On 10/25/2011 05:21 PM, Brad Fleming wrote:
Are there any tricks to auto-summarize the contents of a RIB where the
tributary routes are not originated locally?
Example:
Input routes:
prefix: 1.0.0.0/16, next-hop: 5.5.5.5
prefix: 1.0.1.0/16, next-hop: 5.5.5.5
prefix: 1.0.2.0/16, next-hop: 4.4.4.4
prefix: 1.0.3.0/16, next-hop: 5.5.5.5
Consolidated, Installed routes:
prefix: 1.0.0.0/14, next-hop: 5.5.5.5
prefix: 1.0.2.0/16, next-hop: 4.4.4.4
Basically a way to consolidate total number of prefixes entering the FIB.
This (aggregate routes on next-hop) comes up now and again, and the idea
seems to be controversial for some people. Various criticisms are cited
- unpredictability (a single route change could result in a large jump
in FIB use), performance implications, and fairly limited improvement
(the thread cited below reckons 30% mean, 10% worst case, 45% best case,
depending on connectivity topology)
Specifically, it's been discussed on the cisco-nsp mailing list, where
Cisco employees have said "we tried it, it's not that great, we're not
convinced" (although this was a while back).
Personally I'm not sure I'm convinced; it seems to me that it ought not
to be hard, and can hardly be worse than what happens when you overflow
the TCAM. But it's not a new, or uncontroversial, idea AIUI. See e.g.
http://puck.nether.net/pipermail/cisco-nsp/2007-March/039192.html
Cheers,
Phil
_______________________________________________
juniper-nsp mailing list juniper-nsp@puck.nether.net
https://puck.nether.net/mailman/listinfo/juniper-nsp
