diff --git a/htlcswitch/packet.go b/htlcswitch/packet.go
index cdaccedb..01e50d27 100644
--- a/htlcswitch/packet.go
+++ b/htlcswitch/packet.go
@@ -1,6 +1,7 @@
 package htlcswitch
 
 import (
+	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lnwire"
 )
 
@@ -35,6 +36,20 @@ type htlcPacket struct {
 	// outgoing channel.
 	outgoingHTLCID uint64
 
+	// sourceRef is used by forwarded htlcPackets to locate incoming Add
+	// entry in a fwdpkg owned by the incoming link. This value can be nil
+	// if there is no such entry, e.g. switch initiated payments.
+	sourceRef *channeldb.AddRef
+
+	// destRef is used to locate a settle/fail entry in the outgoing link's
+	// fwdpkg. If sourceRef is non-nil, this reference should be to a
+	// settle/fail in response to the sourceRef.
+	destRef *channeldb.SettleFailRef
+
+	// incomingAmount is the value in milli-satoshis that arrived on an
+	// incoming link.
+	incomingAmount lnwire.MilliSatoshi
+
 	// amount is the value of the HTLC that is being created or modified.
 	amount lnwire.MilliSatoshi
 
@@ -50,10 +65,10 @@ type htlcPacket struct {
 	// encrypted with any shared secret.
 	localFailure bool
 
-	// isRouted is set to true if the incomingChanID and incomingHTLCID fields
-	// of a forwarded fail packet are already set and do not need to be looked
-	// up in the circuit map.
-	isRouted bool
+	// hasSource is set to true if the incomingChanID and incomingHTLCID
+	// fields of a forwarded fail packet are already set and do not need to
+	// be looked up in the circuit map.
+	hasSource bool
 
 	// isResolution is set to true if this packet was actually an incoming
 	// resolution message from an outside sub-system. We'll treat these as
@@ -61,4 +76,32 @@ type htlcPacket struct {
 	// encrypt all errors related to this packet as if we were the first
 	// hop.
 	isResolution bool
+
+	// circuit holds a reference to an Add's circuit which is persisted in
+	// the switch during successful forwarding.
+	circuit *PaymentCircuit
+}
+
+// inKey returns the circuit key used to identify the incoming htlc.
+func (p *htlcPacket) inKey() CircuitKey {
+	return CircuitKey{
+		ChanID: p.incomingChanID,
+		HtlcID: p.incomingHTLCID,
+	}
+}
+
+// outKey returns the circuit key used to identify the outgoing, forwarded htlc.
+func (p *htlcPacket) outKey() CircuitKey {
+	return CircuitKey{
+		ChanID: p.outgoingChanID,
+		HtlcID: p.outgoingHTLCID,
+	}
+}
+
+// keystone returns a tuple containing the incoming and outgoing circuit keys.
+func (p *htlcPacket) keystone() Keystone {
+	return Keystone{
+		InKey:  p.inKey(),
+		OutKey: p.outKey(),
+	}
 }