November 2006IETF TRILL WG1 TRILL Working Group draft-gai-perlman-trill-encap-00.txt as modified by Radia Ed Bowen, IBM Dinesh Dutt, Cisco Silvano Gai, Nuova Radia Perlman, Sun

November 2006IETF TRILL WG2 Proposed Shim Header Egress Rbridge AddressIngress Rbridge Address Reserved M Hop Limit 32 bits 9 1 6

November 2006IETF TRILL WG3 Encapsulation over Ethernet PT = TRILL Outer Source MAC Outer Destination MAC Outer Dest MAC Payload PT = IPv4 Inner Source MAC Inner Destination MAC Inner Dest MAC FCS Ingress Rbridge Address Reserved M Hop Limit Egress Rbridge Address

November 2006IETF TRILL WG4 Hop Limit 6-bit unsigned integer. This is decremented by 1 at each node that forwards the frame. The frame is discarded if Hop Limit is decremented to zero. –Need to define what happens on the egress RBridge This field was previously referred to as TTL (Time To Live). In IPv6 the IETF has replaced the concept of TTL with Hop Limit.

November 2006IETF TRILL WG5 Ingress/Egress Rbridge Addresses Both required for: –Conventional protocol design more future proof –IEEE 802.1au BCN in the CRED –Extended ACLs Similar to an RPF check –Policy-based forwarding –Troubleshooting, debugging, and tracing –Learning –Encoding other information for multicast

November 2006IETF TRILL WG6 How many bits for addresses 16 bits –I.e. 64K RBridges Forecast for largest layer 2 networks –100,000 stations, 800 switches 64K gives us a safety factor of 80 –Even assuming that all switches will be replaced by RBridges

November 2006IETF TRILL WG7 M bit M = 0 –The frame is a unicast –The “egress RBridge address” contains the egress “RBridge ID” M = 1 –The frame is a broadcast/multicast –The “egress RBridge” address contains the “Tree ID”

November 2006IETF TRILL WG8 Motivation for specifying the tree TRILL supports multipathing for unicast. For multicast TRILL currently uses IRT –all multicast traffic from an ingress RBridge uses the same links, i.e. no multipathing. By specifying the tree –Adds multipathing and load balancing support –Allows the ingress RBridge to select among a number of trees.

November 2006IETF TRILL WG9 Trees The Ingress RBridge –Can choose any tree as a local decision –Its decision is recorded in the “egress RBridge address” The core RBridges –Forward the frame according to the recorded value –No tree jumping –No consistent hashing required in core

November 2006IETF TRILL WG10 Limits on Djikstra computation For unicast each RBridge computes one Djikstra instance –independent of the number of RBridges IRT adds as many Djikstra computations as the number of RBridges –Not a scalable solution in large networks –Not scalable for more than hundreds of trees

November 2006IETF TRILL WG11 Let’s reduce the # of Trees Let’s define few trees that are used by all RBridges –number of Djikstra computations equal to number of trees used N trees rooted in N RBridge Configuration can specify: N (less than or equal to # of RBridges) Rbridge Root Priorities

November 2006IETF TRILL WG12 Other Open issues Broadcast storm prevention Optimization for point-to-point links Wiring Closet solution LIDs

November 2006IETF TRILL WG13 Conclusions These slides replace: draft-gai-perlman-trill-encap-00.txt Ingress/Egress Rbridge addresses Trees –Load balancing for multicast –Reduced number of trees Open issues –Need to be addressed