ISDN interfacing of local area networks

Details ISDN interfacing of local area networks ISDN interfacing of local area networks

1993-12-14

1995-08-15

Kizou, Hassan

Multiplex communications

Wide area network

Packet switching

370 941, 3701101, 370118, H04J 326, H04L 1266

Patent

active

054426308

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The invention is directed generally to Integrated Services Digital Networks (ISDN), and more particularly to interfacing local area networks to an ISDN line.


BACKGROUND ART

Utilization of personal computers in business and scientific applications has proliferated considerably over the past decade. There is increasing use of small, single-function systems, such as word processors and small business computers. To share and exchange data between system, and to share resources, systems have been constructed as a centralized network having a single centralized controller operating multiple terminals in a time shared manner. This has evolved into a so-called distributed network which divided tasks among computing facilities, each termed a "node"; the intelligence residing at each node is termed a "host".
Distributed networks can be organized in a number of ways, either globally covering great distances or they can be local area networks (LAN) covering relatively short distances. A LAN ordinarily will consist of computers distributed within an office, a building or a campus. More information on local area networks is available in numerous texts, such as Keiser, Local Area Networks, second edition, McGraw Hill, Inc., 1989.
Three basic methods to connect local area networks to other networks are bridgers, routers and gateways. Bridges are data-link layer devices that connect similar networks together, e.g., Ethernet to Ethernet. Routers operate at Layer 3 of the OSI model, performing alternate routing by maintaining a routing table in each host. Gateways operate at the higher OSI Layers, carrying out protocol conversion and other connectivity functions. The term "gateway" will be used hereinafter as a term generic to bridgers, routers and gateways.
Personal computers or local area networks are interconnected by a transmission medium, such as coaxial cable, twisted wire pairs and optical fibers, depending principally on the rate of data transfer required. The present invention utilizes Integrated Services Digital Network (ISDN) to enable local area networks to be interconnected with each other to form a wider area network or to enable a local area network to be accessed by a remote personal computer and operated as if the computer were resident on the network.
ISDN is a relatively newly developed and emerging field of telecommunications which integrates computer and communications technologies to provide, worldwide, a common, all-digital network. This is based, in part, on standardizing the structure of digital protocols developed by the International Telegraph and Telephone Consultative Committee (CCITT). Despite the implementation of multiple networks within national boundaries, from a user's point of view there is a single, uniformly accessible, worldwide network capable of handling a broad range of telephone, data and other conventional and enhanced services.
A complete description of the architecture of ISDN is beyond the scope of this specification. For details, and for an extensive bibliography of references on ISDN, see Stallings, ISDN, An Introduction, MacMillan Publishing Company, 1989.
ISDN is structured by architecture closely following the OSI Seven Layer Reference Model. Within the framework of ISDN, the network provides services and the user accesses the services through the user-network interface. A "channel" represents a specified portion of the information carrying capacity of an interface. Channels are classified by two types, Basic Rate ISDN (BRI) and Primary Rate ISDN (PRI). BRI delivers two B-channels, each having a capacity of 64Kbps, capable of transmitting voice and data simultaneously. A 16Kbps D-channel transmits call control messages and user packet data. PRI provides twenty three B-channels of 64Kbps capacity each for carrying voice, circuit switched data or packet data. The D-channel is a 64Kbps signaling channel. The B and D channels are logically multiplexed together at Layer 1 of the OSI Reference Model.
FIG. 1 depicts the conventional ISDN interfaces. At the cust

REFERENCES:
patent: 4706081 (1987-11-01), Hart et al.
patent: 4805167 (1989-02-01), Leslie et al.
patent: 4926420 (1990-05-01), Shimizu
patent: 4996685 (1991-02-01), Farese et al.
patent: 5208811 (1993-05-01), Kashio et al.

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