PIM ECMP Assert draft-hou-pim-ecmp-00 IETF 80, Prague

Agenda Overview Use Cases Design Consideration Packet Format Open Items Questions for the Working Group IETF 80draft-hou-pim-ecmp-001

PIM ECMP Assert Overview Existing ECMP RPF selection is driven by downstream, using either largest IP address or hash. –Lack of administrative choice on path selection –No flexibility. PIM ECMP Assert is proposed to improve control of RPF path selection. –Initiated by upstream routers (similar to Assert) –Used to choose a path based on administrative choice. IETF 80draft-hou-pim-ecmp-002

Use Case 1 IETF 80draft-hou-pim-ecmp-003 ABCD sources receivers RPF is Red/A RPF is Blue/A or Blue/B

Analysis On Case 1 Different routing policy –E.g, A/B and C/D are connected via BGP –C and D may have different number of paths Different hash algorithm –C runs source based hash while D runs group based hash Other implementation specific factors –Available paths are not sorted the same on C/D IETF 80draft-hou-pim-ecmp-004

Use Case 2 IETF 80draft-hou-pim-ecmp-005 ABCD sources receivers 5.RPF is Red/A 3.RPF is Blue/A 1.RPF is Red/A 2. Link Down 4. Link Up

Design Consideration Minimize control traffic in steady state Minimize unnecessary traffic disruption Reuse existing mechanism IETF 80draft-hou-pim-ecmp-006

Packet Format A0A1A2A3A4A5A6A7A8A9B0B1B2B3B4B5B6B7B8B9C0C1C2C3C4C5C6C7C8C9D0D | PIM Ver | Type | Reserved | Checksum | | Group Address (Encoded-Group format) | | Source Address (Encoded-Unicast format) | | Neighbor Address | | | Interface ID | | | Preference | | Metric … | | ….. Metric … | | IETF 80draft-hou-pim-ecmp-007

Open Items PIM Hello Options IETF 80draft-hou-pim-ecmp-008 ECMP Assert Hello Option | Type = TBD | Length = 0 | Normalized Metric ? Interface ID Insertion

Questions For The WG Interest? IETF 80draft-hou-pim-ecmp-009