[c-nsp] QoS Order of Operation in an MPLS environment

[Yasser Aly]

Oliver,

  Thanx for your reply.

Here is what I was trying to do and need your confirmation to solidify my
understanding.

MQC is applied at the PE router on the sub-interface facing CE.

Policing is applied for FTP class such that conformed packets will be tagged
with Prec 3 and transmitted, exceeded packets should be transmitted with
Prec 0.

Confusing comes from whether I need to set prec 3 and 0 as the action in the
police statement , or to set the mpls topmost 3 and 0 as the action -
confused when Prec are converted to mpls EXP -.

Below is the sample of the in-PE policy applied at the PE router.


========
policy-map in-PE
  class ftp
   police 102000 12750 25500 conform-action set-prec-transmit 3
exceed-action set-prec-transmit 0 class class-default
=========

The in-PE service policy is applied on the PE Sub-interface facing the
customer.

I have another question: What is the difference between set MPLS topmost and
Set MPLS imposition ?


Thanx in advance.
Yasser 

-----Original Message-----
From: Oliver Boehmer (oboehmer) [mailto:oboehmer at cisco.com] 
Sent: Tuesday, December 28, 2004 11:51 AM
To: Yasser Aly; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] QoS Order of Operation in an MPLS environment

Yasser,

>   I would like to know what is the order of operation for QoS inside a
> PE-router.
> 
> For the incoming packets from CE to PE router, inside the PE, will the
> packet tagged with the MPLS EXP once entered the VRF, or I will match
> and set ip prec values and PE will automatically translate it to the
> MPLS world inside the Provider core network.

On the VRF interface, you will match on the IP packet (i.e. no label).
By default, when we push labels to send this packet over the MPLS cloud,
the first three bits of the DSCP value is copied into all label's EXP
bits. If you want to change the MPLS EXP bits, you would do so within
the ingress policy-map.

> Any links elaborating this are highly appreciated.

take a look at http://www.cisco.com/warp/public/105/diffserv_tunnel.html
which gives an overview of the various QoS modes (uniform, pipe,
short-pipe) in an MPLS network.

	oli