[c-nsp] N7k CoPP versus rate-limiters

[Phil Mayers]

On 20/03/12 20:53, Tóth András wrote:
> Hi Phil,
>
> There are certain exceptions for packets being forwarded which are not
> handled by CoPP, these are covered by the HW Rate Limiters.

Andras,

Thanks for the response. Unfortunately it didn't tell me anything I 
didn't already know ;o)

In fact, it appears to be largely cut&paste from the NX-OS docs, which I 
have read.

Perhaps I wasn't specific enough in my original email.

I'm looking for comprehensive documentation on what types of packets are 
considered to match the HW rate limiters, what types of packets match 
CoPP, and how the system acts when >1 match occurs.


This kind of behaviour is not well documented for Sup720, but if you dig 
through the Cisco site and archives of the list, you can find your info.

It is even LESS well documented for N7k as far as I can tell. The HW RL 
have uninformative names like "layer-3 control" and there is little or 
no documentation about how they interact, other than tantalising hints like:

"""
Layer 3 control, multicast direct-connect, and ARP request packets are 
controlled by the Layer 2 copy rate limiter. The first two types of 
packets are also controlled by Layer 3 rate limiters, and the last two 
types are also subject to control plane policing
"""

For example: which HW rate-limiters does an OSPF packet match, if any? 
In which order do these rate-limiters match, and is it before or after CoPP?

Or, the "receive" HW RL versus CoPP.

Or, the "layer-3 ttl" HW RL versus the "match exception ttl-failure", or 
again for "mtu".

Hope that explains things in more details.

Cheers,
Phil