Process and apparatus for speeding-up layer-2 and layer-3 routing, and for determining layer-2 reachability, through a plurality of subnetworks

摘要

A communication apparatus contains a first table having entries each storing a data-link-layer path to a second communication apparatus, and a second table storing a pointer to the entry of the first table, storing the data-link-layer path to the second communication apparatus, corresponding to a network-layer address of one of the at least one other communication apparatus. In addition, a process for determining layer-2 reachability between first and second communication apparatuses, identifies first and second layer-2-connected communication networks to which first and second interfaces of first and second routers are connected, where, on a layer-3 communication path between the first and second communication apparatuses, the first router is located nearest the first communication apparatus and the second router is located nearest the second communication apparatus. When first and second layer-2-connected communication networks are identical, the layer-2 reachability is determined.