Yes please during the swap operation the exp value of the incoming label is 
automatically used with the outgoing label
However during the pop operation the incoming label and it's exp value is lost 
and packet is dispatched with whatever remaining labels in the stack

So either you make sure that at the ingress PE -during the label imposition the 
exp value has been set accordingly on all the labels in the stack (usually 
NH-label and VPN-label)
-this way even though the topmost label and it's exp marking is lost during the 
POP operation
 the remaining label carries the same exp value as the top most one  -so you 
can use it to schedule the packet accordingly

Or on each penultimate hop node you manually copy the exp value of the top-most 
label that is going to be discarded during the POP operation and use it to set 
the newly exposed label's exp value


adam

________________________________
From: ar [mailto:[email protected]]
Sent: Monday, September 19, 2011 2:40 PM
To: Vitkovsky, Adam
Cc: [email protected]
Subject: Re: [c-nsp] 7200 DSCP-to-EXP Mapping

I believe as the packet travels the MPLS domain, same EXP bits are applied as 
they swap top labels..this means I can always match on the same exp bit as it 
was mapped at the ingress PE. Do I still need the qos-groups in this case?



--- On Mon, 9/19/11, Vitkovsky, Adam <[email protected]> wrote:

From: Vitkovsky, Adam <[email protected]>
Subject: Re: [c-nsp] 7200 DSCP-to-EXP Mapping
To: "Oliver Boehmer (oboehmer)" <[email protected]>, 
"[email protected]" <[email protected]>
Date: Monday, September 19, 2011, 8:13 PM
Speaking of pipe modes :)

I also failed to use the pipe mode with 12.2.33 SR codes
As I was not able to use the qos-groups to keep track of the EXP value on the 
egress PE
So on 7200s I pretty much got stuck with a short pipe mode and "set mpls-exp 
imposition" at the ingress PE

adam
-----Original Message-----
From: 
[email protected]</mc/[email protected]>
 
[mailto:[email protected]</mc/[email protected]>]
 On Behalf Of Oliver Boehmer (oboehmer)
Sent: Monday, September 19, 2011 1:43 PM
To: [email protected]</mc/[email protected]>
Subject: Re: [c-nsp] 7200 DSCP-to-EXP Mapping


> >
> > > I don't think there is in alternative to "set dscp
> > > default" on ingress policy-maps to effectively remark
> > > ingress traffic on an edge-LSR device.
> >
> > Not sure what you mean - as in you don't think we can mark
> > anything other than 'default' on ingress?
>
> 'course not, sorry.. I meant to replace "default" by "<value>" before
> sending, but forgot :-|

and before someone argues: the above is obviously not relevant when
using pipe/short-pipe mode, then you do NOT want to touch the ingress
DSCP at all...

    oli


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