[nsp] BGP4 and high Ping Times

[Oliver Boehmer (oboehmer)]

Lukas,

you can't do anything about the problem with the high latency when
pinging to the box itself.
Latency *through* the box can only be addressed with a faster CPU and/or
a distributed platform like the 7500 or GSR where the RP-CPU is not
involved in switching at all (when you use dCEF).

turning off CEF shouldn't help at all, it actually worsens the situation
as you will then use cache-based "Fast Switching" where the first packet
of a flow is processed by the "IP Input" process to create a cache entry
(subsequent packets are interrupt-switched using this cache entry). So
unless you run very low on memory, turning on CEF is almost always a
good idea.

	oli


> -----Original Message-----
> From: Lukas Krattiger [mailto:luk at everyware.ch] 
> Sent: Donnerstag, 30. Januar 2003 19:29
> To: cisco-nsp at puck.nether.net
> Subject: RE: [nsp] BGP4 and high Ping Times
> 
> 
> Well, I know that icmp has low priority, but how can I tweak it ? 
> CEF is disabled and with 12 of 15 Peers we do have a 
> PeerGroup, the rest are
> upstreams with specific rules. The thing with drpooing routes and not
> receiving full routes is a little bit difficult for an ISP so ...
> ... What do you guys recommend to tweak this box, any ideas other then
> disabling CEF ? :-)
> 
> Thanks
> -Lukas
> 
> 
> -----Original Message-----
> From: Stephen J. Wilcox [mailto:steve at telecomplete.co.uk] 
> Sent: Donnerstag, 30. Januar 2003 19:00
> To: Lukas Krattiger
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [nsp] BGP4 and high Ping Times
> 
> 
> Yes, you get this when the BGP scanner runs which is once per 
> minute, as the
> 7206 is a single processor this means whilst its churning 
> 250000 routes your
> packet latency goes up.
> 
> Try tweaking scheduler for a quick fix, if you dont need full 
> BGP tables try
> dropping some routes. Failing that its a bigger router...
> 
> (I assume you have got the basic stuff like cef running and 
> if you have many
> peers you have groups configured)
> 
> Steve
> 
> On Thu, 30 Jan 2003, Lukas Krattiger wrote:
> 
> > Greetings,
> > 
> > I'm wondering if some other people have the same issue with a cisco 
> > 7206VXR and BGP4. Our current Core-Router is a 7206VXR 
> (NPE300) with 
> > E3 and T3 cards, we are running IOS 12.1(14) and there is 
> the max of 
> > memory inside.
> > >From our Upstream-Providers (2 sometimes 3) we receive full routes.
> > The thing I don't understand is, why are we getting always 
> this high 
> > ping times every minute (maybe while we are receiving the 
> updates, I 
> > think so), is there a workaround to solve this issue or is 
> it just "as 
> > is" ?
> > 
> > Thanks for any reply
> > 
> > -Lukas
> > 
> > 
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> > 
> 
> 
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