[c-nsp] nexus 7K COPP ARP traffic?

[Tóth András]

Hi Jeffrey,

All ARP requests which are broadcasts arriving in a vlan where an SVI
is up would be punted to CPU and throttled by CoPP and HW
rate-limiters. If there are no L3 interfaces, packets should not go to
CPU.

Perhaps they came from the management port, where CoPP is not applied.
It's difficult to tell post-mortem, we'd need to see which process was
using the CPU and confirm the type and source of packets hitting the
CPU with an inband SPAN capture or an ethanalyzer capture.

Best regards,
Andras


On Mon, Mar 26, 2012 at 5:54 PM, Jeffrey G. Fitzwater
<jfitz at princeton.edu> wrote:
>
> I am trying to understand if ALL ARP (requests ) packets that a nexus 7K sees, need to be punted to the CPU and therefor managed by COPP policies / rate-limits?
>
> Over the weekend we had a data loop that cooked the CPU and we are trying to understand what packets that were control plane processed, caused the CPU load.
>
> We currently have a Nexus 7k running 5.2.1, that only has L2 interfaces, other than the management VRF port.   I would think that the CPU would never have to process any ARP requests for non-management traffic since it does not have any L3 interfaces.
>
>
> My understanding is that other sites have had similar issues and changing the COPP profile stopped  the CPU form being saturated during this kind of event.
>
> The COPP profile can be ( lenient, moderate, strict ).
>
>
> Thanks in advance for any info on this issue.
>
>
>
> Jeff Fitzwater
> OIT Netwrok Systems
> Princeton University
>
>
>
>
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