Scaling OAM for Point-to-Point Trunking

Abstract

A shared (proxy) OAM session is performed in a packet-based network on behalf of a plurality of connections. First and second connections are each routed between respective nodes of the network for carrying data traffic. The second connection shares a portion of the routing of the first connection. The shared OAM session is performed along a path which is co-routed with at least part of the shared portion of the routing of the first connection and the second connection. Failure notification signalling is propagated to an endpoint node of each of the first and second connections when the shared OAM session indicates a failure has occurred. The use of a shared OAM session reduces processing at nodes and reduces OAM traffic. Each connection can be a trunk, such as a PBT/PBB-TE trunk, or a service carried within a trunk.

1 - 44 . (canceled) 
     
     
         45 . A packet-based network comprising:
 a plurality of nodes having a first connection routed on a first path between a first pair of endpoint nodes and a second connection routed on a second path between a second pair of endpoint nodes, the first and second paths having a shared path portion;   the first pair of endpoint nodes being configured to establish a first OAM session between the first pair of endpoint nodes, the first OAM session exchanging messages between the endpoints of the first connection at a first rate;   the second pair of endpoint nodes being configured to establish a second OAM session between the second pair of endpoint nodes, the second OAM session exchanging messages between the endpoints of the second connection at a second rate;   an intermediate node on the shared path portion and another node on the shared path portion being configured to establish a third OAM session as a shared OAM session between the intermediate node and the other node, the shared OAM session exchanging messages between the intermediate node and the other node at a third rate which is faster than the first and second rates; and   the intermediate node being configured to provide fault notification information from the shared OAM session to the first and second OAM sessions when the shared OAM session indicates that a fault has occurred.   
     
     
         46 . The network of  claim 45 , wherein the intermediate node is configured:
 to store state;   to monitor for a fault condition in the shared OAM session; and   to use the stored state to provide the fault notification information to the first and second OAM sessions when the fault condition occurs.   
     
     
         47 . The network of  claim 46 , wherein state is configured per-connection and the intermediate node is configured to provide the fault notification information by providing fault indication information on a per-connection basis according to which connection is affected by the fault condition. 
     
     
         48 . The network of  claim 47 , wherein the fault indication information is an Alarm Indication Signal (AIS). 
     
     
         49 . The network of  claim 46 , wherein the state stored at the intermediate node comprises information identifying at least one leg of a connection passing through the intermediate node and information associating the shared OAM session with the connection. 
     
     
         50 . The network of  claim 49 , wherein the intermediate node is configured to forward traffic between ports of the intermediate node according to stored forwarding information which comprises a combination of a destination address and another identifier. 
     
     
         51 . The network of  claim 50 , wherein the forwarding information specifies a destination MAC address and a VLAN identifier carried within an outer header of a data frame. 
     
     
         52 . The network of  claim 46 , wherein the stored state comprises a list of nodes to be notified if the fault condition occurs. 
     
     
         53 . The network of  claim 52 , wherein the stored state comprises a list of nodes that are endpoints of connections that share the shared path portion and the intermediate node is configured to send fault notification information only to nodes affected by the fault condition. 
     
     
         54 . The network of  claim 45 , wherein endpoint nodes of the first connection are connected via a working path and a protection path, the working path comprising the first connection, and the first pair of endpoint nodes is configured:
 to monitor, at the endpoint nodes of the first connection, for a fault condition using the shared OAM session;   to exchange protection switching signaling between the endpoint nodes of the connection using the protection path; and   to cause traffic to be switched to the protection path when a fault condition occurs on the first connection.   
     
     
         55 . The network of  claim 45 , wherein the shared OAM session comprises a continuity check and the intermediate node is configured to detect when a continuity fault occurs. 
     
     
         56 . The network of  claim 45 , wherein the first connection and the second connection are Provider Backbone Transport (PBT)/Provider Backbone Bridging-Traffic Engineering (PBB-TE) trunks. 
     
     
         57 . The network of  claim 45 , wherein:
 the first OAM session is bi-directional;   the second OAM session is bi-directional; and   the shared OAM session is bi-directional along at least part of the shared path portion.   
     
     
         58 . The network of  claim 45 , wherein the first rate is equal to the second rate. 
     
     
         59 . A packet-based network, comprising:
 a first pair of endpoint nodes configured to establish a first bi-directional end-to-end OAM session on a first connection through the network, the first connection extending over a first path through the network;   a second pair of endpoint nodes configured to establish a second bi-directional end-to-end OAM session on a second connection through the network, the second connection extending over a second path through the network, the second path through the network and the first path through the network having a shared portion where the first and second paths share a common route through the network; and   a pair of intermediate nodes configured to implement the first bi-directional end-to-end OAM session and the second bi-directional end-to-end OAM session on at least part of the shared portion as a third bi-directional OAM session along the at least part of the shared portion, the pair of intermediate nodes being configured to provide fault notification information to the first and second pairs of endpoint nodes when the third bi-directional OAM session indicates that a fault has occurred on the at least part of the shared portion.   
     
     
         60 . The network of  claim 59 , wherein the fault notification information is an Alarm Indication Signal (AIS). 
     
     
         61 . The network of  claim 59 , wherein the third bi-directional OAM session comprises a continuity check and the pair of intermediate nodes is configured to detect when a continuity check fault occurs. 
     
     
         62 . The network of  claim 59 , wherein:
 the first bi-directional OAM session exchanges messages between the endpoints of the first connection at a first rate;   the second bi-directional OAM session exchanges messages between the endpoints of the second connection at a second rate; and   the third bi-directional OAM session exchanges messages between the pair of intermediate nodes at a third rate which is faster than the first and second rates.   
     
     
         63 . The network of  claim 62 , wherein the first rate is equal to the second rate. 
     
     
         64 . The network of  claim 59 , wherein the first connection and the second connection are Provider Backbone Transport (PBT)/Provider Backbone Bridging-Traffic Engineering (PBB-TE) trunks.