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OSPF Hybrid Broadcast and P2MP Interface Type. draft-nsheth-ospf-hybrid-bcast-and-p2mp-01.txt 79 th IETF, Beijing Nischal Sheth Lili Wang Jeffrey Zhang. Problem Statement. Broadcast Network but with different metrics between different neighbors
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OSPF Hybrid Broadcast and P2MP Interface Type draft-nsheth-ospf-hybrid-bcast-and-p2mp-01.txt 79th IETF, Beijing Nischal Sheth Lili Wang Jeffrey Zhang
Problem Statement Broadcast Network but with different metrics between different neighbors Wireless broadcast network where some stations may have less-optimal placement Wired Ethernet where routers have different interface speeds Want to take advantage of the broadcast property Neighbor discovery & maintenance via multicast hello Adjacencies with DR/BDR only DB Synchronization, flooding via DR/BDR 8 R1 R2 15 12 8 10 5 R3 R4
Solution: Broadcast-p2mp hybrid interface • Treat as broadcast for: • Hello, adjacency, DB synchronization and flooding • Treat as p2mp for LSAs: • Details in section 3.6 • No Network LSA • Individual p2p links in Router LSA • Metrics can be either statically configured per-nbr, or dynamically learned if the underlying network supports it • Treat as p2mp for nexthop calculation
Special Considerations • Graceful Restart • Some straightforward additional considerations in section 3.8 • Compatibility • All routers connected by the hybrid interface need to support it • Otherwise • No traffic traversing certain pairs of routers • No persistent traffic loops or blackhole, though • Could use Link Local Signaling to signal the hybrid support and prevent adjacency from forming if there is inconsistency • Could use LLS to signal local interface speed for others to figure out metrics automatically • if speed is the only factor leading to per-nbr metrics • Scalability • O(N^2) links (comparable with p2mp) vs. O(N) (with broadcast)
Next Step? • Same concept could be used for TE • Do we care about NBMA-p2mp-hybrid? • Saves on adjacencies & DB sync/flooding • Not on hello • WG work item -> proposed standard ? • Individual submission for Informational/BCP RFC?