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IBM and AT&T Join Xerox in the Proliferation of Local Networks.

Local network options continue to proliferate, but communications managers can at last compare the offerings of the industry leaders. During the summer, IBM finally confirmed that its LAN would employ the token-ring technology it has been unofficially endorsing at standards meetings and other technical gatherings. However, the computer giant surprised industry observers by delaying the network's introduction for two to three years. AT&T quickly responded with a local network capable of supporting its new Model 6300 personal computer, as well as the IBM PC family and compatible micros.

Meanwhile, Xerox continues to register impressive gains with Ethernet. Well over 200 companies are now making ethernet products, and Xerox claims to have installed more than 1,000 Ethernet networks in offices around the world. It has also expanded Ethernet communications capabilities, adding the IBM PC family to the more than 20 Xerox office products now operating on the network. The new features allow Ethernet users to access IBM computers using SNA as well as Digital Equipment computers. Also provided is a remote batch computer service on the network for document interchange among computer systems from various vendors.

Rejecting the baseband design supported by Xerox and IBM other computer vendors have come out in favor of broadband systems, which support multimode communications and permit wider geographical coverage. At the same time, the work of the computer and office systems vendors is being supplemented by an active group of component suppliers, such as 3Com and Interlan, and firms that provide general-purpose local-area networks, such as Ungermann-Bass and Sytek.

Component suppliers for the most part target the Ethernet network and the machines of Digital Equipment. Typically, they supply transceivers and controller boards that slot into the associated computer equipment to link it with Ethernet. In contrast, the local-area network suppliers use processor-based interface units that are an order of magnitude more expensive than component vendors' products, but also provide much more functionality. The proliferation of local network options is also being aggravated by the popularity of microcomputers. There is a great deal of effort going into the development of local networks to link microcomputers, workstations and peripherals for resource sharing. Thus far, however, there is little standardization among these efforts. Xerox Builds on Ethernet Success

Xerox turned to 3Com for the hardware to connect the IBM PC directly to Ethernet. Protocol software, which allows an IBM PC user to edit a document on the PC and then access Ethernet network services for electronic printing, filing, mail and mainframe access, was developed jointly by 3Com and Xerox. For the IBM PC and other systems on the network, Xerox internetwork protocols make it possible to access machines not just on one local Ethernet network, but on Ethernet networks in the same building across the country or around the world.

Network users also have access to Digital Equipment computers. Data can be exchanged between an IBM PC or a Xerox Star workstation and a Digital computer to take advantage of the larger machine's faster data processing. Xerox providers software that allows the workstation to emulate a Digital VT-100 terminal. The Star workstation can also be made to emulate IBM 3278 display terminals, providing compatibility with SNA protocols.

Xerox's remote batch service supports IBM 2770/2780/3780 communications protocols as well as flexible document format conversion. Information created on IBM mainframe computers can be sent to Xerox network systems for integration and enhancement; alternatively information created on Xerox systems can be sent to mainframes for processing or archiving.

Last April, Xerox announced the availability of its Interpress Printing Architecture, a set of protocols and formats the enable office machines from different manufacturers to work together for the first time to produce and distribute complex, high-quality business documents on electronic printers. In addition to the Printing protocol, the architecture includes clearinghouse and authentication protocols that play a fundamental role helping users build large, distributed networks that are both reliable and secure. Component Suppliers Target DEC

In its role as joint developer of Ethernet, Digital Equipment is also helping to mesh the local network with its DECnet architecture and its line of professional computers. As part of its upgraded network architecture, DECnet phase IV, Digital offers a number of products to connect the VAX-11 superminis and Unibus-based PDP-11 minis to Ethernet. These products include a communications controller and supporting software, a transceiver and associated cable, and a line of Ethernet calbes. In terms of the OSI reference model, Ethernet provides the physical link and data link protocol, representing the two lowest layers of the model.

Component supplier Interlan of Westford, Massachusetts also links Ethernet with Digital's network architecture through a software package called Etherway. The software was developed by Technology Concepts of Sudbury, Massachusetts, whose two principals, President Stuart Wecker and Vice President Michael Begun, previously worked at Digital as network architects for DECnet. When used with the appropriate Interlan controller, Etherway creates a fully connected DECnet network among the nodes directly attached to the Ethernet. Communications among these nodes is simplified since messages have to transverse only the Ethernet link, in contrast to the routing via intermediate nodes that takes place in conventional networks.

Technology Concepts has supplemented Etherway with two similar gateways for ring and broadband networks, called Ringway and Broadway, respectively. Ringway is marketed by Proteon of Natick, Massachusetts and Broadway by Ungermann-Bass of Santa Clara, California. Using all three gateways, a user could build a network that combines ring, broadband and Ethernet technology, along with point-to-point links, into one DECnet system. Known collectively as Pathway, the three products provide the full range of DECnet functions, including file access, file transfer, remote terminal access and task-to-task communications.

"Because the pathway products make LAN channels appear as standard DECnet links, all DECnet application functions execute transparently over the LAN network," explains Wecker. "Users can select from a variety of LAN networks not supported by Digital. This selectivity saves the user money on hardware costs, creates a degree of network efficiency and improves network reliability."

In August, Interlan announced significant additions to its Net/Plus Ethernet product family, including direct Ethernet connection and network protocol software for the IBM PC and protocol software for Data General MV processors. The Ethernet Direct-Connect package includes a plug-in Ethernet controller, MS/DOS networking software based on the Xerox Internet Transport Protocol (ITP), and a rich set of network diagnostic functions. It provides high-speed communications between IBM PC's and VAX, PDP-11, LSI-11, Unix and Data General systems. Interlan Supports MV series

Interlan also provides Xerox ITP network protocol support for Data General's MV series of computer systems. In addition, the firm has introduced a family of intelligent network processor boards that improve system performance and simplify Ethernet integration in a variety of popular host environments. Available for Unibus, Q bus and Multibus-based systems, the network processors support all the communications protocol layers of the OSI model. Interlan claims that by off-loading protocol-processing activity from the host, the network processor board provides higher throughout and greater CPU availability than link-level controllers. The firm also supports the Transmission Control Protocol/Internet Protocol adopted by the Department of Defense for military communications systems.

Digital Equipment systems are also targeted by 3Com of Mountain View, California. Among its products are transceivers and Ethernet controllers that plug into Digital processors ranging from the low-end LSI-11 micro to the VAX-11 supermini. The firm also offers Ethernet hardware and software for Multibus-compatible micros and IBM computers.

Bridge Communications of Cupertino, California offers a family of programmable communications processors that link Ethernet to non-networked devices and to other local and remote networks. Other firms, such as InteCom and Ztel, provide a bridge between local networks and digital PBXs. InteCom's LANmark adds a 512-Mb/s full-duplex local-area network capability to the Allen, Texas firm's digital PBX, the IBX.

Ztel of Wilmington, Massachusetts used this yearhs ICA show to demonstrate the local-area network capabilities of its Private Network Exchange (PNX). The PNX integrates the LAN with a sophisticated PBX to handle voice and data communications. The LAN employs a 4-Mb/s ring to transport packetized data between devices attached to the ring via RS-232-C connections. Commenting on the demonstration, President Peter Anderson said that the LAN was "the first to conform to what we anticipate will be the IEEE 802.5 draft standard for token-ring LANs".

Unergmann-Bass offers its Net/one system in a 10-Mb/s Ethernet-compatible baseband configuration, as well as a broadband version operating at 5 Mb/s on any of five commonly used CATV channel pairs. Both versions are fully interconnectazble. To provide end-to-end communications, Net/One employs intelligent network interface units (NIUs), which permit communications between a wide range of devices attached to the network.

Last year, Ungermann-Bass became the first to offer an intelligent Ethernet-compatible, board-level NIU for IBM PCs. This year it introduced the industry try's first commercially available fiber-optic Ethernet-compatible LAN. Known as the Fiber Optic Net/One, the system is fully interconnectable with the firm's Net/One baseband and broadband systems.

In other moves to support IBM devices, Ungermann-Bass has developed a version of Net/One to operate on the IBM cabling system. It has also introduced a low-cost network interface controller for connecting IBM PC and selected compatible micros to Net/One. In addition, the firm has signed an agreement with IBM to remarket the IBM PC and PC XT as a "value-added dealer." Under the agreement, Ungermann-Bass will add proprietary network management software and an intelligent interface to the IBM PC, remarkeeting the resulting product as a component of its Net/One system. Ungermann-Bass has also signed a letter of intent to form an independent joint venture company with General Electric to develop, manufacture and market LAN systems for industrial applications.

Last July, the firm introduced an X.25 gateway for Net/One capable of supporting up to 32 virtual circuits and a link speed of up to 65 kb/s. The gateway is certified for use with the Telenet public data network and the AT&T Accunet packet service. In addition, certification procedures are being conducted with Tymnet, and with Datapac in Canada, Transpac in France, Telepac in Switzerland, Datex-P in Germany and PSS in the United Kingdom. More recently, the firm introduced a two-port NIU that reduces the cost of connecting remote stations to Net/One by 50 percent. The NIU-130 allows two RS-232 devices to connect to the LAN, and is priced at $1,400.

Codex also supplies a general-purpose LAN available in baseband and broadband versions. Part of the Mansfield, Massachusetts firm's 4000 Series of Internetworking and Network Management products, the LAN is compatible with Ungermann-Bass' Net/One. Codex is one of the few vendors to offer its LAN on a lease basis. The firm also supports its LAN with a variety of service econom-passing design, installation, certification, application engineering and maintenance.

Applitek of Wakefield, Massachusetts offers a universal local-area network that can provide both guaranteed and contention network access simultaneously on the same channel. Called UniLan, the network operates at 10 Mb/s and uses a unique access method called UniLink. When traffic on the network is light and the active devices are primarily asynchronous, non-intelligent terminals sending short, bursty messages, the network access is similar to Ethernet's. When synchronous devices or computers with regular, frequent traffic are added to the network, network operation dynamically adapts to provide token-passing-type guaranteed access, with bounded transmission delays to those devices. If traffic load increases collisions, then all devices on the network get guaranteed access.

Another aspect of UniLan's universality is its independence from the transmission medium. With the appropriate media access device, UniLan's network interface units can connect user devices to any of the commonly used networking cables, including optical fiber, broadband or baseband coaxial cable. Similarly, the physical organization of cable, user devices and network interface units can be a bus or tree arrangement, whichever is most suitable for the environment. AT&T Uses Fiber Optics in LAN

In announcing its local network in early summer, AT&T gained a two to three-year lead on IBM. The network, called the AT&T Information Systems Network, combines fiber optics and standard twisted-pair copper wire to create a high-speed link between AT&T's new Model 6300 personal computer and mainframes, workstations, terminals, printers and other peripherals.

Built around a centralized packet controller and dual short busses, the local network support speeds to 8.64 Mb/s. One option provides for up to 40 At&T, IBM or other compatible PCs to be linked to a single data concentrator that in turn is connected to the packet controller via fiber-optic cable. Another option allows for twisted-pair wire connections to the System 85 PBX for data transmission at rates to 19.2 kb/s. A third option, the At&T Premises Lightwave System, replaces coaxial cables traditionally used to link IBM 3270 cluster controllers, IBM terminals and printers with fiber-optic cables for communications via the ISN local network.

At the product introduction, AT&T Information Systems officials reported that six beta-test ISN local networks that six beta-test ISN local networks have already been installed for unnamed customers. General availability of the in-house-manufactured local network is scheduled for January. For configurations of more than 1600 devices, the price reportedly works out at between $400 and $500 per drop without new wiring.

Meanwhile AT&T Technologies has introduced software packages to support its 3B minicomputer family over Ethernet and Hyperchannel links. The Ethernet interface is designed for Digital Equipment VAX systems running Unix System V, enabling the systems to communicate ith AT&T's 3B line on the recently announced 3B Net. The Hyperchannel interface provides the software connection between At&T 3B20 minicomputers and other minis running Unix System V via Network Systems Corporation's Hyperchannel proprietary high-speed local network. Commenting on the software products, Harry King, deputy chief of product management for the networking products unit of AT&T Technologies' Computer Systems Division explained. "We're providing our computers with the ability to talk among themselves and with those of other vendors via industry-standard local-area networks." IBM Endorses Token-Ring LAN

Last May, IBM revealed that its longawaited local-area network offering is still "two to three years" away. However, it did finally admit that the network would be based on the token-ring architecture it promoted at meetings of the IEEE 802 committee on local-area network standards. IBM also announced a cabling system designed to reduce the cost and complexity of installing or moving computer devices within a building. IBM explained that its token-ring LAN would be composed of the cabling system and "components planned for announcement at a future date."

The IBM cabling system is permanently wired, with connections made to outlet plates in office walls. IBM estimates the cabling can pay for itself in a few years by elininating most of the expense of moving workstations. The single cabling system can be used instead of coaxial, twinaxial, twisted pair and other special cabling. Using a star topology, the system connects each office wall outlet to a distribution panel in a wiring closet. Wiring closets in the same building or different buildings on a campus can then be connected with either twisted-pair or optical-fiber cable.

A panel can accept up to 64 cables from different devices, and any two devices can be connected easily using patch cables at the closets where the cables converge. For example, if an IBM 3270 PC is moved from one office to another, it is simply plugged into the wall outlet in the new office, and the patch cable in the wiring closet in reconnected. IBM says that most of its currently available products, including workstations and small and intermediate computers, can be plugged into the outlets. IBM says that AT&T Information Systems, Mitel, NEC America, Northern Telecom and Rolm have tested their PBXs and telephones with the cabling system, and report that the voice pairs in the cable "support the full extent of their PBX features and transmission speeds."

Rolm of Santa Clara, California was quick to announce plans to bid, install and maintain the IBM cabling system. Rolm said that its standard wiring plan will continue to be three twisted-pair cable. "The IBM cabling system is an optional wiring plan that can be used in place of combined with, the Rolm plan for those customers who request it," a company spokesman explains.

Ungermann-Bass also plans to offer version of its Net/One local-area network that will operate with the IBM cabling system. President Ralph Ungermann believes that IBM's introduction of a cabling system that will become an industry standard will resolve market confusion over the role of LANs and PBXs in the office environment. "By offering low-cost 'data-grade twisted pair' cabling for LANs and separate 'voice-grade twisted-pair' cabling for PBXs, IBM has, in effect, endorsed the concept of local-area networks," Ungermann says. "We view the announcement as a statement by IBM that local-area newtorks and PBXs will exist side by side in the office environment."

IBM's endorsement of the token-ring architecture should also bring an extra measure of stability to LANs. In presenting the case for its LAN choise, IBM says it favors token passing for a number reasons. It is a distributed access system, which allows each terminal to seize that token and pass information. No central controller is required, and the access delay is predictable and controllable. The token-passing approach also permits the use of priorities, and the bit rate and distance can be increased in line with advances in transmission technology without affecting the basic architecture.

As for ring networks, IBM maintains they are easier to install and make operational. Another benefit is the ability to continually monitor and ascertain the health of each segment of the ring. Any fault is immediately detected by a receiver and can be directly tied to a specific ring segment, so that a problem can quickly be isolated and bypassed or solved. The regeneration of the signal at each station also produces greater token drive distance and noise immunity. While bus systems may have a maximum reach of a few kilometers, ring systems may have a few kilometers between each station.

Also, ring networks are well suited optical fiber, which IBM notes can support the higher speeds and longer drive distances it expects will be required before the end of the decade. For example, data rates in the range of 30 Mb/s at distances greater than one kilometer can be readily achieved with fiber optics. Another attraction of fiber optics is the immunity to electromagnetic interference.

For the ring network, IBM will build on the hierarchical wiring structure of its cabling system, with star connections going from wiring concentrators to offices (see diagram on page 51). This structure has the advantage of providing focal points for systems maintenance and problem determination. The wiring concentrators allow users to quickly find and isolate faulty stations. Further, since the wiring is segmented at the concentrators, it is easier to wire a facility ahead of time and make provision for moving workstations. This arrangement also allows intermixing of transmission media. Multiple rings are linked through a bridge, which is a high-speed digital switching mechannism that provides logical routing transparent to the attached nodes. The network can be further expanded by interconnecting multiple bridges. Finally, gateways provide the link with long-haul networks.

For uses unwilling to wait for IBM's LAN, Proteon of Natick, Massachusetts, offers a similar token-ring network called ProNet. According to President Paul Rosenbaum, ProNet is already operating over the IBM cabling system at Carnegie Mellon and a number of other installations. Rosenbaum adds that the firm is also committed to making ProNet compatible with IBM's LAN, when announced, and the IEEE 802.5 standard for token-ring LANs, when finalized.

ProNet operates at 10 Mb/s over a variety of media, including fiber-optic cable and twisted-pair, coaxial and twin-axial cable. Proteon offers host interface controller boards for Q bus and Multibus systems, as well as for the IBM PC. It also supplies boards for leading minicomputers. ProNet supports up to 255 host nodes and 4,000 RS-232 connections. Its terminal interface unit comes in eight and 16-port versions. Datapoint Opens ARCnet

Token passing is also used by Prime Computer for its Primenet local network, which employs a ring topology, and by Datapoint for its Attached Resource Computer (ARC) local network. Up to eight Prime systems can be interconnected on Primenet, which operates at 8 Mb/s and permits a separation between adjacent systems of up to 750 feet.

Datapoint's ARCnet employs baseband transmission over coaxial cable at 2.5 Mb/s. While it operates logically as a bus, any physical topology can be used as long as no loops are formed. Datapoint began distribution of its ARCnet in 1977, and currently boasts an installed base of over 6,000 such networks.

Last June, Datapoint made a major change in its marketing and development philosophy by announcing its intention to open the proprietary ARCnet to industry-standard technology. "While we still believe it is necessary to have certain proprietary products--to provide maximum capability to our users--we also realize the importance of opening our network to technology from other vendors," explains Edward Gistaro, president and chief operating officer. "By incorporating industry-standard operating systems and hardware manufactured by other companies into the ARC network, we allow a greater diversity of users to take advantage of the resource sharing that makes our local network unique."

Gistaro said that the introduction of the company's new professional computer, the Vista-PC, demonstrates the firm's commitment to opening ARCnet, since the Convergent Technologies-built device brings the MS/DOS operating system into the network. Datapoint plans to integrate the IBM PC into ARCnet and to enhance information access between ARCnet and IBM mainframes, Gistaro added. He also said ARCnet would be able to use the new IBM cabling system.

According to Gistaro, 16 computing and networking vendors are using ARCnet technology, including Wang, Zenith and Nestar, and more than 40 other companies are developing interfaces to it. Nestar uses ARCnet to connect IBM and Apple PCs, and Tandy uses an ABCnet network to interconnect its TRS-80 computers.

Datapoint has also extended the distance between ARC network hubs through the use of fiber-optic cable. Reportedly, the link has doubled the maximum distance between hubs in a network to 4,000 feet. Iowa Power and Light Company is the first to implement a fiber-optic ARCnet. Wang Speeds LAN Installation

In contrast to the other computer vendors, Wang Labs employs boardband technology in its WangNet local network. In April, the Lowell, Massachusetts firm introduced a new version of WangNet geared to small and medium-sized organizations. Called WangNet FastLan, the user-installable calbe system implements the full communications capabilities of WangNet on fixed lengths of cable that provide consistent RF signal levels. This eliminates the lengthy decision and certification procedures of WangNet, which uses a different type of cable, shortening the installation time and reducing the cost.

Wang believes FastLan oiffers an economical way for companies to explore networking within a department before making a large-scale commitment to a customer-design network. It also provides a low-cost networking alternative for companies whose computer equipment is concentrated on two or three floors of a building. FastLan can be incorporated into a custom-designed WangNet installation to form a single network capable of linking an entire building or cluster of building, so it could be a starting point for a WangNet or an add-on branch to an existing installation.

The system consists of three modules: FastLan-A, a $995 broadband RF amplifier; FastLan-B, a $350 network branch with two coupler boxes for connection to the amplifier; and FastLan-C, a $120 drop cable with a four-port WangNet multiuser outlet that connects to a coupler box. These three components can be combined in configurations ranging from four to 640 ports and covering a radius up to 300 feet.

As with the custom-designed WangNet, Fastlan uses a dual-cable broadband medium and CATV components for the concurrent exchange of data, text, image and video information. Five communication services are offered: Wang Band, for communications between Wang systems at speeds to 10 Mb/s; Peripheral Attachment Service, for the independent high-speed connection of Wang workstations and peripherals and IBM 3270 devices to their host systems; Interconnect Band, for transmission pathways for industry-standard communications interfaces and protocols; Utility Band for video applications; and Professional Computer Service, for connecting Wang Professional Computers to the network.

With FastLan, an organization can choose from several installation options. For instance, a user can plan the physical layout, order the necessary modules and by following instructions in the assembly guide, install the network. Atlernatively, Wang will provide full design and consulting services, ad with a customized the physical layout, a customer then installs the network or contracts with a third party to have it installed. As a third option, Wang will provide a total turnkey network.

Fastlan is the most recent in a series of enhancements to WangNet announced over the past several months. These include the Technical Control and Management System, a comprehensive network-monitoring system, and the CMUX-3270 cable multiplexer, a low-cost interface for connecting IBM 3270 display stations and terminals to their 3274 controllers via WangNet. In addition, Wang has been active Wang joined with TRW to propose a dual-cable broadband standard to the IEEE committee.

With the CMUX-3270, Wang offers connections for what it claims are the three largest segments of the terminal interconnect marketplace: RS-232-C, Wang workstation and IBm 3270 devices. Priced at $3.375, the cable multiplexer allows users to substitute the single WangNet transmission medium for the point-to-point coaxial cable between control units and attached devices. Wang's Technical Control and Management System is an integrated set of network monitoring, diagnostic testing and information management tools. Operating on a dedicated Wang VS minicomputer, it compiles information about the location, status and performance of every component in the network. During normal, trouble-free operation, it measures traffic levels, constantly evaluates the quality of network service. In the event of a failure, TCMS automatically notifies the network administrator and helps locate and isolate the cause of the problem. In many cases, it also indicates the remedial action required. The TCMS is priced at $7500. Sytek Chosen for IBM PC Network

One of the leaders in broadband technology is Sytek of Mountain View, California, which has an installed base of more than 500 networks, serving more than 65,000 user devices worldwide. Sytek's LocalNet family includes the less-expensive System 20 for low-throughput devices with serial interfaces, both synchronous and asynchronous, and the System 40, which is designed for relatively high-speed (2 Mb/s) devices with parallel interfaces. LocalNet 50 products, such as access control, monitoring, failure isolation and security. These products also handle inter-network linking functions and long-distance gateways. Products from all three families can co-reside on the same cable, along with a board spectrum of other services. LocalNet is totally vendor-independent and is compatible with mid-split, sub-split and dual-cable installations. Nodes can be located anywhere within a range of 50 kilometers.

In LocalNet, a packet communications unit (PCU) is associated with each user device or group of devices. These units implement the upper six layers of the OSI reference model and provide a broad range of user services and functions, such as protocol translation and virtual terminal support. For network control, Sytek offers the microprocessor-based LocalNet 50/100, which automates network administration, access control, secure communications and other network management services. Its LocalNet 50/201 interchannel bride interconnects PCUs on different frequency channels so tha they can communicate as if they were logically on a single channel. In addition, the bridge can be used to interconnect channels on two separate calbe systems to form a single LocalNet network. Sytek claims that its Secure LocalNet is the only local area network system to provide end-to-end encryption of transmissions between stations on the network. The secure network was used at this year's Democratic National Convention to protect a critical credentials verification data base from unwanted tampering or tapping.

Sytek received a major boost in August when IBM announced it had selected the firm to provide a local-area network for peer-to-peer communications among IBM's stable of personal computers. Although terms of the agreement were not released, industry analysts said that IBM will buy at least 5,000 network packages from Sytek this year alone.

The IBM PC Network is an enhanced version of Sytek's LocalNet 20, operating with a data speed of 2 Mb/s and a CSMA/CD access scheme. The PC network consists of a $695 board-level network adapter that fits into an expansion slot on the PC, a $595 network translator unit that provides broadband frequency translation and cabling components, including a $59 expander. Up to 72 PCs can be connected to each translator unit in a customer-installed network over a 1,000-foot radius, and as many as 1,000 PCs can be linked by joining a series of networks is special installations.

IBM says the PC network will be compatible, through gateways, with its token-ring baseband network, as well as the token-bus broadband network it has under development for industrial applications. To support the PC Network, IBM introduced an enhanced version of its PC Disk Operating System, DOS 3.1, and said a software package called PC Network Program would allow PCs to share peripherals. Both will be available in the first quarter of 1985.

IBM said that the PC Network Program would also run on PCs connected to its future token-ring and token-bus network and on 3270 PCs attached to single display controllers. In a statement of direction, IBM said it intends to interconnect the three LANs and provide each with gateways to System/370 host computers and applications.

For its part, Sytek notes that the LocalNet/PC protocols are not limited to a 72-node network. In fact, the firm says it is prepared to design and implement IBM-compatible growth paths that "will accommodate small and large networking needs as well as a mix of workstations, PCs, terminals and hosts." The LocalNet PC protocols reduce the communications burden of the host by moving the first five protocol layers of the OSI reference model out of the host and into the network. The top two remaining layers--the presentation and application functions--are the only elements of the architecture for which the host is responsible.

IBM's PC Network could "legitimize" the concept of networking micros and lead to a flood of faster, cheaper and more-versatile products. Dataquest of San Jose, California estimates that LANs for personal computers will grow at a 47 percent compound annual rate through 1988. In the opinion of Robert Metcalfe, president of 3Com, interconnecting personal computers will be the major application for Ethernet and similar networks in the future. He expects that his firm alone will connect over one million personal computers via Ethernet before the end of the decade.

Corvus Systems of San Jose, California claims to have provided 13,500 LANs for micros, with a total of 105,000 nodes. Called Omninet, the Corvus networks systems on the same link. Omminet supports IBM PC and compatible models, as well as micros from Apple, Digital Equipment, Texas Instruments, Zenith and Sony. In addition, the network accommodates the firm's own Concept personal workstation and all other Corvus products. Further, a number of major computer suppliers, including NCR, Fujitsu and Olivetti, have licensed Omminet for use with their own systems.

Corvus also supplies bridges to other networks and gateways to mainframe computers. Last November it introduced its SNA Gateway, which links an IBM PC-based LAN to a remote IBM mainframe. Unlike other schemes where the networked PCs emulate 3278 terminals, Corvus' SNA geteway allows the PC to retain its ability to perform local processing functions, as well as acting as a terminal access files, electronic mail, host applications and data bases. Nestar Offer an SNA Gateway

Nestar Systems of Palo Alto, California also offers an IBM SNA gateway as part of its PLAN eries of local-area networks. The gateway allows a dedicated IBM PC on the network to emulate a remote IBM 3274 supporting up to 16 user stations per gateway.

Nestar says it will support the IBM PC Network Pgoram when it become available next year. Nestar's baseband token-passing LAN products will also be compatible with the PC Network Program, so that system and applications software written to exploit the IBM offering will be usable, without modification, in the Nestar PLAN series environment. Nestar says that its standard network interface-cards, cables, hubs, file service, print service and communications service be used as alternatives and extensions the IBM PC Network products to create "higher performance, large capacity systems than IBM has addressed with its network."

Nestar had earlier announced compatibility with the IBM cabling system. In July it introduced a line of six and 16-port ARCnet hubs that can be used to connect either the traditional ARCnet RG-62 coaxial cable, the new IBM cabling system cables or a 200-micron standard fiber-optic cable. In addition to serving as wiring concentrators, the hubs provide signal conditioning that permit up to 22,000 feet of coax between any two nodes, with up to 2,000 feet of coax between any two hubs or a hub and a nodes. Fiber-optic cable doubles the limit to 4,000 feet. Hubs also reduce line noise on a network by automatically supporting signals from ports that are not participating in message transmission, and reduce hazards of possible electric shock by using isolation transformers at each port.

Next year, Nester plans to introduce a gateway to broadband media, permitting PLAN series workstations and servers to communicate over long distances via standard CATV technology. The gateway will allow users to construct wide-area networks using baseband technology for local interconnects, and broadband for longer city-wide distribution.
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Author:Edwards, M.
Publication:Communications News
Date:Nov 1, 1984
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