Re: MLS QOS: 3560 vs 3550

Jack,
i think i have seen this before, even with the 3560. try this:

   - on the 3550, issue the command :"sho mls qos". based on your config so
   far, it should display something like:
      - QoS is enabled (assuming you did issue "mls qos" prior)
      - QoS ip packet dscp rewrite is enabled (this is by default)

the 2 bullets above mean that once you enable Qos, ,any packet traversing
the switch will be rewritten to dscp=0. so all yo need to do to achieve your
results is to just disable the global dscp rewriting, and the global command
for that is "NO mls qos rewrite ip dscp". if your 3550 supports this
command, then you should be golden. let us know what happens

Jep.

On Fri, Jan 22, 2010 at 11:54 AM, Mark Cairns <m.a.cairns_at_gmail.com> wrote:

> Are you trying to trust DSCP on the interface or are you trusting DSCP
> within the class used to define traffic for your policy? Sorry I don't have
> a 3550 in front of me. I believe you can have mls qos trust dscp on the
> interface or "trust dscp" in your class. Try the second one.
>
> Mark
> #17755, Security
>
> On Thu, Jan 21, 2010 at 12:23 PM, Jack Router <pan.router_at_gmail.com>
> wrote:
>
> > Responded too quickly.
> > "mls qos trust dscp" and "service-policy input TST" cannot co-exist on
> the
> > same interface. When one command is entered the other command is
> > automatically removed.
> >
> >
> > -----Original Message-----
> > From: Jack Router [mailto:pan.router_at_gmail.com]
> > Sent: 21-Jan-10 11:39
> > To: ron.wilkerson_at_gmail.com; ccielab_at_groupstudy.com
> > Subject: RE: MLS QOS: 3560 vs 3550
> >
> > Yes there is one and it works. Thanks.
> >
> > -----Original Message-----
> > From: ron.wilkerson_at_gmail.com [mailto:ron.wilkerson_at_gmail.com]
> > Sent: 21-Jan-10 11:29
> > To: Jack Router; ccielab_at_groupstudy.com
> > Subject: Re: MLS QOS: 3560 vs 3550
> >
> > Isn't there a trust dscp command on the 3550?
> > -----Original Message-----
> > From: "Jack Router" <pan.router_at_gmail.com>
> > Date: Thu, 21 Jan 2010 11:05:03
> > To: <ccielab_at_groupstudy.com>
> > Subject: MLS QOS: 3560 vs 3550
> >
> > Hello,
> >
> > I am testing policing. Here is diagram:
> >
> > R1--\
> > 3560(f0/19)----trunk----(f0/19)3550(f0/3)-----R3
> > R2--/
> >
> >
> > I am policing traffic from R1,R2 to R3
> > R1 sends packets marked DSCP 10
> > R2 sends packets marked DSCP 20
> > Policy map is applied on 3550 int f0/19:
> >
> > Policing seems to work because I can see ping drops on R1 or R2 as soon
> as
> > service policy is applied on 3550, int f0/19.
> > My problem is that 3550 rewrites all dscps to 0 as soon as mls qos is
> > enabled. On 3560 I can disable dscp rewrites with command "no mls qos
> > rewrite ip dscp" but on 3550 there is no such command.
> >
> > Is there a way not to rewrite DSCPs on 3550 so R3 will receive packets as
> > marked by R1 and R2?
> >
> > I know that there is no 3550 on the lab anymore but just want to
> understand
> > how
> > this works...
> >
> > Thanks,
> >
> >
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Received on Sun Jan 24 2010 - 13:59:15 ART