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what is MPLS?

rate-limit input rate-limit access-group 101 20000000 24000 32000 conform-action

set-mpls-exp-transmit 5 exceed-action set-mpls-exp-transmit 0

access-list 101 permit tcp any any eq www

i was reading about CAR and jsut started to implement it. and this example was a bit over my head. what does MPLS have to do with this and exactly what is mpls? thank you for you explaination!


Re: what is MPLS?

The rate limit command looks like is applied on an interface running MPLS. MPLS uses tags to tag a packet, so that MPLS enabled routers can switch the packets by looking up the labels, which is much faster (takes place at layer 2) rather than doing a route table lookup, and route the packet. More on MPLS can be read from CCO. MPLS has a quality of service field in the header, similar to TOS (precedence) bits in the IP header. In an MPLS enabled network, the IP ToS bits can be mapped to the EXP (experimental) field in the MPLS header. Both of these are equivalent.

The rate limit command is configured to set the mpls EXP value to 5 for all those packets, which conform to the specfied rate, and for those which exceed the limit, the EXP value is set to 0 ( no priority).

Hope that helps!

New Member

Re: what is MPLS?

that helps alot. thanks for you explain. this defenatly warrents more looking into.

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