EXP-COS mapping on 3750M

Unanswered Question
Jul 9th, 2008
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Hi,


I am using 3750 as a L2 switch in between MPLS PE and MPLS P router. The ports (on 3750M) connecting to MPLS devices are just L2 ports no IP or no LDP. I want to know if I can configure QOS on L2 ports of 3750. Can I map MPLS EXP to COS on switch?


regards,

Gaurav

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lee.reade Wed, 07/09/2008 - 05:29
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Hi,


You will not be able to do this, as the switches look at the layer 2 or 3 cos markings, whilst the MPLS exp value is at layer 2.5, between the IP and MAC layers.


But if the MPLS exp value has been set from that of the IP precedence/DSCP from the CE packet, aka uniform mode MPLS QOS, then you can just use your cos maps to match the ip dscp/precendence to cos etc.


HTH


LR

chintan-shah Wed, 07/09/2008 - 06:24
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Hi LR,


If same configuration i have for 6500 ( L2 config , no L3 config , no mpls enabled on mpls). Is It possible to look MPLS EXP or I need to have interface mpls enabled (ip mpls).


Regards,

Chintan

lee.reade Wed, 07/09/2008 - 06:38
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Hi,


You would not be able to see the mpls labels as they are not being MPLS switched throughout the 6500, they are being normal layer 2 switched.


You could put a sniffer onto the 6500 and span the traffic and view the labels that way, i suspect.


HTH


LR

chintan-shah Wed, 07/09/2008 - 06:43
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Hi,


Thanks. Does it mean that I need to have interface enable with MPLS ( ip mpls) and configure normal MPLS stuff to enable switch to look MPLS Exp bit and then i can have Qos based on MPLS EXP bit??


Regards,

Chintan

lee.reade Wed, 07/09/2008 - 06:48
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Hi,


Yes that is correct.


Or if its a L3 switch, then you should be able to use the IP dscp markings also.


Cheers,


LR

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