IPv6 traffic may be carried through an MPLS IPv4 network without the use
of IPv6-over-IPv4 tunneling. This provides great savings in overhead,
signaling, and state information storage and also allows for routing
through the MPLS IPv4 network to adjust in response to changes in network
state. In one embodiment, an edge node of an MPLS IPv4 network resolves a
destination IPv6 network of a received IPv6 packet to an MPLS label
switched path. The resolution exploits received inter-domain routing
information. This information identifies the IPv4 address of an egress
node that is usable as a gateway to the destination network. Within the
inter-domain routing information, the IPv4 address may be encoded in IPv6
format.