MPLS QoS Not Marking Nor Queueing

Unanswered Question
Jan 5th, 2009
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Hi All,

I have configured MPLS QoS in a 1841 PE router. F0/1, which is connected to CE, is marking the traffic; F0/0 is doing LLQ. But 'show policy-map int f0/0' shows packets matched but no marking is done for 'mpls experimental topmost X'. So I add 'set ip dscp' command. Packets are now marked with the dscp value, but still no queueing is happening in f0/0.

Here is the config:


class-map match-any mpls-5

match mpls experimental topmost 5

match ip dscp ef

class-map match-any mpls-3

match mpls experimental topmost 3

match ip dscp af31

class-map match-any iMission-Critical

description Interactive data:citrix sna telnet

match dscp af31

match access-group name Misn-critical

match ip dscp af31

class-map match-any iRealTime

description RealTime

match dscp ef

match dscp cs5

match dscp cs4

match access-group name Realtime

match ip dscp ef

match ip dscp cs5

match ip dscp cs4



policy-map TO-CORE

class mpls-5

priority 6000

class mpls-3

bandwidth 1000


class class-default

bandwidth 3000


policy-map 10-TO-CORE

class class-default

shape average 10000000

service-policy TO-CORE

policy-map FROM-CUSTOMER

class iRealTime

set mpls experimental topmost 5

set ip dscp ef

class iMission-Critical

set mpls experimental topmost 3

set ip dscp af31

class class-default

set mpls experimental topmost 0

set ip dscp default



'show' output is attached.

Thanks in advance.

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Overall Rating: 4 (1 ratings)
Giuseppe Larosa Tue, 01/06/2009 - 01:06
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Hello Larry,

some more information is needed.

this traffic belongs to a L3 MPLS VPN ?

If not the PHP= penultimate hop popping could cause traffic sent out f0/0 to be sent out without any label.

How long is the router chain ?

Two suggestions:

what happens if:

a) you use set mpls exp instead of set mpls exp topmost

b) on interface facing core try to apply the CBWFQ policy-map directly to the interface.

Hope to help


Chuan Liu Tue, 01/06/2009 - 11:51
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Hi Guiseppe,

Thanks for the response.

Yes, F0/1 is put in a VRF for a small site. F0/0 is facing the MPLS core. LLQ is applied directly to F0/0.

When I use 'set mpls exp' instead of 'set mpls exp topmost', I can see packets are marked on F0/1. But in the core facing policy, the 'topmost' key word cannot be removed. And, in the show output, the number of matching packets differs from the queueing number of packets as below: 130804 packets matched, but 50 are queued.


Service-policy : TO-CORE

Class-map: mpls-5 (match-any)

130804 packets, 26652361 bytes

5 minute offered rate 1000 bps, drop rate 0 bps

Match: mpls experimental topmost 5

130804 packets, 26652361 bytes

5 minute rate 1000 bps

Match: ip dscp ef (46)

0 packets, 0 bytes

5 minute rate 0 bps


Strict Priority

Output Queue: Conversation 264

Bandwidth 6000 (kbps) Burst 150000 (Bytes)

(pkts matched/bytes matched) 50/8829

(total drops/bytes drops) 0/0


Is this normal?


Giuseppe Larosa Tue, 01/06/2009 - 14:30
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Hello Larry,

no it is not normal

I would try with CBWFQ applied directly outbound the core facing interface

Hope to help



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