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New Member

MPLS QoS

Hi,

I have two questions:

1. Can anyone put in plain words the differences between E-LSP and L-LSP and what would be a valid application of each?

2. Is it correct that when poping labels the EXP value is not copied to a revealed label by default (as opposed to push and swap) and you need to use qos-group to make LSR "remember" the EXP value so it can apply it to a new label.

Thanks,

David

6 REPLIES

Re: MPLS QoS

Hi,

I would assume the post

http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Service%20Providers&topic=MPLS&CommCmd=MB%3Fcmd%3Ddisplay_location%26location%3D.1ddae096

should pretty much answer your first question.

For the second question the answer is: yes, this is true. On selected platforms you can use "mpls propagate-cos" to achieve the copying from EXP to DSCP.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: MPLS QoS

Hi Martin,

What would EXP to DSCP copying achieve? Is that applicable to label poping in MPLS core?

David

Re: MPLS QoS

exp to dscp copying is useful in case you have the "uniform mode" of QoS, where any changes in exp bits should be reflected in changes in DSCP.

New Member

Re: MPLS QoS

Martin,

Sorry to hijack the thred.

May I know on selected platform can use "mpls propagate-cos" - is that a command supported in most MPLS IOS or maybe global configuration? Try to dig out the command but couldn't find. :)

cheers.

maher

New Member

Re: MPLS QoS

Hi,

There is much info on that command. It would seem that it simplifies Uniform tunnel mode configuration by allowing to avoid "set ip dscp" policy-map statements on egress PE towards the customer.

With this command EXP value is automatically copied into IPP field of outbound (untagged) packet.

David

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