diff --git a/blockservice/mock.go b/blockservice/mock.go
index 0305c92fb..2b646386c 100644
--- a/blockservice/mock.go
+++ b/blockservice/mock.go
@@ -5,12 +5,13 @@ import (
 
 	bitswap "github.com/jbenet/go-ipfs/exchange/bitswap"
 	tn "github.com/jbenet/go-ipfs/exchange/bitswap/testnet"
-	"github.com/jbenet/go-ipfs/routing/mock"
+	mock "github.com/jbenet/go-ipfs/routing/mock"
+	delay "github.com/jbenet/go-ipfs/util/delay"
 )
 
 // Mocks returns |n| connected mock Blockservices
 func Mocks(t *testing.T, n int) []*BlockService {
-	net := tn.VirtualNetwork()
+	net := tn.VirtualNetwork(delay.Fixed(0))
 	rs := mock.VirtualRoutingServer()
 	sg := bitswap.NewSessionGenerator(net, rs)
 
diff --git a/exchange/bitswap/bitswap_test.go b/exchange/bitswap/bitswap_test.go
index d57132fba..21b259a7e 100644
--- a/exchange/bitswap/bitswap_test.go
+++ b/exchange/bitswap/bitswap_test.go
@@ -11,13 +11,14 @@ import (
 	blocksutil "github.com/jbenet/go-ipfs/blocks/blocksutil"
 	tn "github.com/jbenet/go-ipfs/exchange/bitswap/testnet"
 	mock "github.com/jbenet/go-ipfs/routing/mock"
+	delay "github.com/jbenet/go-ipfs/util/delay"
 	testutil "github.com/jbenet/go-ipfs/util/testutil"
 )
 
 func TestClose(t *testing.T) {
 	// TODO
 	t.Skip("TODO Bitswap's Close implementation is a WIP")
-	vnet := tn.VirtualNetwork()
+	vnet := tn.VirtualNetwork(delay.Fixed(0))
 	rout := mock.VirtualRoutingServer()
 	sesgen := NewSessionGenerator(vnet, rout)
 	bgen := blocksutil.NewBlockGenerator()
@@ -31,7 +32,7 @@ func TestClose(t *testing.T) {
 
 func TestGetBlockTimeout(t *testing.T) {
 
-	net := tn.VirtualNetwork()
+	net := tn.VirtualNetwork(delay.Fixed(0))
 	rs := mock.VirtualRoutingServer()
 	g := NewSessionGenerator(net, rs)
 
@@ -48,7 +49,7 @@ func TestGetBlockTimeout(t *testing.T) {
 
 func TestProviderForKeyButNetworkCannotFind(t *testing.T) {
 
-	net := tn.VirtualNetwork()
+	net := tn.VirtualNetwork(delay.Fixed(0))
 	rs := mock.VirtualRoutingServer()
 	g := NewSessionGenerator(net, rs)
 
@@ -69,7 +70,7 @@ func TestProviderForKeyButNetworkCannotFind(t *testing.T) {
 
 func TestGetBlockFromPeerAfterPeerAnnounces(t *testing.T) {
 
-	net := tn.VirtualNetwork()
+	net := tn.VirtualNetwork(delay.Fixed(0))
 	rs := mock.VirtualRoutingServer()
 	block := blocks.NewBlock([]byte("block"))
 	g := NewSessionGenerator(net, rs)
@@ -121,7 +122,7 @@ func PerformDistributionTest(t *testing.T, numInstances, numBlocks int) {
 	if testing.Short() {
 		t.SkipNow()
 	}
-	net := tn.VirtualNetwork()
+	net := tn.VirtualNetwork(delay.Fixed(0))
 	rs := mock.VirtualRoutingServer()
 	sg := NewSessionGenerator(net, rs)
 	bg := blocksutil.NewBlockGenerator()
@@ -181,7 +182,7 @@ func TestSendToWantingPeer(t *testing.T) {
 		t.SkipNow()
 	}
 
-	net := tn.VirtualNetwork()
+	net := tn.VirtualNetwork(delay.Fixed(0))
 	rs := mock.VirtualRoutingServer()
 	sg := NewSessionGenerator(net, rs)
 	bg := blocksutil.NewBlockGenerator()
diff --git a/exchange/bitswap/testnet/network.go b/exchange/bitswap/testnet/network.go
index 7f82bcdce..b8f61b413 100644
--- a/exchange/bitswap/testnet/network.go
+++ b/exchange/bitswap/testnet/network.go
@@ -10,6 +10,7 @@ import (
 	bsnet "github.com/jbenet/go-ipfs/exchange/bitswap/network"
 	peer "github.com/jbenet/go-ipfs/peer"
 	"github.com/jbenet/go-ipfs/util"
+	delay "github.com/jbenet/go-ipfs/util/delay"
 )
 
 type Network interface {
@@ -33,14 +34,16 @@ type Network interface {
 
 // network impl
 
-func VirtualNetwork() Network {
+func VirtualNetwork(d delay.D) Network {
 	return &network{
 		clients: make(map[util.Key]bsnet.Receiver),
+		delay:   d,
 	}
 }
 
 type network struct {
 	clients map[util.Key]bsnet.Receiver
+	delay   delay.D
 }
 
 func (n *network) Adapter(p peer.Peer) bsnet.BitSwapNetwork {
@@ -84,13 +87,15 @@ func (n *network) deliver(
 		return errors.New("Invalid input")
 	}
 
+	n.delay.Wait()
+
 	nextPeer, nextMsg := r.ReceiveMessage(context.TODO(), from, message)
 
 	if (nextPeer == nil && nextMsg != nil) || (nextMsg == nil && nextPeer != nil) {
 		return errors.New("Malformed client request")
 	}
 
-	if nextPeer == nil && nextMsg == nil {
+	if nextPeer == nil && nextMsg == nil { // no response to send
 		return nil
 	}
 
diff --git a/exchange/bitswap/testnet/network_test.go b/exchange/bitswap/testnet/network_test.go
index 0bfb0cb1e..7a9f48e2d 100644
--- a/exchange/bitswap/testnet/network_test.go
+++ b/exchange/bitswap/testnet/network_test.go
@@ -9,11 +9,12 @@ import (
 	bsmsg "github.com/jbenet/go-ipfs/exchange/bitswap/message"
 	bsnet "github.com/jbenet/go-ipfs/exchange/bitswap/network"
 	peer "github.com/jbenet/go-ipfs/peer"
+	delay "github.com/jbenet/go-ipfs/util/delay"
 	testutil "github.com/jbenet/go-ipfs/util/testutil"
 )
 
 func TestSendRequestToCooperativePeer(t *testing.T) {
-	net := VirtualNetwork()
+	net := VirtualNetwork(delay.Fixed(0))
 
 	idOfRecipient := []byte("recipient")
 
@@ -60,7 +61,7 @@ func TestSendRequestToCooperativePeer(t *testing.T) {
 }
 
 func TestSendMessageAsyncButWaitForResponse(t *testing.T) {
-	net := VirtualNetwork()
+	net := VirtualNetwork(delay.Fixed(0))
 	idOfResponder := []byte("responder")
 	waiter := net.Adapter(testutil.NewPeerWithIDString("waiter"))
 	responder := net.Adapter(testutil.NewPeerWithID(idOfResponder))