Method and apparatus for routing packets in networks having connection ...

[54] METHOD AND APPARATUS FOR ROUTING PACKETS IN NETWORKS HAVING CONNECTION-ORIENTED SUBNETWORKS

[75] Inventor: Ross W. Callon, Bedford, Mass.

[73] Assignee: Bay Networks, Inc., Santa Clara, Calif.

[ * ] Notice: The term of this patent shall not extend beyond the expiration date of Pat. No. 5,633,866.

[21] Appl. No.: 683,863
[22] Filed: Jul. 18,1996

Related U.S. Application Data

[63] Continuation of Ser. No. 560,047, Nov. 17, 1995, abandoned.

[51] Int CI.6 H04L 12/46

[52] U.S. CI 370/238; 370/397

[58] Field of Search 370/60, 60.1, 94.1,

370/94.3, 94.2, 54, 58.1, 395, 397, 238, 389, 392, 398, 399; 340/825.03, 827

[56] References Cited

U.S. PATENT DOCUMENTS

5,115,495 5/1992 Tsuchiya et al 395/200

5,128,926 7/1992 Pedmanetal 370/54

5,233,604 8/1993 Ahmadi et al 370/60

5,251,205 10/1993 Callon et al 370/60

5,452,294 9/1995 Natarajan 370/54

5,491,690 2/1996 Alfonsietal 370/60

5,497,368 3/1996 Reijnierse et al 370/54

OTHER PUBLICATIONS

Callon, et al, "Routing in an Internetwork Environment," The Interoperability Report, Aug. 1989, vol. 3, No. 8, pp. 2-7.

Heinanen, "Multiprotocol Encapsulation Over ATM Adaptation Layer 5," Network Working Group Request for Comments: 1483, Jul. 1993, pp. 1-16.

Laubach, "Classical IP and ARP over ATM," Network Working Group Request for Comments: 1577, Jan. 1993, pp. 1-17.

Kate, et al, "NBMA Next Hop Resolution Protocol (NHRP)," Internet Draft (draft-ietf-rolc-nhrp-04.txt), May 1995.

Moy, "OSPF (Open Shortest Path First) Version 2," Network Working Group Request for Comments: 1583, Mar. 1994. Callon, "Integrated PNNI for Multi-Protocol Routing," ATM Forum Technical Commitee, 94-0789, Sep. 26,1994, pp. 1-7.

Dykeman, et al, "PNNI Draft Specification," PNNI SWG,
ATM Forum 94-0471 R12, Oct. 1995.

Primary Examiner—Benedict V. Safourek
Assistant Examiner—Ajit Patel

Attorney, Agent, or Firm—Blakely Sokoloff Taylor &
Zafman, LLP

A system for routing packets in a network environment having a connection-oriented subnetwork, a plurality of routers coupled to said connection-oriented subnetwork, and a plurality of established virtual circuits. Apacket is received by a router for forwarding toward a packet destination. A best existing virtual circuit across said connection-oriented subnetwork is identified from said plurality of established virtual circuits. The best existing virtual circuit is analyzed to determine whether it is both feasible and efficient for forwarding the packet toward the packet destination. If the best existing virtual circuit is both feasible and efficient, then the packet is forwarded using the best existing virtual circuit. If the best existing virtual circuit is either not feasible or inefficient, then a new virtual circuit is established to an optimal next hop router and the packet is forwarded using the new virtual circuit.

16 Claims, 9 Drawing Sheets