MPLS EXP for L3

You can use class of service (CoS) within MPLS networks to prioritize certain types of traffic during periods of congestion by applying packet classifiers and rewrite rules to the MPLS traffic. EXP classifiers map incoming MPLS packets to a forwarding class and a loss priority and assign MPLS packets to output queues based on the forwarding class mapping. EXP rewrite rules change (rewrite) the CoS value of the EXP bits in outgoing packets on the egress queues of the switch so that the new (rewritten) value matches the policies of a targeted peer. Policy matching allows the downstream device in a neighboring network to classify each packet into the appropriate service group.