MPLS QoS with Uniform tunnel mode

[ty.chan007]

Hi, I am trying to test all mode of MPLS QoS tunnle mode like uniform,etc.

My diagram is as below:

CE01 --access--> ME4900 --trunk--> PE01 --ldp--> P01 --ldp--> P02 --ldp--> PE02 --access--> CE02

All traffic from CE01 are marked with DSCP AF31 an send to PE01. But PE01 can not see packet with AF31.

On ME4900, i just config access port and trunk port only. Nothing else were config on ME4900.

What should be the problem? or Does ME4900 reset DSCP value to 0 by default? if yes, how to fix it?

[ty.chan007]

Hi Varma,

Yes, it works if I just use "set mpls exp imposition 4". Is that mean EXP of both labels are set both VPN label and SP label if I use "imposition"? if i use "topmost", EXP is only set on SP label?

Back you to confirmation, EXP is not copied to IPP by default on PE egress. So, "Cisco QoS SRND" doc says something that is not right

Regards,

chanty

[Vaibhava Varma]

Hi Chanty

From my understanding setting the mpls exp topmost would work towards core as already there is a labelled packet enetring into core but when we set the same on the ingress interface towards CE then there is no label present at all and hence it does not works..At the ingress interface there is an IP2MPLS Transition and a label is being imposed and hence the imposition keyword works..

Regarding the EXP being set on the VPN Label or both VPN Label and SP Label I think that only VPN Label would be applied at the Ingress Side and while switching towards Core the SP label would be applied and the same EXP value as the VPN Label would be copied onto the SP Label..

As far as regarding the Cisco document I am not sure in which context it would have been mentioned for Uniform Mode to be the default operation mode of MPLS VPN QoS..May be they meant it from implementation point of view that Uniform Mode is the default choice of implementation but as far as the operational view is concerned MPLS EXP will not be copied down to the IPP at the Egress by default..

Regards

Varma