[c-nsp] High processor utilization on c12008 4port STM-1 line card

Robert E. Seastrom rs at seastrom.com
Thu Aug 17 08:42:48 EDT 2006


A few things to think about:

1) Maybe you don't have more than 260 Mbps of traffic to move?  Are
you seeing packet loss?

2) what's the prognosis for getting more bandwidth?  you're running
kind of hot...

3) Those cards are Engine 0 cards and pretty anemic.  You could turn
off the QoS stuff and see if things get better.

4) It's packets/second that really thrashes these (and most
software-based) cards.  How many pps are you running?

5) Those cards are fairly cheap on the secondary market (like, under
$500 apiece if I remember right).  You might want to consider
splitting your traffic onto two cards on both ends instead of two
ports on one card and see how much your CPU situation improves.

                                        ---Rob

Primoz Jeroncic <jp at softnet.si> writes:

> Hi everyone
>
> We have few c12008 and between two of them we have 2x STM-1 links.
> Based on my MRTG, link payload doesn't go over 130Mbps, even though on
> SONET its suppose to go all the way to 150Mbps (I might be wrong about
> this, but I think I'm not). This means we get only about 260Mbps instead
> of 300Mbps (we run OSPF for load balancing on those two links). After
> a bit of research, I found out that line card (on 4 port SONET STM-1 card)
> processor utilization is somewhere around 80% or even higher, while route
> processor utilization is around 10%.
>
> Now I have question if there's any way to get this thing down, since
> I have feeling to high utilization on line card's processor is reason
> why I can't get payload higher. Would more packet memory help reducing
> processor utilization?
>
> Current hardware config is following:
> - c12008 with GRP-B route processor and 512MB memory
> - 4 port SONET OC-3c/STM-1 line card with 256MB processor memory, 64MB
> TX Packet Memory and 64MB RX Packet Memory.
> - few additional line cards (8x FE card and 1x GE card)
>
> PS: In case if it matters... I do have some rate limiting configured on
> POS interfaces.
>
> Thanks for any help.
>
> Have fun,
> Primoz Jeroncic
> Support - IP Connectivity & Routing
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