[c-nsp] 7200 DSCP-to-EXP Mapping

[Vitkovsky, Adam]

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:ar_djp at yahoo.com]
Sent: Monday, September 19, 2011 2:40 PM
To: Vitkovsky, Adam
Cc: cisco-nsp at puck.nether.net
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 <avitkovsky at emea.att.com> wrote:

From: Vitkovsky, Adam <avitkovsky at emea.att.com>
Subject: Re: [c-nsp] 7200 DSCP-to-EXP Mapping
To: "Oliver Boehmer (oboehmer)" <oboehmer at cisco.com>, "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
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: cisco-nsp-bounces at puck.nether.net</mc/compose?to=cisco-nsp-bounces at puck.nether.net> [mailto:cisco-nsp-bounces at puck.nether.net</mc/compose?to=cisco-nsp-bounces at puck.nether.net>] On Behalf Of Oliver Boehmer (oboehmer)
Sent: Monday, September 19, 2011 1:43 PM
To: cisco-nsp at puck.nether.net</mc/compose?to=cisco-nsp at puck.nether.net>
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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