Failure Notification in a Network having Serially Connected Nodes

Abstract

Multicast capabilities of a link state protocol controlled network are used to accelerate the flooding advertisement of topology change notifications within portions of the network. This flooding mechanism may be particularly efficient in a network with a large number of two-connected nodes such as a ring network architecture. A control plane specific multicast group address is used when flooding topology change notifications, and a process such as reverse path forwarding check is used as an additional control on forwarding of the notification to prevent looping of control plane packets. Two-connected nodes insert a forwarding entry into their FIB to enable frames containing the control message to be forwarded via the data plane on to the downstream node so that propagation of the control message along a chain of two-connected nodes may occur at data plane speeds.

What is claimed is: 
     
         1 - 12 . (canceled) 
     
     
         13 . A node for a link-state protocol controlled Ethernet network, the node comprising:
 a routing element configured:
 to exchange link state information with peer nodes; 
 to advertise, in link-state advertisements, membership in an I-SID used exclusively for control plane notifications; 
 to instantiate respective source-specific multicast trees routed at other nodes based on received link state information; and 
 to receive from root nodes of the respective source-specific multicast trees multicast notifications of topology changes associated with the root nodes and the I-SID used exclusively for control plane notifications; and 
   a reverse path forwarding check element configured:
 to perform a reverse path forwarding check (RPFC) on received multicast notifications of topology changes; 
 to discard received multicast notifications that fail the RPFC; and 
 to use normal filtering and flooding mechanisms for the notifications that pass the RPFC. 
   
     
     
         14 . The node of  claim 13 , wherein the routing element is further configured:
 to use received link state information to instantiate a respective source-specific multicast tree routed at the node; and   to use a source-specific Ethernet MAC address associated with the node and the common I-SID to send multicast notifications of topology changes to the members of the respective source-specific multicast tree.   
     
     
         15 . The node of  claim 13 , wherein the control plane notifications comprise a control plane specific multicast address. 
     
     
         16 . The node of  claim 15 , wherein the control plane specific multicast address is a (*,G) multicast address common to nodes on the respective source-specific multicast tree. 
     
     
         17 . The node of  claim 13 , wherein the routing element is configured to acknowledge notifications of topology changes that pass the RPFC. 
     
     
         18 . The node of  claim 13 , wherein the routing element is configured to acknowledge a notification of a topology change that passes the RPFC to a first node that sent the notification of the topology changes that passed the RPFC. 
     
     
         19 . The node of  claim 13 , wherein the routing element is configured to acknowledge a notification of a topology change that passes the RPFC to a first node that sent the notification of the topology changes that passed the RPFC only when the node is two-connected between the first node and another node. 
     
     
         20 . The node of  claim 13 , wherein the control plane notifications comprise source-specific multicast addresses. 
     
     
         21 . The node of  claim 20 , wherein the source-specific multicast addresses are (S,G) multicast addresses associated with the root nodes of the respective source-specific multicast trees.