[c-nsp] BGP scanner taking up CPU

[Marian Durkovic]

On Fri, Aug 11, 2006 at 02:35:27PM +0200, Oliver Boehmer (oboehmer) wrote:
> Joris de Mooij <> wrote on Friday, August 11, 2006 2:11 PM:
> 
> > Hi all,
> > 
> > We have a 6506 with Sup720-MSFC2 running IOS 12.2(18)SXD5. This router
> > holds the entire internet BGP table. Now we are suspecting the BGP
> > scanner process for causing temporary high CPU loads. Because this
> > process runs with a high priority, exec commands, pings and snmp seem
> > no to get through anymore. When using the vty exec, output seem to
> > stall for 1 to 3 seconds at least every minute.
> 
> BGP Scanner is a low-priority process (check "show proc <pid>"), it
> should not have that adverse effects. Maybe something else is going on.

Actually, those problems with BGP Scanner seem to be 6500-specific. 
During BGP Scanner runs the box stops processing the CPU-switched packets
and the SPD queue on the RP owerflows - thus the SNMP, telnet (but even
e.g. software switched multicast) packets get dropped and "SPD flushes" 
counters increment in jumps.

When SPD is disabled, the box runs much more smoothly, however manual
tuning of input hold-queues is needed for BGP etc.


	With kind regards,

		M.  

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----   Marian Durkovic                       network  manager         ----
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----   Slovak Technical University           Tel: +421 2 524 51 301   ----
----   Computer Centre, Nam. Slobody 17      Fax: +421 2 524 94 351   ----
----   812 43 Bratislava, Slovak Republic    E-mail/sip: md at bts.sk    ----
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