[c-nsp] Monitoring CPU usage on a Sup720-3BXL (BGP)

[Richard A Steenbergen]

On Tue, Sep 01, 2009 at 02:10:22PM -0400, Drew Weaver wrote:
>                 Hey there,
> 
> We've probably all seen this issue before, with BGP scanner eating up
> a large amount of CPU time on a powerful supervisor/route processor,
> etc. My question is, how are you supposed to accurately monitor the
> performance/utilization of the system when this thing is pushing it up
> to 80% on a regular basis, alternatively, does anyone know if they're
> ever going to release a product that doesn't have this quirk? its been
> doing this since the days of the 7500 /w VIP2-50s (as far as I know).

BGP next-hop tracking helps, but doesn't completely remove the need for 
BGP scanner. I know SRB+ has it, not sure about SXH/SXI/etc or any other 
platforms.

http://www.cisco.com/en/US/docs/ios/iproute/configuration/guide/irp_bgp_adv_features.html#wp1056214

Of course this just opens the door for new obscure ways for things to
consume CPU and cause problems. The scheduler in newer IOS like SR is
certainly a lot better, so when something does spike it is less likely
to cause disruptions to the rest of the router. In theory the scheduler
from modular IOS is much better too, but this only comes into play if
the process you care about has actually been broken out and isn't
running under the big ios main process.

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)