[c-nsp] QoS support on Catalyst 6503

[sthaug at nethelp.no]

>    I have some basic questions regarding QoS implementation on a Cisco 
> 6503.
> 
>    My experience with policing on the 6509 from the 1999-2002 period was 
> that the policing wasn't as strict as what you'd expect from CAR 
> (typically a few extra Mbps of traffic "leaked" througH).  Cisco 
> informed me that this was due to the way that the equipment was 
> implemented -- i.e. it didn't have enough guts to police at a faster 
> rate, so there was a basic limit to what it could do.
> 
>    I have no experience with the 6503 - is it a different implementation 
> than the 6509?  Does it's QoS suck as much as the 6509s did then?  Is 
> it better now?  What about prioritization and queueing?

As far as I know, the 6503 behaves exactly the same as the 6509 in
this respect, for the simple reason that the same components are
used. As far as I recall the PFC is the component does the policing.
The Sup720 (PFC3/PFC3B etc) is more capable that the Sup2/PFC2 here,
for instance by supporting output policing (which the Sup2/PFC2 does
not).

Steinar Haug, Nethelp consulting, sthaug at nethelp.no