Virtual routers within a single physical router share a centralized data
plane containing a centralized switch fabric and a plurality of physical
network interfaces, each assigned to only one virtual router. Using a
logical cut-through device between a pair of virtual routers designated
respectively client and server, packet forwarding information from the
server is imported into the client, which creates, allocates, and
maintains a data structure for the imported information, which then
resides on the client interfaces. This imported forwarding information is
then integrated into a single forwarding table that is used to recognize
an incoming packet at the client and forward it appropriately out through
a server interface with a single packet forwarding decision in a single
transit through the switch fabric. Within a physical router, a client
virtual router can communicate with multiple servers and can concurrently
function as a server to multiple clients.