Re: performance impact on rate-limit

From: George Robbins (grr@shandakor.tharsis.com)
Date: Thu Aug 17 2000 - 14:40:04 EDT


CEF works fine it some situations, but is unstable in the more
complex 7500 multi-PA/multi-VIP/multi-IP environment, typically
it works fine for a while, then you find 50% of the packets to
some destination are being dropped (or routed to the wrong place)
and the damage is cumulative until you reboot or turn CEF off and
back on again. Customers don't appreciate this, and there's not
a big handle to make it easy to detect and/or debug, so the usual
response is to turn off CEF, try to manage the CPU loading and
then try the next release that comes out in the vain hope that just
maybe Cisco fixed something.

The other long-term Cisco bugaboo that's only getting worse as
time goes on is memory fragmentation in the ISP environment where
your're trying to run BGP & OSPF on 7500 core routers. You can
have ~15M-bytes of free memory, but no blocks larger than 100K
and then things start to fail right & left. This is killing the
RSP-1/2/7K based routers that have 128M memory limits, the 7200's
have a little more slack due to the smaller IOS images.

                                                George

> To: Brian Wallingford <brian@meganet.net>
> From: Paul Jacobs <paul@netpacq.com>
> Subject: Re: performance impact on rate-limit
> Cc: Cho Man Fai <mfcho@hknet.com>, cisco-nsp@puck.nether.net
> In-Reply-To: <Pine.LNX.4.10.10008162356170.19834-100000@cerise>
> References: <Pine.BSI.4.21.0008171127270.20759-100000@intranet.hknet.com>
> Old-X-Envelope-To: cisco-nsp
> Resent-From: jared@puck.nether.net
> Resent-Date: Thu, 17 Aug 2000 14:26:49 -0400
> Resent-To: cisco-nsp@puck.nether.net
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>
> At 08:59 PM 8/16/2000, Brian Wallingford wrote:
> >: What's the performance impact of running rate-limit with a long access
> >: list in a busy interface?
> >
> >Very little, if you've managed to find a rev that doesn't choke under CEF,
> >and supports other features you need.
> >
> >-brian
> What problems have you seen with CEF?
>
> CEF works great for us here!...
>
>
> Best regards,
> Paul Jacobs /Senior Network Eng.
> Commerce Service Provider (CSP)
> Internet Presence Provider (IPP)
> http://www.netpacq.com
> mailto:paul@netpacq.com
> Picture : http://netpacq.com/nis_about.htm



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