PW load share issue on ASR9k


There have 2 path between PE. And customer found 1st path have 5G traffics, 2nd path only have 300M traffics. After checked, customer have Eompls business.

And amount of traffics belong to l2VPN. In general, Loadbalancing in an MPLS network on Cisco routers is typically based upon the data that follows the bottom MPLS label. Refer to All traffic from one PW follows the same path, so have this issue.

We can use Flow Aware Transport (FAT) PW feature (from 4.2.1).

This feature runs on the L2VPN PEs, where it is negotiated between the two ends of a point-to-point or VPLS PW. The ingress L2VPN PE detects flows on the AC and the L2VPN configuration and inserts a new MPLS flow label below the PW MPLS label at the bottom of the MPLS label stack. The ingress PE detects flows based upon the source and destination MAC addresses (default) or the source and destination IPv4 addresses (configurable). With the FAT PW feature, the ingress L2VPN PE inserts one bottom MPLS label per src-dst-mac or per src-dst-ip. The MPLS P routers (between the PEs) hash frames over the available paths, then reach the destination PE based on that FAT PW flow label at the bottom of the MPLS stack.

Follow configuration example:

 load-balancing flow src-dst-ip
 pw-class fat-pw
  encapsulation mpls
    flow-label both
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