ASR 1004 QoS marking

Unanswered Question
Dec 18th, 2009

Dear team,

We have an Cisco ASR 1004 router. there is a traffic marking performed in LAN L3 switch. The Marked traffic is then forwarded to ASR 1004.

To our surprise, we have observed that the ASR 1004 is forwarding packets out VIA the WAN interfaces without any Marking.

We have confirmed with Special software that traffic entering the LAN interface of ASR 1004 is having proper Marking (DSCP marking on the header)...

But for the same traffic is the WAN out is analyzed, we could find that all traffic is traversing without any marking... It seems that ASR is removing all Marking from IP header.

Please help with your view in this problem

with regards,

Prasad. K

I have this problem too.
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Laurent Aubert Fri, 12/18/2009 - 07:46

Hi Prasad,

Are you using any encapsulation before sending the trafic to the WAN (IPSec,..)

Thanks

Laurent.

salleek Tue, 03/23/2010 - 10:49

Hi Prasad - I've been researching this a little. 

What is the interface to the ASR - is it a trunk or L2/L3 port?

I have a trunk port with ethernet sub-interfaces.  On the sub-interface I care about - I have a service-policy input on the interface that marks traffic w/ IP Prec according to how our provider requires them to place in the proper queue's across the MPLS backbone.  The applications I care about do not mark - and even if they did - I wouldn't trust them.  Anyway it looks something like this (very simple):

class-map match-any real-time

  match access-group name real-time

class-map match-any enterprise-apps

  match access-group name enterprise-apps

!

policy-map setTOS

class real-time

   set ip precedence 4

class enterprise-apps

   set ip precedence 1

class class-default

   set ip precedence 0

!

interface GigabitEthernet0/0/0.560

encapsulation dot1Q 560

ip vrf forwarding global

ip address 255.255.255.224

service-policy input setTOS

This works well.  But I also know that the ASR should honor marking as they come in.  That's where I think this doc / CCO link comes in

http://www.cisco.com/en/US/prod/collateral/routers/ps9343/solution_overview_c22-449961_ps9343_Product_Solution_Overview.html

I wonder if you need to add the:

aspeg-casr-01(config-subif)#plim qos input map cos enable

Then:

aspeg-casr-01(config-subif)#plim qos input map cos 5 queue strict-priority

Per your requirements.  That schedules packets with cos 5 ahead of the line for processing in the ESP...read the link above for theory of packet processing w/ QoS on the ASR.  You'd still need to apply an outbound service policy via MQC if you want to prioritize outbound traffic.

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