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VLAN based Tree Selection for Multi-destination Frames

Document type: Expired Internet-Draft (individual)
Document stream: No stream defined
Last updated: 2013-07-29 (latest revision 2013-01-14)
Intended RFC status: Unknown
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IESG State: Expired
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found here:


TRILL uses the distribution trees to deliver multi-destination frames. Multiple trees can be used by an ingress RBridge for different flow based on VLAN and/or multicast group. Different ingress RBridges may choose different distribution trees for the same VLAN and/or multicast group traffic. Distribution trees are normally pruned based on VLAN. For any RBridge RBn, if RBn has downstream receivers of VLAN x in a distribution tree t, there will be an entry of (t, x, port list) in the multicast forwarding table on RBn. If there are n trees and m VLANs, the multicast forwarding table size on RBn is typically n*m entries. The value of m is up to 4096 and n is the total number of distribution trees in the campus. If fine grained labeling is implemented or finer granularity filtering such as VLAN plus L2/L3 multicast address is used for pruning, the multicast forwarding table size further increases dramatically. TRILL multicast forwarding table size is limited by hardware and L3 multicasting may share the same table with it in hardware implementations. Therefore multicast table entry is a precious resource. This document specifies a VLAN based tree selection mechanism to reduce the TRILL multicast forwarding table size on RBridge.


Li Yizhou <>
Hao Weiguo <>
Radia Perlman <>
Naveen Nimmu <>
Somnath Chatterjee <>
Sunny Rajagopalan <>

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid)