nanog mailing list archives
Re: Using IPv6 with prefixes shorter than a /64 on a LAN
From: Mikael Abrahamsson <swmike () swm pp se>
Date: Tue, 1 Feb 2011 06:02:07 +0100 (CET)
On Mon, 31 Jan 2011, Per Carlson wrote:
Really? I've tried to duplicate the results in our lab, but I can't provoke any problems at those numbers. Is it the "other" multicast traffic that's interfering with ND?
It's a hold-queue problem. Normally IPv6 input is around 0.5% CPU on the RP, but due to IPv6 not being supported for SPD and this also seems to cause problems with IPv4 BGP traffic as well, the hold-queue (we raised it a lot) gets full and packets are tail-dropped from the hold-queue, and keepalives being lost.
This has been through a full analysis by TAC and their suggestion was to filter non-needed IPv6 multicast, and it completely removed the symptom. We haven't had any major BGP session flaps since.
When pounding the CPU with ~30 times more (5000pps) Neighbour solicitations and flapping 1000 BGP IPv4 prefixes (out of 51000) every 5 seconds, I get the following load (worst case):
We're getting many tens of thousands of prefixes from AMSIX and this peering router is in our BGP full mesh, so when peers go down, it's a lot of paths to recalculate (most of our IPv4 IBGP full mesh peers are in unique update groups for some reason on this router, that's also being analysed).
Even though IOS12000 seems fairly complete as an IPv6 core router, we've been running into more and more problems like this. Cisco has implemented a lot of features but not all and for IOS, they probably never will if I understand correctly. Guess XR is the way to go if one wants to keep it for a few more years...
-- Mikael Abrahamsson email: swmike () swm pp se
Current thread:
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN, (continued)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Owen DeLong (Jan 31)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Owen DeLong (Jan 25)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Ray Soucy (Jan 26)
- RE: Using IPv6 with prefixes shorter than a /64 on a LAN George Bonser (Jan 25)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Fernando Gont (Jan 25)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Matthew Petach (Jan 30)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Fernando Gont (Jan 30)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Matthew Petach (Jan 31)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Mikael Abrahamsson (Jan 30)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Per Carlson (Jan 31)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Mikael Abrahamsson (Jan 31)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Mark Andrews (Jan 24)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Owen DeLong (Jan 24)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN sthaug (Jan 24)
- Re: Using IPv6 with prefixes shorter than a /64 on a LAN Mark Smith (Jan 25)