[c-nsp] sup720 - is using 'mls rate-limit unicast cef receive' wise/recommended?

[Tim Stevenson]

The CEF receive rate limiter limits any traffic destined to any IP 
belonging to the RP (anything having a receive adj in the h/w). If you are 
NOT using copp, then it is ok and possibly advisable to use the CEF receive 
RL. If you ARE using copp, then it is advised NOT to use the CEF receive 
rate limiter.

Why? Because the h/w RLs override your copp policy. IOW, if a packet 
matches a configured rate limiter, it is NOT subjected to the copp policy. 
And of course, your whole copp policy will be full of your router's IP 
addresses.

You may want to take a look at this document, which discusses copp & the 
CPU RLs:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper0900aecd802ca5d6.shtml

HTH,
Tim

At 07:47 PM 6/23/2005, Rodney Dunn remarked:
>The mls rate-limit commands are hardware based rate limiters.
>
>CoPP orginally was just done in software but it's being pushed
>down to hardware to give closer to linerate dropping capability.
>
>SPD is is strictly a process level thing.
>
>Rodney
>
>On Thu, Jun 23, 2005 at 08:37:03PM -0500, Dale W. Carder wrote:
> >
> > On Jun 23, 2005, at 5:02 PM, Andrew Fort wrote:
> > > we found that 'mls rate-limit unicast cef receive' really helped the RP
> > ...
> > > My question is, do other people use this?
> > ...
> > >  is it just unnecessary to do this?).
> >
> > For the 6500/7600 TME's lurking,
> > How does this solution compare to control plane policing
> > and selective packet discard?
> >
> > Dale
> >
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Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Catalyst 6500
Cisco Systems, http://www.cisco.com
IP Phone: 408-526-6759
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