Re: mls Qos

One other interesting issue is that turning on MLS QOS on a 650x/760x can
cause port channels to drop if you are crossing modules that aren't
identical. In a lab environment we had 1 member of the port channel in a
ten gig etherchannel on a 4 port card and one on a 8 port card. turning on
QOS disabled one of the members of the port channel due to the different QOS
treatment of the ten gig modules. We saw this in our lab environment so
there was no production impact.
Hope this helps,
Gregory Wendel
CCIE #20179

On Sun, Jul 26, 2009 at 10:13 PM, Ryan West <rwest_at_zyedge.com> wrote:

> I think the horse has been properly beaten. It's already a long thread, so
> if I'm repeating anything it won't be anything new :) The default behavior
> is that QoS is disabled, so as Evan said all traffic from any port can have
> any marking that it likes. This isn't the end of the world, but it requires
> that your voice routers crack the packets further to properly mark and then
> queue them, then you're looking at least three packet remarks to classify
> voice bearer, signaling and then remarking default to ... default.
>
> As Darby pointed out a long time ago (and sort of swayed away from), there
> is the SRND (I haven't read it a long time), but I'm pretty sure it says to
> mark at the endpoints and setup proper trust boundaries. So, while in the
> hands of the "wrong admin" someone might turn on QoS and then forget to
> trust ports / trunks / uplinks, Cisco has taken measures to prevent this
> with products like CNA and the basic built in web server. If CLI is scary,
> people have options like global macros and smartports (aka interface
> macros).
>
> Tracking down improper marking and trust boundaries should be completed way
> before implementing voice. I think it would negligent to have some setting
> up your QoS who doesn't have a clue.
>
> In short, I think you're right on Evan.
>
> -ryan
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Evan Weston
> Sent: Sunday, July 26, 2009 9:37 PM
> To: 'Darby Weaver'; 'CCIE Groupstudy'
> Subject: RE: mls Qos
>
> Basic CCNP principle here, I can't believe what Im reading.
>
> Set your trust boundary as close to the endpoints as possible. No mls qos =
> no trust boundary, you trust everything.
>
> Leaving mls qos turned off on an access switch because it will break things
> is just sloppy admin.
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Darby Weaver
> Sent: Monday, 27 July 2009 11:19 AM
> To: CCIE Groupstudy
> Subject: Re: mls Qos
>
> Again, let me refer you to the SRND by Cisco for further review of the
> subject:
>
> http://www.cisco.com/univercd/cc/td/doc/solution/esm/qossrnd.pdf
>
> A lot of classes explain it, but not everyone makes it that class and if
> they did let's face it QoS is a lot of material to cover in the the time
> usually given to it.
>
> Now if you actually have to work on a topic like video conferencing and
> video streaming there is a white paper I strongly recommend reading...
>
>
>
> http://www.cisco.com/en/US/solutions/collateral/ns340/ns394/ns158/ns280/net_
> design_guidance09186a00800d67f6.pdf
>
> http://www.cisco.com/en/US/docs/video/cuvc/design/guides/srnd/vidpref.html
>
>
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-- 
Gregory Wendel
Springfield VA, 22153
Blogs and organic groups at http://www.ccie.net