[j-nsp] How to trace fpc/cfeb CPU usage?

Rafał Szarecki rszarecki at gmail.com
Fri Feb 16 18:10:11 EST 2007


Hi all,

FEB/CFEB CPU is responsible for delivery information between PFE (asics) and
RE.

If your m7i is doing packet sampling (netflow/jflow, or to file)? This is
one of very often reasons of hi CPU usage.

This CPU is also responsible for generate ICMP reports like e.g. "TTL
exceeded" or "No route to host". This can be another reason - too many
packets.

This CPU is also responsible to handle options in IPv4, e.g. if source
routing  is set. The best prectice is to disable forwarding of such packets.
You not need this for any resonable application - this is used by black hat
guys.

Is this Hi CPU load periodical? If this period is inline with some statistic
gathering (from outside via SNMP, or internaly to file. e.g. LDP stats
period)



2007/2/16, Joerg Staedele / Trusted Network GmbH <js at tnib.de>:
>
> Hi there,
>
> i still have a strange behaviour on our M7i. The CFEB load goes up to
> 20%, then goes down to <5% then up again and so on.
>
> I really have no idea what is causing this. We have several other
> routers  (M5/M10/M20) that all behave normal.
>
> The behaviour of the m7i is also seen in our smokeping that monitors all
> our routers. you can see that the m7i has higher loads and  responds
> "slower" more often than the others to icmp querys.
>
> So i just want to know what is causing the higher cpu on the cfeb but
> dont know how.
>
> What things are done in cpu on the cfeb? Maybe a list would give me a
> hint.
>
> Any ideas?
>
> Thanks in advance.
>
> Regards,
>
> Joerg
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> juniper-nsp mailing list juniper-nsp at puck.nether.net
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>



-- 
Rafał Szarecki JNCIE
+48602418971


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