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

• US 6,512,768 B1
• Filed: 02/26/1999
• Issued: 01/28/2003
• Est. Priority Date: 02/26/1999
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Thomas, Robert H.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Pham, Brenda
• Application Number:
  US09/258,530
• Time in Patent Office: 1,432 Days
• Field of Search: 370/218, 370/285, 370/389, 370/360, 370/392, 370/395.3, 370/384, 370/400, 370/401, 370/235
• US Class Current: 370/389
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/026 Details of "hello" or keep-alive messages
• CPC Class Codes: H04L 45/507 Label distribution

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.

Claims

1. A tag-switching router comprising:

A. one or more interfaces enabled for tag-switching, each interface having an assigned tag space comprised of incoming tags to be appended to input data packets by a tag-switching peer, said tagged input data packets to be forwarded to the interface by the peer,

B. circuitry at each interface for periodically multicasting an output Hello message in a tag distribution protocol (TDP) protocol data unit (PDU), said output Hello message TDP PDU including a router TDP identifier identifying the tag space assigned to the interface by the router,

C. circuitry at each interface for responding to an input Hello message in a TDP PDU multicast by the peer, said input Hello message TDP PDU including a peer TDP identifier identifying a tag space assigned to the interface by the peer, wherein the router records the peer TDP identifier in a record associated with the interface to create a link adjacency,

D. circuitry for transmitting to the peer an output Bind message in a TDP PDU, said output Bind message TDP PDU including the router TDP identifier, said output Bind message containing advertised tag bindings corresponding to the tag space identified by the router TDP identifier, said advertised tag bindings containing the incoming tags,

E. circuitry for receiving an input Bind message in a TDP PDU transmitted by the peer, said input Bind message TDP PDU including the peer TDP identifier, said input Bind message containing learned tag bindings corresponding to the tag space identified by the peer TDP identifier, said learned tag bindings containing the outgoing tags, and

F. circuitry for appending the outgoing tags to received data packets having destination addresses bound to the learned tag bindings and forwarding the tagged received data packets to the peer from an interface assigned the peer TDP identifier.

2. A method for operating a tag-switching router, said router comprising one or more interfaces enabled for tag-switching, said router performing the steps of:

A. assigning to each interface a tag space comprised of incoming tags to be appended to input data packets by a tag-switching peer, said tagged input data packets to be forwarded to the interface by the peer,

B. periodically multicasting from each interface an output Hello message in a tag distribution protocol (TDP) protocol data unit (PDU), said output Hello message TDP PDU including a router TDP identifier identifying the tag space assigned to the interface by the router,

C. responding to an input Hello message in a TDP PDU multicast by the peer, said input Hello message TDP PDU including a peer TDP identifier identifying a tag space assigned to the interface by the peer, wherein the router records the peer TDP identifier in a record associated with the interface to create a link adjacency,

D. transmitting to the peer an output Bind message in a TDP PDU, said output Bind message TDP PDU including the router TDP identifier, said output Bind message containing advertised tag bindings corresponding to the tag space identified by the router TDP identifier, said advertised tag bindings containing the incoming tags,

E. receiving an input Bind message in a TDP PDU transmitted by the peer, said input Bind message TDP PDU including the peer TDP identifier, said input Bind message containing learned tag bindings corresponding to the tag space identified by the peer TDP identifier, said learned tag bindings containing the outgoing tags, and

F. appending the outgoing tags to received data packets having destination addresses bound to the learned tag bindings and forwarding the tagged received data packets to the peer from an interface assigned the peer TDP identifier.

3. A storage medium containing instructions readable by a tag-switching router processor to cause the router to perform the steps of:

A. assigning to each of one or more router tag-switching interfaces a tag space comprised of incoming tags to be appended to input data packets by a tag-switching peer, said tagged input data packets to be forwarded to the interface by the peer,

B. periodically multicasting from each interface an output Hello message in a tag distribution protocol (TDP) protocol data unit (PDU), said output Hello message TDP PDU including a router TDP identifier identifying the tag space assigned to the interface by the router,

C. responding to an input Hello message in a TDP PDU multicast by the peer, said input Hello message TDP PDU including a peer TDP identifier identifying a tag space assigned to the interface by the peer, wherein the router records the peer TDP identifier in a record associated with the interface to create a link adjacency,

D. transmitting to the peer an output Bind message in a TDP PDU, said out-put Bind message TDP PDU including the router TDP identifier, said output Bind message containing advertised tag bindings corresponding to the tag space identified by the router TDP identifier, said advertised tag bindings containing the incoming tags,

E. receiving an input Bind message in a TDP PDU transmitted by the peer, said input Bind message TDP PDU including the peer TDP identifier, said input Bind message containing learned tag bindings corresponding to the tag space identified by the peer TDP identifier, said learned tag bindings containing the outgoing tags, and

F. appending the outgoing tags to received data packets having destination addresses bound to the learned tag bindings and forwarding the tagged received data packets to the peer from an interface assigned the peer TDP identifier.