Patent ID: 6792471
Filing Date: 2004-09-14
Classification: H04L

Abstract:
A process for determining layer-2 reachability between first and second communication apparatuses each connected to a layer-3 communication network comprised of at least one router and a plurality of subnetworks logically defined over at least one layer-2-connected communication network; said process comprising the steps of:(a) determining a layer-3 communication path connecting said first communication apparatus to said second communication apparatus, through a portion or all of said at least one router and said plurality of subnetworks, based on a layer-3 address of the second communication apparatus, where a first router is connected to said first communication apparatus through a first interface and a first subnetwork among said plurality of subnetworks on the determined layer-3 communication path, and a second router is connected to the second communication apparatus through a second interface and a second subnetwork among said plurality of subnetworks on the determined layer-3 communication path, wherein at least said first and second subnetworks are logically defined over said at least one layer-2 connected communication network; (b) identifying a first layer-2 communication network among said at least one layer-2-connected communication network to which said first interface is connected based on interface-network correspondence information associating said first interface to said first layer-2 communication network; (c) identifying a second layer-2 communication network among said at least one layer-2-connected communication network to which said second interface is connected based on interface-network correspondence information associating said second interface to said second layer-2 communication network; and (d) facilitating layer-2 communications between said first and second communication apparatuses when said identified first and second layer-2 communication networks are identical, wherein the identical layer-2 communication network logically defines at least said first and second subnetworks.