Discovery and tag space identifiers in a tag distribution protocol (tdp)

Abstract

A tag-switching router on a tag-switching network establishing a single tag distribution protocol (TDP) session with a peer for the advertisement of tag bindings shared by two or more interfaces and contemporaneously establishing with the peer one or more additional TDP sessions for the advertisement of tag bindings dedicated for use by specific interfaces. Each router interface has an assigned tag space comprised incoming tags that are appended by the peer to input data packets forwarded by the peer. A new Hello message carried in a TDP protocol data unit (PDU) is introduced for use in a TDP discovery mechanism. The router periodically multicasts a specific Hello message from each tag-switching enabled interface and a router TDP identifier in the TDP PDU header identifies the tag space that the router has assigned to the interface. When the router receives a Hello message from the peer at one of its interfaces, the router records the peer TDP identifier in a record associated with the interface to create a link adjacency. The router and peer establish a conventional TDP session to exchange tag binding sets. The router transmits to the peer a Bind message containing advertised tag bindings which, in turn, contain the incoming tags for the tag space identified by the router TDP identifier in the TDP PDU header. The router receives from the peer a Bind message from the peer containing learned tag bindings which, in turn, contain the outgoing tags for the tag space identified by the peer TDP identifier in the TDP PDU header. The router appends outgoing tags to received data packets having destination addresses bound to the learned tag bindings and forwards the tagged received data packets to the peer from the associated interface.