Multiple protocol routing

• US 5,430,727 A
• Filed: 05/19/1994
• Issued: 07/04/1995
• Est. Priority Date: 09/04/1990
• Status: Expired due to Term

• Current Assignee: Enterasys Networks Incorporated (Extreme Networks, Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Callon, Ross W.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Jung, Min
• Application Number:
  US08/245,856
• Time in Patent Office: 411 Days
• Field of Search: 370/85.13, 370/85.14, 370/54, 370/94.1
• US Class Current: 370/401
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/03 by updating link state protocols
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/52 Multiprotocol routers
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method for connecting a network so that TCP/IP and OSI 8473 packets may be routed in the same domain. The independence of the addresses is maintained: one device in the network may be assigned only a TCP/IP address, and another device may be assigned only a ISO 8473 address. Furthermore, all of the routers share link state information by using a common link state packet format (such as the ISO 10589 format); thus routes through the network may be computed without regard for the protocols supported by the routers along the route. Where necessary, packets are encapsulated and forwarded through routers which are not capable in the protocol of the packet. In some disclosed embodiments, all of the routers in a given area support a given protocol (or, in fact, have identical capabilities, in which case encapsulation is not required). In these embodiments, the encapsulation is performed by suitable modifications to each router'"'"'s packet forwarding procedures. In other disclosed embodiments, these topological restrictions are removed, and the network is expanded to support additional protocols. In these embodiments, the Dijkstra algorithm is also modified to generate information on how to encapsulate and forward packets through the network.

Claims

1. A method of enabling user data packets to be forwarded from one local area network to another by a device which is capable of acting as a router to recognize and forward to and from end systems user data packets which conform to a first protocol suite and is capable of acting as a bridge to recognize and forward between networks user data packets which conform to at least a second protocol suite, said method comprising

for a user data packet which conforms to said first protocol suite and is addressed to a single address which is not an address of the device, causing the device to act as a bridge rather than as a router.

2. The method of claim 1 wherein said first protocol suite comprises a TCP/IP protocol suite.

3. The method of claim 2 further comprises causing said device to act as an IP router when forwarding IP packets.

4. The method of claim 1 wherein said second protocol suite comprises an OSI protocol suite.

5. A device which is capable of acting as a router to forward to and from end systems user data packets and is capable of acting as a bridge to forward between networks user data packets, said device comprising

router circuitry causing said device to act as a router recognizing and forwarding user data packets conforming to a first protocol suite,

bridge circuitry causing said device to act as a bridge recognizing and forwarding user data packets conforming to at least a second protocol suite,

control circuitry causing said device to act as a bridge rather than as a router for a user data packet which conforms to said first protocol suite and is addressed to a single address which is not an address of the device.

6. The device of claim 5 wherein said first protocol suite comprises a TCP/IP protocol suite.

7. The device of claim 6 wherein said router circuitry causes said device to act as an IP router when forwarding IP packets.

8. The device of claim 5 wherein said second protocol suite comprises an OSI protocol suite.