diff --git a/router/network_overlay.go b/router/network_overlay.go
new file mode 100644
index 00000000..8d80594b
--- /dev/null
+++ b/router/network_overlay.go
@@ -0,0 +1,46 @@
+package router
+
+// Interface to overlay network packet handling
+type NetworkOverlay interface {
+	Overlay
+
+	// The routes have changed, so any cached information should
+	// be discarded.
+	InvalidateRoutes()
+
+	// A mapping of a short id to a peer has changed
+	InvalidateShortIDs()
+
+	// Start consuming forwarded packets.
+	StartConsumingPackets(*Peer, *Peers, OverlayConsumer) error
+}
+
+// When a consumer is called, the decoder will already have been used
+// to decode the frame.
+type OverlayConsumer func(ForwardPacketKey) FlowOp
+
+// All of the machinery to forward packets to a particular peer
+type OverlayForwarder interface {
+	OverlayConnection
+	// Forward a packet across the connection.  May be called as soon
+	// as the overlay connection is created, in particular before
+	// Confirm().  The return value nil means the key could not be
+	// handled by this forwarder.
+	Forward(ForwardPacketKey) FlowOp
+}
+
+type NullNetworkOverlay struct{ NullOverlay }
+
+func (NullNetworkOverlay) InvalidateRoutes() {
+}
+
+func (NullNetworkOverlay) InvalidateShortIDs() {
+}
+
+func (NullNetworkOverlay) StartConsumingPackets(*Peer, *Peers, OverlayConsumer) error {
+	return nil
+}
+
+func (NullNetworkOverlay) Forward(ForwardPacketKey) FlowOp {
+	return DiscardingFlowOp{}
+}
diff --git a/router/overlay.go b/router/overlay.go
index 27dd896d..13fd0428 100644
--- a/router/overlay.go
+++ b/router/overlay.go
@@ -16,21 +16,6 @@ type Overlay interface {
 	Diagnostics() interface{}
 }
 
-// Interface to overlay network packet handling
-type NetworkOverlay interface {
-	Overlay
-
-	// The routes have changed, so any cached information should
-	// be discarded.
-	InvalidateRoutes()
-
-	// A mapping of a short id to a peer has changed
-	InvalidateShortIDs()
-
-	// Start consuming forwarded packets.
-	StartConsumingPackets(*Peer, *Peers, OverlayConsumer) error
-}
-
 type OverlayConnectionParams struct {
 	RemotePeer *Peer
 
@@ -62,10 +47,6 @@ type OverlayConnectionParams struct {
 	Features map[string]string
 }
 
-// When a consumer is called, the decoder will already have been used
-// to decode the frame.
-type OverlayConsumer func(ForwardPacketKey) FlowOp
-
 // All of the machinery to manage overlay connectivity to a particular
 // peer
 type OverlayConnection interface {
@@ -95,16 +76,6 @@ type OverlayConnection interface {
 	DisplayName() string
 }
 
-// All of the machinery to forward packets to a particular peer
-type OverlayForwarder interface {
-	OverlayConnection
-	// Forward a packet across the connection.  May be called as soon
-	// as the overlay connection is created, in particular before
-	// Confirm().  The return value nil means the key could not be
-	// handled by this forwarder.
-	Forward(ForwardPacketKey) FlowOp
-}
-
 type NullOverlay struct{}
 
 func (NullOverlay) AddFeaturesTo(map[string]string) {
@@ -137,19 +108,3 @@ func (NullOverlay) ControlMessage(byte, []byte) {
 func (NullOverlay) DisplayName() string {
 	return "null"
 }
-
-type NullNetworkOverlay struct{ NullOverlay }
-
-func (NullNetworkOverlay) InvalidateRoutes() {
-}
-
-func (NullNetworkOverlay) InvalidateShortIDs() {
-}
-
-func (NullNetworkOverlay) StartConsumingPackets(*Peer, *Peers, OverlayConsumer) error {
-	return nil
-}
-
-func (NullNetworkOverlay) Forward(ForwardPacketKey) FlowOp {
-	return DiscardingFlowOp{}
-}