[c-nsp] 3560 buffering

[Peter Rathlev]

On Thu, 2009-10-15 at 09:18 +0100, Mateusz Blaszczyk wrote:
> > The reason I used queue 2 in the example is that the CPU apparantly
> > uses it so you can never allocate 0% for this queue. The "no QoS"
> > scenario is best achieved with one simple queue using all buffer
> > space. 
> 
> Isn't it better to give cos 6,7 (BPDUs, Routing) access to CPU queue
> and allocate all other cos values to separate queue?

I would agree, but I thought that would be more "implementing QoS"-like.
Since the switch actually seems to do exactly this even with "no mls
qos" it's probably a good idea to do. Otherwise "normal" traffic might
starve the CPU queue.

I can see that the default Auto-QoS maps (cos-map / dscp-map) use queue
2 for CoS 3, 6 and 7 (and DSCP 24-31, 48-55 and 56-63). I can't
immediately remember what CoS 3 is usually meant for; we currently use
it for "critical bulk traffic" but not for any special reason.

-- 
Peter