[c-nsp] CEF and multicast on a 3750

[Andriy Bilous]

Someone on IRC shared excellent slides about getting IPTV work as
expected. They might be worth to take a look at:

http://www.slideshare.net/brouer/challenges-and-experiences-with-iptv-from-a-network-point-of-view

On Tue, Jun 26, 2012 at 11:38 PM, John Neiberger <jneiberger at gmail.com> wrote:
> On Tue, Jun 26, 2012 at 2:48 PM, Saku Ytti <saku at ytti.fi> wrote:
>> On (2012-06-26 22:07 +0200), Gert Doering wrote:
>>
>>> Haaaahahaa... so the 3750 has the same issues the 2960 has - if you
>>> turn on "mls qos", the tiny buffers get reduced to tiny/4 buffers,
>>
>> Common misconception. Just turning 'mls qos' on makes situation worse for
>> microbursts, but tuning it correctly it behaves better than no 'mls qos'.
>> Unfortunately good documentations are not searchable via CCO.
>>
>> https://supportforums.cisco.com/docs/DOC-8093#_Toc191205672
>> --
>>  ++ytti
>
> In our case, around 99.99% of the traffic on that switch is multicast
> video that is all marked the same way. In that sort of situation, QoS
> isn't going to help and it adds additional latency because the
> scheduler still has to check all the queues. (At least that's what the
> SME from Cisco said.) Turning off mls qos re-enables FIFO and
> decreases latency by getting rid of the unnecessary scheduler.
>
> John
>
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