[c-nsp] ASR9000 MPLS QOS Issue

[adam vitkovsky]

I would not recommend using Uniform mode as it modifies Customer(CE)
markings
With Pipe mode the scheduling egress from MPLS cloud towards the CE is based
on MPLS EXP markings -that will allow you use only generic outbound policy 
With Short-Pipe mode the scheduling egress from MPLS cloud towards the CE is
based on CE markings -that will allow you to use granular outbound policy
profiles per customer contract
 
The practice is to classify, mark and condition the traffic ingress to MPLS
cloud on PE based on the contract policy profile
If you manage the CE you can classify, mark and condition the traffic on CE
(by conditioning I mean shaping, policing and congestion avoidance)
On the MPLS links you should base you PHB on MPLS EXP and you should not
need any conditioning -as the core link capacities should be sufficient 
Usually only couple of classes are used in the core like: Priority, Conform
and Un-conform



adam

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Saku Ytti
Sent: Wednesday, July 11, 2012 12:19 PM
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] ASR9000 MPLS QOS Issue

On (2012-07-11 18:06 +0800), Xu Hu wrote:

> Yes, you are right, now my big concern is that if one packet have one DSCP
value, then after transfer through the MPLS network (deploy the MPLS EXP QOS
in the MPLS network) the output packet will attach the same DSCP value or
not?

Both are supported. Uniform mode where it is DSCP -> EXP, EXP -> DSCP. And
Pipe mode where in ingress you set EXP was you wish and in egress you can
schedule based on EXP, without writing it in DSCP.

I.e. Pipe mode retains original DSCP, not mangling it, not necessarily even
using it. Uniform mode transports DSCP as EXP.

I personally would always do Pipe mode as Core QoS and Access QoS are two
different things.
In Pipe mode depending on platform, you store EXP in internal DSCP or copy
it via QoS config to 'qos-group' in MPSL2IP and then in IP egress, you
schedule based on qos-group value. ASR9k does support qos-group, so I would
suggest using them.

--
  ++ytti
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