Re: Question about QoS on C3750

The 3560s use Sasquatch strictly for egress queueing which have 2MB of
buffer each. You have 8192 buffer units, 256 Bytes each, and you also have
three pools and they are:

Supervisor, Common Pool and reserved pool (Which are configurable).

The big question is how these pools are configured and how many buffer units
are allocated to these pools?
560 Units for Supervisor which equates to 140KB. And if you subtract this
value from 8192, the remainder is divided between 24 (A 24 Port Box) X 4
(Queues per port).

I hope this helped.

On Mon, Jul 18, 2011 at 10:16 PM, Joe Astorino <joeastorino1982_at_gmail.com>wrote:

> That is actually a really good and tough question. When you are talking
> about interface buffers you are essentially just talking about memory that
> is allocated to store frames for a particular interface. I have never seen
> any numbers from Cisco that actually tell you what those buffers are in
> terms of bytes or anything else other than percentages. I guess I was
> assuming that 25% of the interface buffers would allow you to buffer 25% of
> the line rate, but I'm really not sure. Perhaps somebody can offer some
> more specific information on that topic.
>
>
>
> On Mon, Jul 18, 2011 at 11:02 PM, kawaii mak <kawaii00mak_at_gmail.com>
> wrote:
>
> > Dear Joe Astorino,
> >
> > Thanks. Means the percent of buffer is refer to the interface bandwidth
> ??
> >
> > Kawaii
> >
> > 2011/7/18 Joe Astorino <joeastorino1982_at_gmail.com>
> >
> >> I think you should be just fine with the default queueing mechanisms if
> >> you put your video traffic in the priority queue. The default buffers
> give
> >> you 25% of the interface buffer in the priority queue and 400% maximum
> >> (borrowing from the common pool). 25% of your Gig interface gives you
> >> 250Mb/s
> >>
> >> To see what you have allocated check out "show mls qos queue-set" and
> "sh
> >> mls qos interface <x/y> queueing"
> >>
> >> On Mon, Jul 18, 2011 at 4:10 AM, kawaii mak <kawaii00mak_at_gmail.com
> >wrote:
> >>
> >>> Dear Expert,
> >>>
> >>> I have a question about QoS apply on C3750 egree 1-GE uplink (Trunk)
> >>> interface with SRR queueing system. I need to allow the video traffic
> >>> (~200M) with high priority to use the GE uplink while the 1G uplink was
> >>> congested. How can I do that ?? The following is my question:
> >>>
> >>> Is it request to mark the cos of cs5 for the Video vlan traffic and set
> >>> the
> >>> cs5 with queue1 upder assigned queue-set as priority queue1 ??
> >>> Is the default queue set enough to priority the 200M streaming traffic
> go
> >>> first while the 1G link was congested ??
> >>> How to check the actually buffer bandwidth (e.g. bps) of the allocated
> >>> bandwidth for each queue ??
> >>> Or how to check the actually allocated bandwidth (e.g. in bps) for each
> >>> queue ??
> >>> For each queue, default configuration sets 400% as the maximum memory
> >>> before
> >>> dropped. How to check 400% is equal (in bps)??
> >>>
> >>> P'se help!!! Thank.
> >>>
> >>> Regards,
> >>> Kawaii
> >>>
> >>>
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> >>>
> >>>
> >>
> >>
> >> --
> >> Regards,
> >>
> >> Joe Astorino
> >> CCIE #24347
> >> Blog: http://astorinonetworks.com
> >>
> >> "He not busy being born is busy dying" - Dylan
> >>
> >>
> >
>
>
> --
> Regards,
>
> Joe Astorino
> CCIE #24347
> Blog: http://astorinonetworks.com
>
> "He not busy being born is busy dying" - Dylan
>
>
> Blogs and organic groups at http://www.ccie.net
>
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