BGP link state distribution

Junos OS introduces a new mechanism to distribute topology information across multiple areas and autonomous systems (ASs) by extending the BGP protocol to carry link state information. Earlier, this information was acquired using an IGP, which has scaling limitations when it comes to distributing large a database. Using BGP provides a policy-controlled and scalable means of distributing the multi-area and multi-AS topology information. This information is used for computing paths for MPLS LSPs spanning multiple domains, such as inter-area TE LSP, and enables external path computing entities, such as ALTO and PCE, to acquire network topology.