[c-nsp] ASIC to switch port mapping

[Chris Evans]

They are closet switches. If you need bigger buffers get a platform meant
for heavier use such as the 4948.  There are other vendors with nice
offerings at a lower cost too so don't think Cisco is the only answer.
> Hi,
>
> On Fri, Sep 10, 2010 at 01:18:19PM -0400, Vincent Aniello wrote:
>> I am trying to solve a output drops on switch ports on which bandwidth
>> utilization does not seem to exceed the port speed. Seems like the
>> drops are due to the buffers filling up and dropping frames. I am under
>> the impression that each ASIC has their own buffer and if the buffer
>> fills on a particular ASIC all ports that share that ASIC will also drop
>> frames. If I know the switch interfaces associated with each ASIC I can
>> redistribute the connections on the switch to better balance the load.
>
> There's material in the c-nsp archives about the buffer size issue on the
> 2960, 3560 and related switches. Short answer: the buffers are so tiny
that
> Cisco doesn't even document the size anywhere. So as soon as you have
> microburst traffic with "more ingress ports than egress", you'll see drops
> (turn on QoS, cut the buffers into 4 even smaller queues, increase(!)
drops).
>
> Cisco does not think that this is a problem, and I have been told that the

> new generation 2960S and 3560E have the same size buffers.
>
> gert
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