")
 )
 
-type statusMsgData struct {
-	ProtocolVersion uint32
-	NetworkId       uint32
-	TD              *big.Int
-	CurrentBlock    common.Hash
-	GenesisBlock    common.Hash
-}
-
-type getBlockHashesMsgData struct {
-	Hash   common.Hash
-	Amount uint64
-}
+const (
+	maxKnownTxs    = 32768 // Maximum transactions hashes to keep in the known list (prevent DOS)
+	maxKnownBlocks = 1024  // Maximum block hashes to keep in the known list (prevent DOS)
+)
 
 type peer struct {
 	*p2p.Peer
 
 	rw p2p.MsgReadWriter
 
-	protv, netid int
+	version int // Protocol version negotiated
+	network int // Network ID being on
 
 	id string
 
@@ -46,27 +39,21 @@ type peer struct {
 	td   *big.Int
 	lock sync.RWMutex
 
-	genesis, ourHash common.Hash
-	ourTd            *big.Int
-
-	txHashes    *set.Set
-	blockHashes *set.Set
+	knownTxs    *set.Set // Set of transaction hashes known to be known by this peer
+	knownBlocks *set.Set // Set of block hashes known to be known by this peer
 }
 
-func newPeer(protv, netid int, genesis, head common.Hash, td *big.Int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
+func newPeer(version, network int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
 	id := p.ID()
 
 	return &peer{
 		Peer:        p,
 		rw:          rw,
-		genesis:     genesis,
-		ourHash:     head,
-		ourTd:       td,
-		protv:       protv,
-		netid:       netid,
+		version:     version,
+		network:     network,
 		id:          fmt.Sprintf("%x", id[:8]),
-		txHashes:    set.New(),
-		blockHashes: set.New(),
+		knownTxs:    set.New(),
+		knownBlocks: set.New(),
 	}
 }
 
@@ -103,68 +90,110 @@ func (p *peer) SetTd(td *big.Int) {
 	p.td.Set(td)
 }
 
-// sendTransactions sends transactions to the peer and includes the hashes
-// in it's tx hash set for future reference. The tx hash will allow the
-// manager to check whether the peer has already received this particular
-// transaction
-func (p *peer) sendTransactions(txs types.Transactions) error {
-	for _, tx := range txs {
-		p.txHashes.Add(tx.Hash())
+// MarkBlock marks a block as known for the peer, ensuring that the block will
+// never be propagated to this particular peer.
+func (p *peer) MarkBlock(hash common.Hash) {
+	// If we reached the memory allowance, drop a previously known block hash
+	for p.knownBlocks.Size() >= maxKnownBlocks {
+		p.knownBlocks.Pop()
 	}
+	p.knownBlocks.Add(hash)
+}
 
+// MarkTransaction marks a transaction as known for the peer, ensuring that it
+// will never be propagated to this particular peer.
+func (p *peer) MarkTransaction(hash common.Hash) {
+	// If we reached the memory allowance, drop a previously known transaction hash
+	for p.knownTxs.Size() >= maxKnownTxs {
+		p.knownTxs.Pop()
+	}
+	p.knownTxs.Add(hash)
+}
+
+// SendTransactions sends transactions to the peer and includes the hashes
+// in its transaction hash set for future reference.
+func (p *peer) SendTransactions(txs types.Transactions) error {
+	propTxnOutPacketsMeter.Mark(1)
+	for _, tx := range txs {
+		propTxnOutTrafficMeter.Mark(tx.Size().Int64())
+		p.knownTxs.Add(tx.Hash())
+	}
 	return p2p.Send(p.rw, TxMsg, txs)
 }
 
-func (p *peer) sendBlockHashes(hashes []common.Hash) error {
+// SendBlockHashes sends a batch of known hashes to the remote peer.
+func (p *peer) SendBlockHashes(hashes []common.Hash) error {
+	reqHashOutPacketsMeter.Mark(1)
+	reqHashOutTrafficMeter.Mark(int64(32 * len(hashes)))
+
 	return p2p.Send(p.rw, BlockHashesMsg, hashes)
 }
 
-func (p *peer) sendBlocks(blocks []*types.Block) error {
+// SendBlocks sends a batch of blocks to the remote peer.
+func (p *peer) SendBlocks(blocks []*types.Block) error {
+	reqBlockOutPacketsMeter.Mark(1)
+	for _, block := range blocks {
+		reqBlockOutTrafficMeter.Mark(block.Size().Int64())
+	}
 	return p2p.Send(p.rw, BlocksMsg, blocks)
 }
 
-func (p *peer) sendNewBlockHashes(hashes []common.Hash) error {
+// SendNewBlockHashes announces the availability of a number of blocks through
+// a hash notification.
+func (p *peer) SendNewBlockHashes(hashes []common.Hash) error {
+	propHashOutPacketsMeter.Mark(1)
+	propHashOutTrafficMeter.Mark(int64(32 * len(hashes)))
+
 	for _, hash := range hashes {
-		p.blockHashes.Add(hash)
+		p.knownBlocks.Add(hash)
 	}
 	return p2p.Send(p.rw, NewBlockHashesMsg, hashes)
 }
 
-func (p *peer) sendNewBlock(block *types.Block) error {
-	p.blockHashes.Add(block.Hash())
+// SendNewBlock propagates an entire block to a remote peer.
+func (p *peer) SendNewBlock(block *types.Block) error {
+	propBlockOutPacketsMeter.Mark(1)
+	propBlockOutTrafficMeter.Mark(block.Size().Int64())
 
+	p.knownBlocks.Add(block.Hash())
 	return p2p.Send(p.rw, NewBlockMsg, []interface{}{block, block.Td})
 }
 
-func (p *peer) sendTransaction(tx *types.Transaction) error {
-	p.txHashes.Add(tx.Hash())
-
-	return p2p.Send(p.rw, TxMsg, []*types.Transaction{tx})
+// RequestHashes fetches a batch of hashes from a peer, starting at from, going
+// towards the genesis block.
+func (p *peer) RequestHashes(from common.Hash) error {
+	glog.V(logger.Debug).Infof("Peer [%s] fetching hashes (%d) from %x...\n", p.id, downloader.MaxHashFetch, from[:4])
+	return p2p.Send(p.rw, GetBlockHashesMsg, getBlockHashesData{from, uint64(downloader.MaxHashFetch)})
 }
 
-func (p *peer) requestHashes(from common.Hash) error {
-	glog.V(logger.Debug).Infof("[%s] fetching hashes (%d) %x...\n", p.id, downloader.MaxHashFetch, from[:4])
-	return p2p.Send(p.rw, GetBlockHashesMsg, getBlockHashesMsgData{from, uint64(downloader.MaxHashFetch)})
+// RequestHashesFromNumber fetches a batch of hashes from a peer, starting at the
+// requested block number, going upwards towards the genesis block.
+func (p *peer) RequestHashesFromNumber(from uint64, count int) error {
+	glog.V(logger.Debug).Infof("Peer [%s] fetching hashes (%d) from #%d...\n", p.id, count, from)
+	return p2p.Send(p.rw, GetBlockHashesFromNumberMsg, getBlockHashesFromNumberData{from, uint64(count)})
 }
 
-func (p *peer) requestBlocks(hashes []common.Hash) error {
+// RequestBlocks fetches a batch of blocks corresponding to the specified hashes.
+func (p *peer) RequestBlocks(hashes []common.Hash) error {
 	glog.V(logger.Debug).Infof("[%s] fetching %v blocks\n", p.id, len(hashes))
 	return p2p.Send(p.rw, GetBlocksMsg, hashes)
 }
 
-func (p *peer) handleStatus() error {
+// Handshake executes the eth protocol handshake, negotiating version number,
+// network IDs, difficulties, head and genesis blocks.
+func (p *peer) Handshake(td *big.Int, head common.Hash, genesis common.Hash) error {
+	// Send out own handshake in a new thread
 	errc := make(chan error, 1)
 	go func() {
-		errc <- p2p.Send(p.rw, StatusMsg, &statusMsgData{
-			ProtocolVersion: uint32(p.protv),
-			NetworkId:       uint32(p.netid),
-			TD:              p.ourTd,
-			CurrentBlock:    p.ourHash,
-			GenesisBlock:    p.genesis,
+		errc <- p2p.Send(p.rw, StatusMsg, &statusData{
+			ProtocolVersion: uint32(p.version),
+			NetworkId:       uint32(p.network),
+			TD:              td,
+			CurrentBlock:    head,
+			GenesisBlock:    genesis,
 		})
 	}()
-
-	// read and handle remote status
+	// In the mean time retrieve the remote status message
 	msg, err := p.rw.ReadMsg()
 	if err != nil {
 		return err
@@ -175,31 +204,32 @@ func (p *peer) handleStatus() error {
 	if msg.Size > ProtocolMaxMsgSize {
 		return errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
 	}
-
-	var status statusMsgData
+	// Decode the handshake and make sure everything matches
+	var status statusData
 	if err := msg.Decode(&status); err != nil {
 		return errResp(ErrDecode, "msg %v: %v", msg, err)
 	}
-
-	if status.GenesisBlock != p.genesis {
-		return errResp(ErrGenesisBlockMismatch, "%x (!= %x)", status.GenesisBlock, p.genesis)
+	if status.GenesisBlock != genesis {
+		return errResp(ErrGenesisBlockMismatch, "%x (!= %x)", status.GenesisBlock, genesis)
 	}
-
-	if int(status.NetworkId) != p.netid {
-		return errResp(ErrNetworkIdMismatch, "%d (!= %d)", status.NetworkId, p.netid)
+	if int(status.NetworkId) != p.network {
+		return errResp(ErrNetworkIdMismatch, "%d (!= %d)", status.NetworkId, p.network)
 	}
-
-	if int(status.ProtocolVersion) != p.protv {
-		return errResp(ErrProtocolVersionMismatch, "%d (!= %d)", status.ProtocolVersion, p.protv)
+	if int(status.ProtocolVersion) != p.version {
+		return errResp(ErrProtocolVersionMismatch, "%d (!= %d)", status.ProtocolVersion, p.version)
 	}
-	// Set the total difficulty of the peer
-	p.td = status.TD
-	// set the best hash of the peer
-	p.head = status.CurrentBlock
-
+	// Configure the remote peer, and sanity check out handshake too
+	p.td, p.head = status.TD, status.CurrentBlock
 	return <-errc
 }
 
+// String implements fmt.Stringer.
+func (p *peer) String() string {
+	return fmt.Sprintf("Peer %s [%s]", p.id,
+		fmt.Sprintf("eth/%2d", p.version),
+	)
+}
+
 // peerSet represents the collection of active peers currently participating in
 // the Ethereum sub-protocol.
 type peerSet struct {
@@ -264,7 +294,7 @@ func (ps *peerSet) PeersWithoutBlock(hash common.Hash) []*peer {
 
 	list := make([]*peer, 0, len(ps.peers))
 	for _, p := range ps.peers {
-		if !p.blockHashes.Has(hash) {
+		if !p.knownBlocks.Has(hash) {
 			list = append(list, p)
 		}
 	}
@@ -279,7 +309,7 @@ func (ps *peerSet) PeersWithoutTx(hash common.Hash) []*peer {
 
 	list := make([]*peer, 0, len(ps.peers))
 	for _, p := range ps.peers {
-		if !p.txHashes.Has(hash) {
+		if !p.knownTxs.Has(hash) {
 			list = append(list, p)
 		}
 	}
diff --git a/eth/protocol.go b/eth/protocol.go
index 57805d9bd..bf9e155c5 100644
--- a/eth/protocol.go
+++ b/eth/protocol.go
@@ -7,11 +7,15 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 )
 
+// Supported versions of the eth protocol (first is primary).
+var ProtocolVersions = []uint{61, 60}
+
+// Number of implemented message corresponding to different protocol versions.
+var ProtocolLengths = []uint64{9, 8}
+
 const (
-	ProtocolVersion    = 60
 	NetworkId          = 0
-	ProtocolLength     = uint64(8)
-	ProtocolMaxMsgSize = 10 * 1024 * 1024
+	ProtocolMaxMsgSize = 10 * 1024 * 1024 // Maximum cap on the size of a protocol message
 )
 
 // eth protocol message codes
@@ -24,6 +28,7 @@ const (
 	GetBlocksMsg
 	BlocksMsg
 	NewBlockMsg
+	GetBlockHashesFromNumberMsg
 )
 
 type errCode int
@@ -72,8 +77,31 @@ type chainManager interface {
 	Status() (td *big.Int, currentBlock common.Hash, genesisBlock common.Hash)
 }
 
-// message structs used for RLP serialization
-type newBlockMsgData struct {
+// statusData is the network packet for the status message.
+type statusData struct {
+	ProtocolVersion uint32
+	NetworkId       uint32
+	TD              *big.Int
+	CurrentBlock    common.Hash
+	GenesisBlock    common.Hash
+}
+
+// getBlockHashesData is the network packet for the hash based block retrieval
+// message.
+type getBlockHashesData struct {
+	Hash   common.Hash
+	Amount uint64
+}
+
+// getBlockHashesFromNumberData is the network packet for the number based block
+// retrieval message.
+type getBlockHashesFromNumberData struct {
+	Number uint64
+	Amount uint64
+}
+
+// newBlockData is the network packet for the block propagation message.
+type newBlockData struct {
 	Block *types.Block
 	TD    *big.Int
 }
diff --git a/eth/protocol_test.go b/eth/protocol_test.go
index 60fa35443..4c1579d4e 100644
--- a/eth/protocol_test.go
+++ b/eth/protocol_test.go
@@ -39,15 +39,15 @@ func TestStatusMsgErrors(t *testing.T) {
 			wantError: errResp(ErrNoStatusMsg, "first msg has code 2 (!= 0)"),
 		},
 		{
-			code: StatusMsg, data: statusMsgData{10, NetworkId, td, currentBlock, genesis},
+			code: StatusMsg, data: statusData{10, NetworkId, td, currentBlock, genesis},
 			wantError: errResp(ErrProtocolVersionMismatch, "10 (!= 0)"),
 		},
 		{
-			code: StatusMsg, data: statusMsgData{ProtocolVersion, 999, td, currentBlock, genesis},
+			code: StatusMsg, data: statusData{uint32(ProtocolVersions[0]), 999, td, currentBlock, genesis},
 			wantError: errResp(ErrNetworkIdMismatch, "999 (!= 0)"),
 		},
 		{
-			code: StatusMsg, data: statusMsgData{ProtocolVersion, NetworkId, td, currentBlock, common.Hash{3}},
+			code: StatusMsg, data: statusData{uint32(ProtocolVersions[0]), NetworkId, td, currentBlock, common.Hash{3}},
 			wantError: errResp(ErrGenesisBlockMismatch, "0300000000000000000000000000000000000000000000000000000000000000 (!= %x)", genesis),
 		},
 	}
@@ -167,7 +167,7 @@ func newProtocolManagerForTesting(txAdded chan<- []*types.Transaction) *Protocol
 		db, _    = ethdb.NewMemDatabase()
 		chain, _ = core.NewChainManager(core.GenesisBlock(0, db), db, db, core.FakePow{}, em)
 		txpool   = &fakeTxPool{added: txAdded}
-		pm       = NewProtocolManager(ProtocolVersion, 0, em, txpool, core.FakePow{}, chain)
+		pm       = NewProtocolManager(0, em, txpool, core.FakePow{}, chain)
 	)
 	pm.Start()
 	return pm
@@ -188,7 +188,7 @@ func newTestPeer(pm *ProtocolManager) (*testPeer, <-chan error) {
 
 func (p *testPeer) handshake(t *testing.T) {
 	td, currentBlock, genesis := p.pm.chainman.Status()
-	msg := &statusMsgData{
+	msg := &statusData{
 		ProtocolVersion: uint32(p.pm.protVer),
 		NetworkId:       uint32(p.pm.netId),
 		TD:              td,
diff --git a/eth/sync.go b/eth/sync.go
index 82abb725f..47fd7363e 100644
--- a/eth/sync.go
+++ b/eth/sync.go
@@ -20,14 +20,6 @@ const (
 	txsyncPackSize = 100 * 1024
 )
 
-// blockAnnounce is the hash notification of the availability of a new block in
-// the network.
-type blockAnnounce struct {
-	hash common.Hash
-	peer *peer
-	time time.Time
-}
-
 type txsync struct {
 	p   *peer
 	txs []*types.Transaction
@@ -75,7 +67,7 @@ func (pm *ProtocolManager) txsyncLoop() {
 		// Send the pack in the background.
 		glog.V(logger.Detail).Infof("%v: sending %d transactions (%v)", s.p.Peer, len(pack.txs), size)
 		sending = true
-		go func() { done <- pack.p.sendTransactions(pack.txs) }()
+		go func() { done <- pack.p.SendTransactions(pack.txs) }()
 	}
 
 	// pick chooses the next pending sync.