[c-nsp] BGP and decrease CPU usage

[Michael K. Smith - Adhost]

Are you having to reduce BGP usage because your processor is pegged all the time with BGP processes (scanner, etc.) or because it spikes?  The processor is supposed to spike while it's doing it's updates.  Here's a GSR's output while scanning.

CPU utilization for five seconds: 99%/0%; one minute: 19%; five minutes: 15%
 PID Runtime(ms)   Invoked      uSecs   5Sec   1Min   5Min TTY Process 
 200  2553083580  15050987     169631 96.00% 16.87% 12.84%   0 BGP Scanner      

If you're going to apply a .* deny, why have the peer at all?  You're not going to get any routes.  You might want to consider accepting a default-only from a provider.  This will certainly cut down on the amount of processor for scanning, although it will still hit 99% when it's running, would be my guess.

Mike

--
Michael K. Smith - CISSP, GSEC, GISP
Chief Technical Officer - Adhost Internet LLC mksmith at adhost.com
w: +1 (206) 404-9500 f: +1 (206) 404-9050
PGP: B49A DDF5 8611 27F3  08B9 84BB E61E 38C0 (Key ID: 0x9A96777D)


> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Robert Hass
> Sent: Monday, November 15, 2010 2:28 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] BGP and decrease CPU usage
> 
> Hi
> 
> I was wondering is disabling 'bgp nexthop trigger' will decrease a
> little CPU usage on router ? Eg.:
> 
> cisco(config)#router bgp 111
> cisco(config-router)#address-family ipv4
> cisco(config-router)#no bgp nexthop trigger enable
> 
> Router currently holds 3 full BGP feeds from external peers and nearly
> ony full from iBGP.
> 
> Question for Cisco engineers with deep inside IOS knowledge: What is
> most low CPU consuming way to filter all prefixes from neighbor ?
> a) as-path filter deny .*
> b) route-map XX deny 10
> c) some sort of deny ACL (ext: deny ip any any / or standard: deny
> any) or prefix-list ?
> d) different way ?
> 
> I'm gonna to do some tweaks inside BGP configuration for save some
> router CPU power.
> 
> Robert
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