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Simplified PBB-VPLS interworking with MMRP draft-allan-mmrp-for-mac-in-mac-00. Dave Allan, Nigel Bragg, Dinesh Mohan July 2008. Problem Statement. PBBN-VPLS interworking is different…. It is a VPN of VPNs Desire to isolate and interconnect active topologies with VPLS
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Simplified PBB-VPLS interworking with MMRP draft-allan-mmrp-for-mac-in-mac-00 Dave Allan, Nigel Bragg, Dinesh Mohan July 2008
Problem Statement • PBBN-VPLS interworking is different…. • It is a VPN of VPNs • Desire to isolate and interconnect active topologies with VPLS • vs. one large fully transparent overlay • Number of sites per PE approaching one • Number of sites per PBBN comparatively large • Desire to provide “per-service” multicast containment • Resilient and efficient interconnect is table stakes • Large number of services are aggregated onto any PBBN/VPLS interface • But are I-tagged
Objectives • Simplicity, simplicity, simplicity HOW???? • Peer at the B-component layer vs. I-component layer • Single pre-provisioned PW mesh for all services carried by the PBBN • Operational decoupling of service provisioning when VPLS used for PBBN transit • Multicast MAC filtering at ingress to PW mesh for efficiency • Elimination of requirement for “MAC-withdraw” messaging • Replace with some form of aggregated MAC invalidation signal/active topology change semaphore • Resilient interconnect • Including handling severing of a subtending MSTI domain • Symmetric forwarding
Observations • I-component awareness is not required by VPLS • C-MAC flooding and learning maps to well understood B-component multicast MAC addresses • Appropriate filtering of B-component multicast addresses is sufficient to isolate services • If I cannot learn about you and you cannot learn about me, we cannot communicate • Elimination of I-component awareness eliminates need for any signalling enhancements • Pushes I-component awareness back to the BEBs at the edge • If a single MSTI domain subtends an individual VPLS VSI, PW “active/standby” status can be used to communicate MSTI state inter MSTP domain and trigger the flush of tables and reset of filters • Aggregated form of “MAC withdraw” more akin to STP “topology change” BPDU • 802.1ak MMRP is sufficient to program MAC filtering
Operational Model 1. PBBN/VPLS locally selects active uplink 1. PBBN selects active uplink PBBN MSTI PBBN MSTI Standby Active Active Standby 2. LDP preferential forwarding status bit selects PW to tie together active uplinks (independent mode)
Operational Model 3. MMRP registrations for I-SID multicast MAC program filtering PBBN MSTI PBBN MSTI I-SID 100 I-SID 100 Well known multicast MACs 802.1ah OUI I-SID 22 bits 24 bits
Operational Model 4. Far end Change in active uplink signalled by change of active/standby status 6. Change from standby to active triggers generation of VPLS facing MMRP registration messages 6. Change from standby to active triggers generation of VPLS facing MMRP registration messages PBBN MSTI PBBN MSTI 5. Change from active to standby triggers flush of MACs mapped to that PW, and resets VPLS facing MMRP filtering
Going further, 802.1aq Shortest Path Backbone Bridging • This is a preliminary view • SPBB uses (S,G) trees, vs. (*,G) within a spanning tree • SPBB control plane can overlay VPLS • MMRP accommodates this with “full participant/application participant” registrations • Send/receive or receive only • Permits H&S style multicast VPLS Full Participant Application Participants
Summary • MMRP driven multicast filtering at the VPLS PEs eliminates need for I-component awareness • VPLS can be pre-provisioned and decoupled from PBBN operations • Substantial reduction of state at the VPLS-PEs • Significant adjunct to scalability • Single subtending PBBN MSTI per VPLS VSI permits preferential forwarding bit to be the synchronization mechanism for learning/flushing and MMRP • Implementations may co-locate some functions