1 / 5

Advertising ECMP Routes in BGP

Advertising ECMP Routes in BGP. Joel Halpern Manav Bhatia Paul Jakma. 65 th IETF – Dallas, TX. Requirements for an ECMP algorithm. MUST be able to advertise individual BGP paths to other multipath capable peers.

alair
Download Presentation

Advertising ECMP Routes in BGP

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Advertising ECMP Routes in BGP Joel Halpern Manav Bhatia Paul Jakma 65th IETF – Dallas, TX

  2. Requirements for an ECMP algorithm • MUST be able to advertise individual BGP paths to other multipath capable peers. • MUST preserve maximum path information and should be regular expression friendly • Path length MUST be retained when advertising routes to non multipath capable peers

  3. ECMP Capability • Uses MULTIPLE_HOP Capability • Defines a new bit in the bitmask of flags +-------+---+---+---+---+---+---+------+----+ | Bit: | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +-------+---+---+---+---+---+---+------+----+ | flag: | R | R | R | R | R | R | ECMP | AE | +-------+---+---+---+---+---+---+------+----+

  4. How does this work within an AS? R1 10.0.0.0/8 AS_PATH: A B C NEXT_HOP: N2 AS 65530 10.0.0.0/8 AS_PATH: A B C MULTIPLE_HOP: N2 R3 RR 10.0.0.0/8 AS_PATH: X Y Z NEXT_HOP: N1 10.0.0.0/8 AS_PATH: X Y Z NEXT_HOP: N1 (BGP RIB) *>i 10.0.0.0/8 N2 A B C ? *>i 10.0.0.0/8 N1 X Y Z ? Assuming that R3 can reach N1 and N2 independently and not via the RR #sh ip route B 10.0.0.0 [170/0] via nexthop to the RR R2 #sh ip route B 10.0.0.0 [170/0] via N1 B 10.0.0.0 [170/0] via N1

  5. Advertising to an EBGP/non Multipath capable IBGP peer AS 61000 AS 65530 10.0.0.0/8 ORIGIN: INCOMPLETE AS_PATH: {65530} [A X] [B Y] [C Z] R3 R4 *>i 10.0.0.0/8 N2 A B C ? *>i 10.0.0.0/8 N1 X Y Z ?

More Related