[c-nsp] BGP scanner taking up CPU

[Rodney Dunn]

It would be interesting for someone to compare the
scanner CPU usage when they upgrade to 12.2(33)SRA that
has the fix for:

CSCef51906
BGP: reduce CPU impact of scanner

which is an internal enhancement we made to reduce the work
the scanner has to do.

Rodney

On Fri, Aug 11, 2006 at 02:56:20PM +0200, Marian Durkovic wrote:
> 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.  
> 
> --------------------------------------------------------------------------
> ----                                                                  ----
> ----   Marian Durkovic                       network  manager         ----
> ----                                                                  ----
> ----   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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