QoS configuration scenario over an MPLS backbone

Unanswered Question
Feb 8th, 2007

Hi All,

I would like to discuss QoS configuration scenario over an MPLS backbone (Frame Mode MPLS over ATM Internetworking backbone using BPXs) for a provider to provide the MPLS VPN customer an appropriate QoS for their Voice traffic, my initial design is as follows:

CE-1 <-> PE-1 <-> P-1 <-> P-2 <-> PE-2 <-> CE-2



Classification and Marking.(Egress)

LFI (MLPPP over FR) (Egress)

WRED (For class-default) (Egress)

FRTS (Egress)

LLQ (Egress)



Remarking with MPLS Exp bits (Ingress from CE-1 to be used Egress to P-1, and then further on P-routers)

LLQ (on the egress facing CE-1 and P-1)

LFI (on the egress facing CE)

WRED (for class-default)

Policing (not CB-Policing, we shall rely on the ATM-PVC paramters)



LLQ (Egress facing both PE and P)

WRED (class-default)

First of all, i need comments on this design. Second i've a couple of questions:

1. since the P router won't be aware about either the DSCP or the IPP how will WRED work on it ?

2. How will i configure the LLQ between the PE(s) and the P(s), will i have to calculate the aggregate estimate required bw and apply it in the LLQ ?

thanks in advance,


I have this problem too.
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ahmednaas Fri, 02/09/2007 - 09:25


I can't answer your questions but I'd like to draw your attention to the following cisco press book I came across recently. It looks like it might have some useful info for your topic, especially chapter 5 (Backbone Infrastructure):

QoS for IP/MPLS Networks

By Santiago Alvarez


Publisher: Cisco Press

Pub Date: June 02, 2006

Print ISBN-10: 1-58705-233-4

Print ISBN-13: 978-1-58705-233-0

Pages: 336


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