[c-nsp] C2960G and output drops

[Gert Doering]

Hi,

On Fri, Oct 03, 2008 at 09:41:10AM +1000, Brad Henshaw wrote:
> Gert Doering wrote: 
> 
> > OK, I've done quite some testing, tuning "to the extreme"...
> > Queueset: 1
> > Queue     :       1       2       3       4
> > ----------------------------------------------
> > buffers   :       1       5      93       1
> > threshold1:     100     200    1600     100
> > threshold2:     100     200    2400     100
> > reserved  :      50      50      90      50
> > maximum   :     400     400    3200     400
> > 
> > (and all traffic is mapped to queue 3).
> 
> From the output you provided earlier, most of the traffic as short in
> the 'sh plat port-asic' output was on queue 3, which corresponds to
> queue 4 in the above queueset. I assume you changed the mapping? (just
> asking to be certain)

Yes.  Forced all into queue 3, to see whether using a different queue
might make any difference:

mls qos srr-queue output cos-map queue 3 threshold 1  0 1 4 5 6 7
mls qos queue-set output 1 threshold 3 1600 2400 90 3200
mls qos queue-set output 1 buffers 1 5 93 1


> > ...I can change the drop rate between "too high" and "catastrophic".
> > Without mls qos, it seems to just give the port *all* the buffers...
> 
> Bugger. I don't know whether setting up srr-queue limiting or shaping
> might impact the behaviour here, but I'm really clutching at straws.

I tried, and all it does is "make things worse".

> Have you logged a case with the TAC for this one?

Not yet.  (Our L2 switches usually don't come with a maintenance contract,
as we have such a huge lot of them that it's much cheaper to replace them
if hardware breaks).

Given the other comments received in this thread, I'm doubtful whether
TAC will help find a solution, though...

gert
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USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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