Per-Group ECMP for Multidestination Traffic in DCE/TRILL Networks

Abstract

Consistent with embodiments of the present disclosure, systems and methods are disclosed for providing per-group ECMP for multidestination traffic in a DCE/TRILL network. Embodiments enable per-group load balancing of multidestination traffic in DCE/L2MP networks by creating a new IS-IS PDU to convey the affinity of the parent node for a given multicast group. For broadcast and unknown unicast flooded traffic, the load balancing may be done on a per-vlan basis.

What is claimed is: 
     
         1 . A method comprising:
 obtaining a unicast ECMP graph;   identifying available paths for a plurality of network devices from the unicast ECMP graph;   identifying parents for each of the identified network devices;   obtaining group membership information for each of the identified network devices;   informing the identified parents of chosen group parent information derived from the group membership information;   flooding chosen group parent information via group membership LSP (“GM-LSP”); and   enforcing selection of group information through forwarding constructs.   
     
     
         2 . The method of  claim 1 , further comprising obtaining group membership information using local policy information via one of: IGMP or MLD. 
     
     
         3 . The method of  claim 1 , further comprising dynamically adjusting chosen group parent information upon notification of a change in the unicast ECMP graph. 
     
     
         4 . The method of  claim 1 , further comprising sending a GPS-PDU between each of the plurality of network devices and their respective associated parent network devices. 
     
     
         5 . The method of  claim 4 , further comprising each of the plurality of network devices selecting an associated parent network device to accept traffic for a designated group. 
     
     
         6 . The method of  claim 5 , further comprising masking the address associated with the designated group. 
     
     
         7 . The method of  claim 1 , further comprising ensuring that each of the plurality of network devices has only one associated parent network device for a given source switch. 
     
     
         8 . The method of  claim 7 , further comprising forwarding the only one associated parent network device information for a given source switch. 
     
     
         9 . A network device comprising:
 a processor configured to:
 obtain a unicast ECMP graph; 
 perform load balancing based on a hash packet associated with the unicast ECMP graph; 
 select a unicast path based on load balancing; and 
 determine per-group based on the unicast ECMP graph which of a plurality of parent switches can send traffic directed to each group such that a single parent switch exists for each source switch. 
   
     
     
         10 . The network device of  claim 9 , wherein the processor is further configured to add an outgoing interface to a tree associated with the determined parent switch. 
     
     
         11 . The network device of  claim 10 , wherein the processor is further configured to add a PDU extension to an IS-IS protocol. 
     
     
         12 . A method comprising:
 establishing a first PDU extension;   flooding information associated with the first PDU extension to a plurality of switches in a network, wherein each of the plurality of switches has interested multicast receivers for a first group; and   indicating via PDU information which of a plurality of parent switches should send traffic associated with a given multicast address.   
     
     
         13 . The method of  claim 12 , further comprising establishing an identifier that alerts switching devices that an enhanced protocol is employed. 
     
     
         14 . The method of  claim 13 , further comprising storing the identifier in space reserved for TRILL nicknames. 
     
     
         15 . The method of  claim 12 , further comprising computing an outgoing interface list at an intermediate parent switch. 
     
     
         16 . The method of  claim 15 , wherein the outgoing interface list only includes an ECMP path signaled by the PDU. 
     
     
         17 . The method of  claim 16 , further comprising modifying one of: an incoming interface check or a reverse path forwarding check. 
     
     
         18 . The method of  claim 17 , wherein the modification of one of: the incoming interface check or the reverse path forwarding check results in the check being done on a per-multicast group/per-source switch basis. 
     
     
         19 . The method of  claim 12 , further comprising receiving multicast packets for a multidestination group, wherein the multicast packets share an identical group address. 
     
     
         20 . The method of  claim 19 , further comprising selecting a parent switch for the identical group address based on VLAN information associated with the group.