From: Pavel Bykov (slidersv@gmail.com)
Date: Sat Oct 04 2008 - 08:00:21 ART
Hello Ali.
Because "mls qos cos 1" assigns a default cos value to a port, it does not
mean that the value will be written to a frame. Default in this case means a
frame without any tag (i.e. access port). But when the packet has cos/dscp
value, and we are not trusting it, we want to overrride it with our special
value - cos 1 in this example.
Regards,
On Sat, Oct 4, 2008 at 8:12 AM, Ali Mousawi <mousawi.ali@gmail.com> wrote:
> Hello Huan,
> Why do we need "mls qos cos override"? Is'nt mls qos cos 1 enough? I am
> confused with Cat QoS I dnt like this topic
>
> On Fri, Oct 3, 2008 at 8:07 PM, Huan Pham <pnhuan@yahoo.com> wrote:
>
> > Hi,
> >
> > How about this simple solution, which overides the CoS values for ALL
> > packets arriving from R1, e.g.
> >
> > SW1#
> >
> > mls qos
> >
> > interface FastEthernet0/1
> > description == to R1
> > switchport trunk encapsulation dot1q
> > switchport mode trunk
> > mls qos cos 1
> > mls qos cos override
> >
> > If you want to selectively change only packets with CoS5 to CoS1, without
> > using policy-map (assumming that there're traffic with other CoS values
> > arriving to SW1 from R1), we have to do it indirectly via COS-DSCP map. I
> > believe your solution is the good example for this task. I haven't come
> up
> > with another one yet.
> >
> > Regards,
> >
> > Huan
> >
> >
> > --- On Sat, 10/4/08, ZZ <zurabz@gmail.com> wrote:
> >
> > > From: ZZ <zurabz@gmail.com>
> > > Subject: Re: QOS on 3560
> > > To: "Cisco certification" <ccielab@groupstudy.com>
> > > Date: Saturday, October 4, 2008, 6:12 AM
> > > and forgot one more thing:
> > >
> > > No config allowed on R2 and No service-policy on SW1 &
> > > SW2
> > >
> > > On Fri, Oct 3, 2008 at 4:05 PM, ZZ <zurabz@gmail.com>
> > > wrote:
> > >
> > > > Hi Experts,
> > > >
> > > > I'm practicing QOS stuffs in lab and got a
> > > question.
> > > >
> > > > Here is the topology:
> > > >
> > > > R1<->SW1<->SW2<->R2
> > > >
> > > > there is a trunk links between SW1 gig1/0/33 & SW2
> > > gig1/0/33, SW1 gig1/0/48
> > > > & R1 f0/0, SW2 gig 1/0/48& R2 f4/0
> > > >
> > > > I'm marking all frames on R1 with COS5.
> > > >
> > > > Need to see this frames as COS1 on R2. No config
> > > allowed on R2
> > > >
> > > >
> > > > R1
> > > > f0/0.12
> > > > encapsulation dot1q 12
> > > > ip add 1.1.12.1 255.255.255.0
> > > > service-policy output SETCOS5
> > > >
> > > > R1#sh policy-map SETCOS5
> > > > Policy Map SETCOS5
> > > > Class COS
> > > > set cos 5
> > > >
> > > > R1#sh class-map COS
> > > > Class Map match-all COS (id 3)
> > > > Match any
> > > >
> > > >
> > > > My solution is
> > > >
> > > > SW1
> > > >
> > > > mls qos map cos-dscp 0 8 16 24 32 37 48 56
> > > > int gig 1/0/48
> > > > mls qos trust cos
> > > >
> > > > -----------------
> > > > SW2
> > > > int gig 1/0/33
> > > > mls qos trust dscp
> > > >
> > > > mls qos map dscp-cos 37 to 1
> > > >
> > > > #######
> > > >
> > > > The config is working fine.
> > > > My question is:
> > > > Is there any other solution?
> > > >
> > > >
> > > > Thanks,
> > > > ZZ
> > >
> > >
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-- Pavel Bykov ------------------------------------------------- Stop the braindumps! http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
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