Method and Apparatus for Exchanging Routing Information and the Establishment of Connectivity Across Multiple Network Areas

Abstract

Routes may be installed across multiple link state protocol controlled Ethernet network areas by causing ABBs to leak I-SID information advertised by BEBs in a L1 network area into an L2 network area. ABBs will only leak I-SIDs for BEBs where it is the closest ABB for that BEB. Where another ABB on the L2 network also leaks the same I-SID into the L2 network area from another L1 network area, the I-SID is of multi-area interest. ABBs will advertise I-SIDs that are common to the L1 and L2 networks back into their respective L1 network. Within each L1 and L2 network area, forwarding state will be installed between network elements advertising common interest in an ISID, so that multi-area paths may be created to span the L1/L2/L1 network areas. The L1/L2/L1 network structure may recurse an arbitrary number of times.

What is claimed is: 
     
         1 - 21 . (canceled) 
     
     
         22 . An Area Boundary Bridge (ABB), comprising:
 a set of first communication interfaces for coupling the ABB to a first network area, the first network area being controlled by a link state protocol;
 a set of second communication interfaces for coupling the ABB to a second network area comprising a plurality of Backbone Edge Bridges; 
 at least one ABB processing element; and 
 at least one respective storage element coupled to each respective ABB processing element, the at least one respective storage element storing respective instructions for execution by the respective ABB processing element, the respective instructions comprising: 
 instructions executable by the respective ABB processing element to receive, on any of the second communication interfaces, community of interest identifiers associated with Backbone Edge Bridges (BEBs) reachable via any the second communication interfaces; 
 instructions executable by the respective ABB processing element to select, from the community of interest identifiers received on any of the second communication interfaces, respective community of interest identifiers for advertisement into the first network area from respective first communication interfaces; and 
 instructions executable by the respective ABB processing element to advertise the respective community of interest identifiers from the first communication interfaces as being associated with a virtual BEB. 
   
     
     
         23 . The ABB of  claim 22 , wherein the instructions executable by the respective ABB processing element to advertise community of interest identifiers from the respective first communication interfaces as being associated with a virtual BEB comprise instructions executable to advertise the community of interest identifiers as being associated with the virtual BEB to represent the second network area in the first network area as a BEB of the first network area. 
     
     
         24 . The ABB of  claim 23 , wherein execution of the instructions executable to advertise the community of interest identifiers as being associated with the virtual BEB to represent the second network area in the first network area as a BEB of the first network area results in the virtual BEB appearing to participate in the link state protocol of the first network area. 
     
     
         25 . The ABB of  claim 22 , wherein:
 the respective instructions comprise instructions executable by the respective ABB processing element to receive on respective first communication interfaces respective community of interest identifiers associated with respective BEBs that are reachable via the respective first communication interfaces; and   the instructions executable by the respective ABB processing element to select, from the community of interest identifiers received on any of the second communication interfaces, respective community of interest identifiers for advertisement into the first network area from respective first communication interfaces comprise instructions executable to select community of interest identifiers that have been received on both the respective first communication interfaces and any of the second communication interfaces.   
     
     
         26 . The ABB of  claim 22 , wherein the respective instructions comprise instructions executable by the respective ABB processing element to advertise from respective second communication interfaces community of interest identifiers associated with BEBs of the first network area that are reachable via the respective second communication interfaces. 
     
     
         27 . The ABB of  claim 26 , wherein the community of interest identifiers associated with BEBs of the first network area that are reachable via the respective second communication interfaces are community of interest identifiers received on first communication interfaces of the ABB. 
     
     
         28 . The ABB of  claim 27 , wherein the instructions executable by the respective ABB processing element to advertise from the second communication interfaces community of interest identifiers received on first communication interfaces of the ABB comprise instructions executable to advertise only community of interest identifiers associated with BEBs in the first network area that are deemed closer to the respective ABB than to any other ABB coupled to the first network area. 
     
     
         29 . The ABB of  claim 28 , wherein the instructions executable to advertise only community of interest identifiers associated with BEBs in the first network area that are deemed closer to the respective ABB than to any other ABB coupled to the first network area comprise:
 instructions executable to receive, on the first set of communication interfaces from BEBs of the first network area, link state protocol advertisements comprising at least one respective measure of distance associated with each BEB from which the link state protocol advertisements are received;   instructions executable to determine which BEBs are closer to the respective ABB than to any other ABB coupled to the first network area based on the respective measures of distance; and   instructions executable to determine community of interest identifiers associated with the BEBs that are closer to the respective ABB than to any other ABB coupled to the first network area based on the respective measures of distance.   
     
     
         30 . The ABB of  claim 22 , wherein the first link state protocol controlled network area is a link state protocol controlled Ethernet network area. 
     
     
         31 . The ABB of  claim 22 , wherein the first link state protocol controlled network is controlled by an IS-IS link state protocol. 
     
     
         32 . The ABB of  claim 22 , wherein the community of interest identifiers are service instance identifiers (I-SIDs). 
     
     
         33 . The ABB of  claim 30 , wherein the instructions executable by the respective ABB processing element to advertise community of interest identifiers received on second communication interfaces from the respective first communication interfaces comprise instructions executable by the respective ABB processing element to advertise a media access control (MAC) address of the ABB, respective I-SIDs received on the respective second communication interfaces, and respective MAC addresses of Backbone Edge Bridges (BEBs) associated with the respective I-SIDs. 
     
     
         34 . The ABB of  claim 33 , wherein the instructions executable by the respective ABB processing element to advertise a media access control (MAC) address of the ABB, respective I-SIDs received on the respective second communication interfaces, and respective MAC addresses of Backbone Edge Bridges (BEBs) associated with the respective I-SIDs comprise instructions executable to advertise a respective MAC address of at least one virtual BEB and at least one respective I-SID associated with the at least one virtual BEB. 
     
     
         35 . The ABB of  claim 22 , wherein:
 the instructions executable by the respective ABB processing element to advertise the respective community of interest identifiers from the first communication interfaces as being associated with a virtual BEB comprise instructions executable to send Level X link state protocol messages into the first network area; and   the instructions executable by the respective ABB processing element to receive, on any of the second communication interfaces, community of interest identifiers associated with BEBs reachable via any of the second communication interfaces comprise instructions executable to receive Level X+1 link state protocol messages.   
     
     
         36 . The ABB of  claim 22 , wherein the ABB maintains:
 Level X forwarding information for the first network area;   Level X+1 forwarding information for the second network area; and   Level X/X+1 forwarding information comprising community of interest identifier associations between the Level X forwarding information and the Level X+1 forwarding information.   
     
     
         37 . The ABB of  claim 36 , wherein the ABB maintains:
 Level X link state information for the first network area; and   Level X+1 link state information for the second network area.   
     
     
         38 . The ABB of  claim 36 , wherein the instructions further comprise:
 instructions executable by the ABB processing elements to perform a Level X link state routing process for the first network area; and   instructions executable by the ABB processing elements to perform a Level X+1 link state routing process for the second network area.   
     
     
         39 . The ABB of  claim 22 , wherein the storage elements are configured to store:
 Level X forwarding information for the first network area;   Level X+1 forwarding information for the second network area; and   Level X/X+1 forwarding information comprising community of interest identifier associations between the Level X forwarding information and the Level X+1 forwarding information.   
     
     
         40 . The ABB of  claim 39 , wherein:
 the Level X forwarding information is Level 1 forwarding information;   the Level X+1 forwarding information is Level 2 forwarding information; and   the Level X/X+1 forwarding information is Level 1/2 forwarding information comprising community of interest identifier associations between the Level 1 forwarding information and the Layer 2 forwarding information.   
     
     
         41 . The ABB of  claim 22 , wherein the storage elements are configured to store:
 Level X link state information for the first network area; and   Level X+1 link state information for the second network area.   
     
     
         42 . The ABB of  claim 41 , wherein:
 the Level X link state information is Level 1 link state information; and   the Level X+1 link state information is Level 2 link state information.   
     
     
         43 . The ABB of  claim 22 , wherein the instructions comprise:
 instructions executable by the ABB processing elements to perform a Level X link state routing process for the first network area; and   instructions executable by the ABB processing elements to perform a Level X+1 μlnk state routing process for the second network area.   
     
     
         44 . The ABB of  claim 43 , wherein:
 the Level X link state routing process is a Level 1 link state routing process; and   the Level X+1 link state routing process is Level 2 link state routing process.