10 Apr 1995

Diversity

In the nightly business news, the remains of the old Bell system are fighting with cellular phone companies and cable TV to wire up the mythical data highway. To most ordinary users, these battles are no more real than exchanges of phaser fire on Star Trek. A much more limited collection of options is currently available to desktop computer users.

LAN

A Local Area Network carries data at high speeds over short distances. An adapter card plugged into a PC or Mac is connected by phone wire to a "hub" device located in a phone closet or basement of the same building. The hubs are connected by a special grade of shielded copper wire or, increasingly these days, by fiber optic cable.

Two types of LAN architectures are in common use. Ethernet was the earliest and simplest of the LAN systems. It is wide use in universities, government, labs, and engineering. It is supported by all of the vendors and connects to every type of computer. Token Ring LANs were developed by IBM for business applications. The Token Ring adapters are more expensive, but they will automatically detect and recover from most types of failures. The Token Ring has traditionally been considered more reliable and is widely used in corporate offices.

Ethernet is the simplest and least expensive option. An adapter card costs between $60 and $120. The hubs, bridges, and routers are fairly inexpensive. All the freeware and shareware works with Ethernet adapters. Workstations and Macs connect to an Ethernet.Both Token Ring and Ethernet LANs normally connect to the desktop system using two pair of telephone wire. In the original design, the Token Ring depended on a smarter (and much more expensive) adapter card. The hub was designed as a simple device without power or computer chips. Recovery depended on the adapter card detecting a fault and initiating a process to discover the problem and bypass it.

In contrast, Ethernet establishes a connection between the desktop adapter card and a similar circuit in the hub. Data is transferred from the computer to the hub on one pair of phone wires, and is transmitted back on the other. Error recovery, if it exists, is entirely done by the hubs and any other central management tools. Given the technology of the time, Token Ring was more reliable when it came out. However, with the advances in computer chips, Ethernet hubs can now be quite smart. Of course, spending a lot of money on hubs may cancel out the lower cost in the adapter cards.This is not the right forum to discuss the relative merits of the two LAN architectures. In most cases, there will already be wire in the wall and the choice will be decided. If a LAN is to be installed simply for Internet connection, then Ethernet is the least expensive and simplest choice.

Modem

It has been possible to send Internet protocols over phone wires for many years. However, at 2400 bits per second, such a connection was not very attractive. Current modems run at speeds of 14400 or 28800 bits per second before compression, and these speeds are quite adequate for text and ordinary files. Graphics and multimedia will have to wait till the Information Highway makes it to your house.There are two protocols for Internet traffic over a mode. Serial Line IP or SLIP was originally proposed as a temporary ad hoc solution that could be easily implemented and would be replaced when something better came along. It is widely supported in Unix and PC systems and on the devices that connect modems to LANs. Unfortunately, it has taken many years to come up with something better, in part because a new standard had to support not only Internet protocols but also DECNET, Appletalk, Novell IPX, and everything else.Point to Point Protocol PPP is the new and better standard. It is just becoming widely available in all the systems, products, and devices that previously supported only SLIP. Microsoft has put its full support behind PPP for its remote LAN access strategy.When both protocols are available, PPP is preferred. As a newer standard, it addresses some of the setup and management functions that SLIP ignored.

ISDN

Some local phone companies offer a digital service called ISDN. One of the existing pairs of wires at your home or office can be converted to an ISDN "Basic Rate Interface" connection. Two separate logical phone lines (call the "B channels") are carried over the one pair of wires. Each B channel supports 64K bits per second of data transfer. Together they support a data transfer rate of 16K bytes per second before compression.In the US, each customer must purchase the ISDN equipment before the line can be installed. Costs range from $500 up depending on requirements and the discounts that can be negotiated.

There are three ways to connect a PC to an ISDN line.

Looks Like a Modem
An external device properly called a "Terminal Adapter" or just "TA" can be connected to the Serial Port on your PC. In the simplest case, the TA appears to be an ordinary modem. Existing PC software uses standard "AT" commands to dial the phone and to connect to a remote communications controller. An example of this is the 3Com Impact box.
Looks Like a LAN
An external device can be connected to a LAN Adapter card in the PC. This external device acts as a bridge, connecting the remote PC to an Ethernet LAN at some central location. An example of this is the Combinet 160.
Special Drivers
An internal adapter card can be installed in the PC that connects directly to the ISDN line. Unlike the previous two alternatives, this will require Driver software for any operating system that runs on the PC. For example, the IBM Waverunner adapter card has drivers for Windows 3.x. Microsoft supports specific ISDN cards for Windows NT. Microsoft and IBM are both moving toward communications architectures that support the ISDN cards directly. Although the Driver will communicate with the Adapter Card using special programming, the Driver itself will often present an interface to the Internet software that makes it look like a Modem or a LAN Adapter.

Other Network Servers: Novell, NT, ...

Novell has dominated the market for PC file and print servers. Netware represents 80% of the population of installed servers. There are armies of consultants trained on the installation and support of Netware.

However, Novell has been slow to adapt to the new operating systems. The quality of their code and support has been so bad, that Microsoft decided rather late in the schedule to replace all Novell software with their own programming in NT and Chicago. IBM still depends on Novell to deliver a client component for OS/2, but the installation is such a mess that there are two whole "Redbook" manuals to explain how it is done. The full release of OS/2 3.0 is supposed to correct the packaging. The most common explanation for the three to six month delay between the first availability of Warp and the availability of the LAN version is the difficulty getting the Novell piece to install properly.Novell insists on using its own network driver software. This is understandable because the Novell programs are generally held to be more efficient than other packages. The most general Novell software is called "ODI". ODI works in DOS, is a bad idea in OS/2, and was so terrible in NT that one industry newspaper referred to it as the "first known NT virus."Other vendors have come around to the alternate NDIS standard. Although NDIS has traditionally been slightly less efficient than ODI, stability and flexibility count for much in the days of upgradable CPU chips.An ODI software package might be installed on a machine with Plain Old DOS and some version of Windows 3.1 or Windows for Workgroups. If so, Internet connectivity can be achieved by adding a module that converts Packet Driver calls into ODI.However, as a system moves to support more than one network protocol, it is very useful to start from a stronger base. Any upgrade, to OS/2 3.0, to Windows NT 3.5 Workstation, or to Windows 95 (Chicago) will include an integrated Novell Client and instructions for its installation along with support for the Internet and for other NT or IBM OS/2 servers.

Versions of Windows

All new machines come with Windows 3.1 installed. Plain Old Windows has no network support installed. Since it represents a clean slate, any single standard network software package can be added. However, any network software goes in to the area of memory managed by DOS, and may reduce the size of programs that can be run.

Windows for Workgroups (WFWG) has disk file and printer sharing built in. Although WFWG allows the user to load network support into the DOS area, the preferred solution is to wait until Windows starts up and then load the network software into the area of storage above the first megabyte. WFWG 3.1 moves some of the network software into Windows memory, while WFWG 3.11 is able to run the entire network in extended storage (using only 4K out of the DOS area). The "Wolverine" package is available from Microsoft to provide LAN access to the Internet for Windows for Workgroups 3.11, but this package does not provide any dial-up phone support. Any of the shareware or freeware packages designed to add SLIP or PPP to Plain Old Windows will also work in WFWG if the Wolverine package is not installed. Switching between Wolverine for a LAN and a shareware package for SLIP/PPP is simple, but must be done correctly.

Window NT 3.5 has the network server, client, and Internet support built into the system. The system supports Ethernet, Token Ring, modem, or ISDN connection. A single phone connection can provide simultaneous support for Internet, Novell, and NETBEUI communication. Microsoft does not provide client application programs, but a full set of popular tools is available as freeware and shareware in the major network file servers.

Windows 95 (Chicago) is currently undergoing a widespread test. When it becomes available (currently the expected date is August, 1995) it will provide nearly the same range of connectivity that NT 3.5 provides today.

IBM's OS/2 Warp provides the most sophisticated Internet support. An inexpensive "personal" version of Warp has been available for six months providing dial-in access to network services. A more extensive "industrial" version of Warp is currently being tested and should be available shortly. That OS/2 Warp LAN Client will include all the functions of the prevous Warp product, an new Version 3.0 of the TCP/IP for OS/2 base product, a Peer version of the IBM LAN Server 4.0 networking support, and an integrated version of the Novell Client. IBM's main advantage is a large body of client and server programs that effectively use the multitasking features of the operating system. OS/2 client programs can transfer several files simultaneously in the background. The news reader fetches the headers of postings on other topics as the user reviews articles posted on earlier subjects.

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Copyright 1995 PC Lube and Tune -- Windows on the World -- H. Gilbert