Egress Engineering over BGP Label Unicast in MPLS-based Networks

Egress Peer Engineering (EPE) is a current technology that is commonly being used to steer egress traffic from an Autonomous System (AS) to external peers via a pre-determined set of links. The steering is generally achieved through a controller that uses Border Gateway Protocol Link-State (BGP-LS) and Segment Routing traffic engineering (SRTE) policies to program the forwarding at the ingress router with a chosen set of MPLS labels that help determine the egress links at the Autonomous System Boundary Routers (ASBRs). An alternate solution is to use BGP Labeled-Unicast (BGP-LU) to distribute the Egress Engineering Labels. We highlight two key limitations in the proposed BGP-LU use-case and provide a solution that mitigates these problem. Our proposed solution is compatible with legacy routers that are currently deployed in production.