A dense virtual router packet switching system includes a memory divided into
context
areas for a set of virtual private routed networks (VPRNs). Each context area includes
a routing table and routing protocol state information for a corresponding VPRN.
Each of a set of different routing tasks operates with a separate routing table
and separate routing protocol state information to realize a corresponding virtual
router. Context selection logic selectively couples the routing tasks to the different
context areas of the memory to realize a set of virtual routers for all the VPRNs.
The system supports a large number of routes by exploiting the segmentation of
the VPRNs. Rather than having a single large routing table and associated routing
process, which can load hardware resources in proportion to the square of the number
of routes in the routing table, routes are distributed among a number of VPRNs
having generally smaller tables and correspondingly less processing demand.