Method for synchronizing network address translator (NAT) tables using the open shortest path first opaque link state advertisement option protocol

• US 6,418,476 B1
• Filed: 06/29/1998
• Issued: 07/09/2002
• Est. Priority Date: 06/29/1998
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Luciani, James V.
• Primary Examiner(s): Geckil, Mehmet B.
• Application Number:
  US09/107,097
• Time in Patent Office: 1,471 Days
• Field of Search: 709/238, 709/239, 709/240, 709/241, 709/242, 709/244, 709/245, 370/409, 370/401, 370/351, 370/389
• US Class Current: 709/238
• 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 45/03 by updating link state protocols
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/2532 Clique of NAT servers

Abstract

A method for distributing Network Address Translator (NAT) translation table information among border routers associated with a routing domain using the Open Shortest Path First (OSPF) Opaque Link State Advertisement (LSA) option protocol. The NAT translation table information is included in an application specific field following the LSA header. LS type 9 LSA packets are used to limit the flooding scope to the local network segments attached to the border router. Network address information, i.e., local network address and corresponding global network address, are transmitted in the application specific field of the Opaque LSA packet. The Opaque LSA packets are exchanged between a group of interconnected Opaque LSA capable border routers so that the border routers can maintain identical NAT translation tables as necessary to forward data packets according to the NAT forwarding paradigm.

Claims

1. A method for a border router associated with a routing domain to distribute network address translator (NAT) translation table information to interconnected border routers in the routing domain, comprising the steps of:

a) inserting the NAT translation table information into an Open Shortest Path First (OSPF) Opaque Link State Advertisement (LSA) packet; and

b) distributing the OSPF Opaque LSA packet to the interconnected border routers.

2. The method of claim 1, wherein inserting the NAT translation table information into an OSPF Opaque LSA packet comprises inserting the NAT translation table information into an application specific field of the OSPF Opaque LSA packet.

3. The method of claim 2, wherein inserting NAT translation table information into an application specific field of the OSPF Opaque LSA packet, comprises:

a) inserting a local network address into a first field of the application specific field; and

b) inserting a corresponding globally unique IP address into a second field of the application specific field.

4. The method of claim 1, wherein distributing the OSPF Opaque LSA packet to the interconnected border routers, comprises:

a) setting the flooding scope for the OSPF Opaque LSA packet to local network segments; and

b) advertising the OSPF Opaque LSA packet to the interconnected border routers within the flooding scope.

5. A method for distributing network address translation information from a first network device to a second network device, comprising:

at the first network device, providing a data unit that includes both network address translation information and at least some network topology information, the data unit is an Open Shortest Path First (OSPF) Opaque Link State Advertisement (LSA) packet;

transmitting the data unit from the first network device to the second network device; and

at the second network device, employing the network address translation information from the data unit to update any existing network address translation information.

6. The method of claim 5, wherein the transmitting of the data unit step further includes the steps of:

setting a flooding scope for the OSPF Opaque LSA packet to local network segments; and

advertising the OSPF Opaque LSA packet to interconnected border network devices within the flooding scope.

7. A data structure embodied in software stored on the machine-readable medium for distributing network address translation information from a first network device to a second network device in a computer network, comprising:

at least one field containing link state information that indicates reachability of at least one device in the computer network; and

at least one application specific field that contains Network Address Translator (NAT) translation table information.

8. The data structure embodied in software stored on the machine-readable medium of claim 7, wherein said network address translation information includes at least one local network address and at least one corresponding globally unique network address.

9. The data structure embodied in software stored on the machine-readable medium of claim 7, wherein the globally unique network address is an Internet Protocol (IP) address.

10. The data structure embodied in software stored on the machine-readable medium of claim 7, wherein the local network address is an Internet Protocol (IP) address.

11. A network device for distributing network address translation information to at least one other network device, comprising:

a plurality of ports;

interconnection circuitry that facilitates transmission of data units between the plurality of ports within the network device, the data unit includes an Open Shortest Path First (OSPF) Link State Advertisement (LSA) packet;

circuitry that provides a data unit that includes both network address translation information and at least some network topology information; and

circuitry that prompts transmission of the data unit to the at least one other network device via at least one of the ports.

12. The network device of claim 11, including circuitry that places a local Internet Protocol (IP) address into a first field of the packet and a corresponding globally unique IP address into a second field of the packet.

13. The network device of claim 12, wherein the network device includes a network border router.

14. The network device of claim 13, wherein the network device includes a network switch.

15. A method for distributing network address translation information from a first network device to a second network device, comprising:

at the first network device, providing a data unit that includes both network address translation information and at least some network topology information, the providing of the data unit includes inserting Network Address Translator (NAT) translation table information into an application specific field of an Open Shortest Path First (OSPF) Opaque Link State Advertisement (LSA) packet;

transmitting the packet from the first network device to the second network device; and

at the second network device, employing the network address translation information from the packet to update any existing network address translation information.

16. The method of claim 15, wherein the providing of the packet includes:

inserting a local network address into a first portion of an application specific field of the data unit; and

inserting a corresponding globally unique Internet Protocol (IP) address into a second portion of the application specific field.