In a number of environments, a component external to a network is
called upon to perform computations based on the network topology and
current state of the connections within the network, including
traffic engineering information. This is information typically
distributed by IGP routing protocols within the network
This document describes a mechanism by which links state and traffic
engineering information can be collected from networks and shared
with external components using the BGP routing protocol. This is
achieved using a new BGP Network Layer Reachability Information
(NLRI) encoding format. The mechanism is applicable to physical and
virtual links. The mechanism described is subject to policy control.
Applications of this technique include Application Layer Traffic
Optimization (ALTO) servers, and Path Computation Elements (PCEs).