Hybrid units for a communication network

Patent 5491692 Issued on February 13, 1996. Estimated Expiration Date:

December 23, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

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4972409

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Inventors

Assignee

Digital Equipment International Limited

Application

No. 173719 filed on 12/23/1993

US Classes:

370/402, Bridge between bus systems370/407, Interconnected star couplers370/408Nodes interconnected in hierarchy to form a tree

Examiners

Primary: Olms, Douglas W.
Assistant: Nguyen, Chau

Attorney, Agent or Firm

Johnston; A. Sidney, Dagg; David A.

International Class

H04L 012/46

Foreign Application Priority Data

1991-06-14 GB

Abstract

A communication network consists of end units (EUs) and distribution units (DUs) coupled together by links which may include local area networks (LANs). The units maintain neighbor tables by sending out Hello messages which indicate the unit type and contain the network service access point (NSAP) IDs or addresses of the units. Data messages (packets) mainly originate and end at EUs. An EU maintains only partial routing information about neighbors, while the DUs collectively maintain complete information about all NSAPs. So if an EU wants to send a packet to an EU which is not a neighbour (and sometimes even if it is), it need merely send it to a neighboring DU; that DU, along with the other DUs, must find a route to the destination EU. This invention provides a hybrid unit (HU), which acts as a DU to EUs but as an EU to DUs. The HU provides DU-like message forwarding but only on a local basis within a subnetwork of EUs and HUs.

Other References

European Search Report dated Oct. 19, 1992, Application No. 92305212.0
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IEEE Military Communications Conference, Oct. 1986, Monterey, California, U.S.A., pp. 15.3.1 through 15.3.13. Title: "Reducing Routing Overhead in a Growing DDN". Authors: J. Seeger, et al
IEEE Journal on Selected Areas in Communication, vol. 7, No. 7, Sep. 1989, New York, New York, U.S.A., pp. 1131 through 1142. Title: "Networking of Networks: Interworking According to OSI". Authors: Fred M. Burg, et a