Multicast implementation in a link state protocol controlled ethernet network

Abstract

Forwarding state is installed for sparse multicast trees in a link state protocol controlled Ethernet network by enabling intermediate nodes to install state for one or more physical multicast trees, each of which may have multiple logical multicast trees mapped to it. By mapping multiple logical multicasts to a particular physical multicast, and installing state for the physical multicast, fewer FIB entries are required to implement the multiple multicasts. Mapping may be performed by destination nodes before advertising membership in the physical multicast, or may be performed by the intermediate nodes before installing state when a destination node advertises membership in a logical multicast. Intermediate nodes will install state for the physical multicast tree if they are on a shortest path between a source and at least one destination of one of the logical multicasts that has been mapped to the physical multicast.

1 - 21 . (canceled) 
     
     
         22 . A method of forwarding multicast traffic by a node of link-state protocol controlled Ethernet network, the method comprising:
 receiving link-state information comprising community of interest membership information and nodal identifier information;   installing multicast forwarding state for a multicast address associated with a multicast tree, the multicast address comprising a nodal identifier and a community of interest identifier; and   forwarding packets carrying the multicast address as a destination address according to the installed forwarding state.   
     
     
         23 . The method of  claim 22 , comprising:
 computing shortest paths based on the received link-state information; and   determining the multicast forwarding state based at least in part on the computed shortest paths.   
     
     
         24 . The method of  claim 22 , wherein the multicast tree is a source-specific multicast tree. 
     
     
         25 . The method of  claim 24 , wherein the link-state protocol information uniquely associates the nodal identifier of the multicast address with a source node of the multicast tree. 
     
     
         26 . The method of  claim 22 , wherein the community of interest identifier of the multicast address is an IEEE 802.1ah service instance identifier (I-SID). 
     
     
         27 . The method of  claim 26 , wherein the link-state protocol information associates the community of interest identifier of the multicast address with a source node of the multicast tree. 
     
     
         28 . The method of  claim 27 , wherein the link-state protocol information associates the community of interest identifier of the multicast address with at least one other node on the multicast tree. 
     
     
         29 . The method of  claim 28 , wherein the link-state protocol information associates the community of interest identifier of the multicast address with all leaf nodes of the multicast tree. 
     
     
         30 . The method of  claim 22 , comprising forming the multicast address associated with the multicast tree by:
 using a nodal identifier of a source node of the multicast tree as the nodal identifier in the multicast address; and   using a community of interest identifier associated with the source node and at least one other node on the multicast tree as the community of interest identifier in the multicast address.   
     
     
         31 . The method of  claim 30 , wherein the source node and all leaf nodes of the multicast tree are members of a community of interest associated with the community of interest identifier of the multicast address. 
     
     
         32 . The method of  claim 22 , wherein:
 the nodal identifier of the multicast address identifies a source node of the multicast tree; and   the community of interest identifier of the multicast address is associated with the source node of the multicast tree and at least one other node on the multicast tree.   
     
     
         33 . The method of  claim 32 , wherein the source node and all leaf nodes of the multicast tree are members of a community of interest associated with the community of interest identifier of the multicast address. 
     
     
         34 . The method of  claim 22 , comprising:
 determining that the node is on the multicast tree prior to installing the multicast forwarding state for the multicast address associated with the multicast tree; and   discarding packets carrying multicast destination addresses associated with multicast trees that do not include the node.   
     
     
         35 . The method of  claim 22 , comprising:
 determining whether the node is on a multicast tree; and   installing multicast forwarding state for a multicast address associated with the multicast tree at the node only if the node is on the multicast tree.   
     
     
         36 . The method of  claim 22 , wherein the nodal identifier of the multicast address and the community of interest identifier of the multicast address taken together uniquely identify the multicast tree. 
     
     
         37 . A method of forwarding multicast traffic by a node of link-state protocol controlled Ethernet network, the method comprising:
 receiving link-state information comprising community of interest membership information and nodal identifier information;   determining that the node is on a multicast tree, the multicast tree having a source node, the source node having a nodal identifier, and a community of interest identifier being associated with the source node and at least one other node on the multicast tree;   forming a multicast address associated with the multicast tree from:   the nodal identifier of the source node of the multicast tree; and   the community of interest identifier associated with the source node and the at least one other node on the multicast tree;   installing multicast forwarding state for the multicast address associated with the multicast tree; and   forwarding packets carrying the multicast address as a destination address according to the installed forwarding state.   
     
     
         38 . The method of  claim 37 , comprising discarding packets carrying multicast destination addresses associated with multicast trees that do not include the node. 
     
     
         39 . The method of  claim 37 , comprising:
 computing shortest paths based on the received link-state information; and   determining that the node is on the multicast tree based at least in part on the computed shortest paths.   
     
     
         40 . The method of  claim 37 , wherein the community of interest identifier of the multicast address is an IEEE 802.1ah service instance identifier (I-SID). 
     
     
         41 . The method of  claim 37 , wherein the multicast tree comprises a source node and at least two leaf nodes.