LAN (Local Area Network)

Certainly not new, and now appearing even in homes, New uses are constantly being found for LANs.

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Introduction

LANs (Local Area Networks) were originally put in by small businesses so users could share an expensive laser printer and/or accounting files. Today, the network is the computer, providing a myriad of communications and Internet access tasks. Typical uses are:
  • File sharing: for accounting, customer contact software.
  • Printer sharing: now as much to reduce the clutter of printers everywhere as to share the cost of a single expensive printer.
  • Fax from the Desktop: for efficient use of time and better looking faxes.
  • Internet / Intranet Access: as these technologies take over everything.
  • Project Colaboration: to cut way down on meetings.
  • Calendar: so everyone can work themselves into the overall schedule and know who will be available when.
  • Backup: multiple computers can be backed up over the network, automatically, to a single tape.

So important have LANs become, and so inexpensive, it is becoming rare to find even the smallest garage or spare bedroom operation that doesn't have multiple computers connected with a LAN.

History

Small business networks were pioneered by Novell. They started out with the intention of sharing a costly hard disk, but the falling price of hard disks changed their mind and they went for file sharing. Without the expertise to actually write a network, they bought a license for an old Unix kernel, and started modifying it.

Until this time, networks had been very costly and proprietary to one or another of the big computer companies. Novell, when faced with the choice of who's hardware to support, chose "all of the above". It was a hard choice, but made the company. Novell made small business networking affordable by subsidizing the cost of Ethernet cards (until volume took care of the price). Novell created a very fast proprietary networking protocol, IPX/SPX.

NetWare is a "server based" network. In other words, it requires a dedicated server that can be used for nothing else. This is really the way to go, but in those days that server was very expensive.

Not to be left out in the cold, IBM designed a network protocol called NetBIOS and a primitive network called PCNet. It was no NetWare, for sure, but it was "peer-to-peer" and didn't require that expensive server. IBM, of course, screwed it up other ways and it didn't really catch on. As of March 2000, we still have one client still on PCNet, but they are about to decommission it.

Small business networking really took off when Artisoft adopted IBM's NetBIOS and ran real networking software over it (LANtastic). It was now possible to have a full functional LAN without the expense of that dedicated server. Of course, a lot of LANtastic installations, because they were supposed to be simple, were done poorly by do-it-yourselfers and didn't work well, which kept Artisoft's reputation a little shaky compared to Novell's.

Automation Access put in a lot of Artisoft's LANtastic because it was cheap and required almost no support, while other integrators put in a lot of NetWare because it was expensive and generated a lot of support revenue. What can I say? We're dumb.

Microsoft attempted for a long time to get into the network business, including OEMing 3Com's now extinct 3Net network, which got plowed under big-time when a prominent performance comparison "shoot-out" was won by Novell. Microsoft made no progress until they decided to give away networking free with Windows for Workgroups 3.11. This was based completely on IBM's old PCNet with patches and kluges to make it work with newer hardware and software. WFW was soooo bad businesses paid gladly for other networks so as not to have to use it.

Meanwhile IBM folded PCNet into OS/2, making it compatible with Microsoft Networking, but much more reliable and usable.

A small network company called Web reverse engineered Novell's IPX/SPX transport and issued a network similar to PCNet that could use NetWare network card drivers. Microsoft bought Web outright to get that IPX/SPX clone and liquidated the company in about an hour. Now they were prepared to go after NetWare networks in a big way.

With the release of Windows95, Microsoft improved MS Networking to the point it was usable, but pretty poor compared to the alternatives. Still IBM's NetBIOS with a new layer, NetBEUI (Enhanced User Interface) running on top of it. LANtastic was still a lot better, but going against "free" isn't easy.

When Windows NT was released it was still based on IBM's old PCNet NetBIOS with NetBEUI, and patches on patches on patches and kluge over kluge (read John D. Blair's Samba for a good rundown). Now Microsoft used their tremendous marketing power (and ability to create incompatibilities) to try to kill Novell. Novell, having been practically a monopoly, was as fat and happy as monopolies get, and wasn't at all prepared for the onslaught. Nearly all of Windows NT's gains came at the expense of NetWare.

Today, things are changing. TCP/IP "the interim protocol that stayed for dinner" will push NetBIOS, IPX/SPX and all other network protocols into oblivion. Samba, has come on the scene, allowing cheap reliable Linux servers (and expensive, reliable Unix Servers) to pretend they are NT servers supporting Windows, DOS and OS/2 workstations. Linux/Samba servers are replacing both NetWare and Windows NT in many businesses.

How Does a LAN Work?

A LAN allows certain computers on the network to offer their resources (hard disks, floppy disks, CD-ROMs, Printers, Modems, etc.) for use by other computers on the network as if they were their own. Computers that offer resources are called Servers.

Computers called Workstations can attach the resources (typically hard disks and printers) offered by servers as if they were their own. For instance, at AA Company, computer #1 has a C: hard disk and a D: CD-ROM. Computer #2 has a C: hard disk and a D: CD-ROM, but computer #2 also attaches computer #1's C: drive as it's own F: drive. To the user of computer #2 it looks as if drive F: is in his own computer. He can use files and programs from the F: drive just as he can from his own C: drive. The network software module that performs this slight of hand is called the redirector.

A computer can be both a Server and Workstations at the same time, in which case it is called a Peer. Networks without dedicated servers are called peer-to-peer networks. Networks with one or more dedicated servers are called server based networks even though they may also have peers on them.

Back to our example. The network computers #1 and #2 are on has a server, computer #3. Computers #1 and #2 each have a copy of an accounting program on them, but both read and write accounting data to their G: drive, which is actually C: on computer #3. The tape backup unit is on computer #3 and backs up all the accounting data for all the computers every night by backing up its own C: drive.

When computers #1 and #2 are using the accounting software that software is running in their own memories. The server is not involved at all except to offer its hard disk for data storage. This server is called a file server.

Since this is a Windows accounting package it is big and slow and swaps to disk a lot, so each computer has it installed on its own hard disk to get decent performance. In the days of small fast DOS programs, workstations would also load the program from the server, so it only had to be installed once in one place.

When computers #1 and #2 do sorted reports, every record has to be read from the server and sorted in the memory of the workstation and written back to temporary files on the server. This causes a lot of network traffic on a larger network.

Lets say AA Company grows a lot and now still has computers #1, #2 and server #3 but has added additional workstations #4 through #29 - and lots of users of the accounting software. all that network traffic causes the network to get really bogged down and users start to complain.

What AA Company does now is ditch that Windows accounting package and install a new multiprocesor Compaq server running Windows NT. The new accounting package uses the Oracle database program to store its data at the server. This new package actually runs on the server (which is now called an application server because it has applications programs running on it). The workstations just have a client program that asks for records and has input and viewing screens. If a client asks for a sorted report all the work is done at the server, cutting network traffic way down. This is called a Client Server network.

Meanwhile, across town, BX Company started with its accounting on a Xenix host computer with some "green screen" terminals wired to it (instead of PCs like AA Company used). There was no network at all, just a lot of serial cables connecting dumb terminals and printers to the host computer.

As it grew, BX upgraded to a Unix host computer and added some PCs that were also wired back to the host and ran terminal emulation software so they could act as terminals to use the accounting. Some of the PCs also got their own printers, which also act as slave printers to the Unix box. Still no network.

Finally, BX Company needed to exchange marketing and project files among the PCs, so they installed a peer-to-peer network connecting all the PCs, and included their big honk'n Sun Enterprise Unix box in the network too. The PCs dumped the terminal emulation package and use telnet which allows them to act as terminals over the network - no more serial cables. Later they add a Linux box to the network to act as a file server, as an Intranet Web server and as a firewall for their DSL connection to the Internet.

BX Company now has a hybrid network (and still has some of the old green screen terminals working out in the warehouse).

So which company did networking the right way? Depends on the details. AA Company got prettier accounting and a lot of PC flexibility early on, while BX Company definitely got a lot of bang for their buck, and higher reliability. If BX really needed the PC flexibility and AA really needed high performance and 24/7 reliability, then they both did it wrong.

Which LAN is for You?

There is still a wide selection of networks for a small business to choose from, though many minor players and a couple major players (3Com, Banyan) have cashed in whatever chips they had left.

Novell NetWare

Novell NetWare has only one competitor for fast file and print services, OS/2 Warp Server. NetWare is extremely stable, with next to no downtime.

Designed to support very large enterprises, NetWare requires highly trained administrators (but in a small business it needs almost no administration, so a guy who comes in once in awhile is plenty).

Novell offers an "all in one" small business package, NetWare for Small Business which provides all the server packages and Internet/Intranet support a business with 10 to 50 PCs is likely to need.

NetWare provides excellent support for Internet and Intranet services, and excellent security. It is totally immune to virus infection.

NetWare is a server only, and supports Windows95/98, Windows NT/2000, DOS, Windows 3.1, OS/2 and Linux clients.

Windows NT/2000 Server

Typically Microsoft, NT and Windows 2000 do just about everything - but nothing outstandingly. NT is the slowest and least reliable network server widely used, but makes an acceptable applications server.

Windows NT has proven a most costly network because low performance requires about 3 times as many servers as with NetWare or OS/2, and a large amount of administrative effort to keep it running. We are told Windows 2000 performs better, is much more reliable and less costly to maintain, but we won't really know if that is true for nearly a year. Microsoft is gearing up to "encourage" people off of NT as quickly as possible.

We recommend you evaluate adopting Windows 2000 very carefully, because the full function of Windows 2000 networking requires a total commitment to Microsoft, Windows 2000 and Active Directory (implemented only on Windows 2000). Attempting to mix Windows 2000 with any other operating systems, even Windows NT and/or Windows95/98, will make most of Win2000's advanced features unavailable.

There are severe security ramifications to running the uniform, highly integrated "all Microsoft" environment, especially given Microsoft's inattention to security in general. A viruses infection can bring down your entire network in a matter of minutes.

Certain Microsoft applications (IIS, SQL Server, Exchange) require an NT/2000 server and will run on nothing else. If you feel you need one of these, you have no choice whatever. This is by design.

Windows 2000 fully supports only Windows 2000 clients, but partially supports Windows NT, Windows95/98 and OS/2 clients (OS/2 reluctantly). Windows NT supports Windows95/98, Windows 3.1, Windows NT/2000, DOS and OS/2 clients.

OS/2 Warp Server

As fast as NetWare, as stable as Unix, with a journaling filesystem and many other enterprise amenities, OS/2 Warp Server is the best all around network server, and is compatible with Microsoft Networking too. On top of all that it costs less than Windows NT. Unfortunately IBM has failed to market it aggressively and it has practically faded from public view. Important divisions of IBM prefer the much greater service revenue they can get from Windows NT to a product of their own that simply doesn't need service.

Excellent support for Internet/Intranet and eCommerce applications. The current version (Warp Server 5.0) is being marketed specifically to support eCommerce applications.

OS/2 Warp server supports OS/2, DOS, Windows 3.1, Windows95/98, and Windows NT/2000 clients.

SCO Unix

Highly reliable, excellent security, great flexibility, superior support of Internet/Intranet applications, scalable from "mom and pop" to megacorp. Moderate performance as a file and print server. Unlike the other servers listed here (except Linux) SCO Unix can also act as a host serving Unix applications to terminals and PCs acting as terminals.

Generally you will choose the SCO Unix environment if you are adopting a software package that runs on SCO Unix. Beyond that, this server can provide all the other network services and, by running Samba, present itself to networked PCs as if it were an NT server.

Tarantella, an add-on product, allows SCO Unix to serve practically any applications to any computer anywhere that has a Web browser. You can even serve up Windows NT applications to non-Windows computers as long as they have a Web browser (of course you have to have an NT server somewhere on your network to do this).

It is a good thing for SCO they have a lot of well integrated high-end products, because at the low end their lunch is being eaten by Linux.

Linux

Linux, for all practical purposes, is Unix, so practically anything said of Unix applies also to Linux, except for cost. Linux is very affordable, at $6.00 to $199.00 depending on the distribution and number of commercial applications included in the distribution.

Extremely stable, with good to excellent security (depending on configuration) Linux provides excellent support for Internet/Intranet applications (many Internet Service Providers run on Linux).

By use of Samba, Linux can present itself to a PC network as if it were a Windows NT server. Linux server performance is considerably better than Windows NT/2000 on modestly priced server hardware, not quite as good on very high end hardware (but this is being addressed).

Linux cannot run Microsoft server based applications that are designed to lock you into Windows NT/2000 (IIS, Exchange, SQL Server), but better equivalents of these are easily available (Apache, HP Open Mail, (Oracle, Informix, DB2)). As a Web server Linux can now serve applications written using Microsoft's ASP (Active Server Pages).

By clustering, Linux can provide super computer level performance at a small fraction of the cost (the U.S. Postal Service uses 900 Linux clusters to sort the mail).

Like other versions of Unix, Linux can support terminals, PCs acting as terminals, and any number of modems and printers.

OS/2 Peer-to-Peer

If you chose OS/2 as your desktop operating system, you get the best peer-to-peer network right along with it. If you don't chose OS/2 as your desktop operating system, you can't have it. Simple as that. This is the same NetBEUI/NetBIOS network as Microsoft uses, except done right (and Windows95/98/NT computers can be included in an OS/2 network).

High levels of security can be implemented using third party security packages. Performance is excellent and it never has the Master Browser problems so common with Windows networking.

Excellent support for Intranet/Internet applications and all forms of communications.

OS/2 peer-to-peer supports OS/2, DOS (partial), Windows 3.1, Windows95/98 and Windows NT/2000 workstations.

Artisoft LANtastic

Once the premier peer-to-peer network for small business, LANtastic was targeted by Microsoft for destruction, a destruction that is almost complete today. While higher in performance than Windows Networking, LANtastic is forced to use Windows95/98 network services, so there is a limit on how good it can be.

LANtastic is still a good choice if you need some security and tighter administration control than is available with Windows95/98 networking (none).

LANtastic is still much used in POS (Point of Sale) systems, most of which are still DOS based for simplicity and reliability, and for other specialty applications.

LANtastic supports Windows95/98, Windows 3.1, DOS, OS/2 and Windows NT workstations.

Windows95/98 Networking

Well, it's better than Windows for Workgroups (but what isn't?). It's still the bottom of the barrel in peer-to-peer networking. Windows95/98 networking is the most used network today because it comes free in the Windows box and is pre-installed on just about every PC you can buy.

Windows95/98 networking offers NO meaningful security whatever. Its passwords serve no purpose except to allow customized desktops. An average 10 year old could probably figure out how to blow them away in about 15 minutes, but you don't even need to do that, just select "Cancel" at the password screen. Nearly all viruses infect Windows95/98, and can spread through the network almost instantly.

Windows95/98 networks are subject to Master Browser problems where workstations stop being able to see each other until the whole network is shut down. Network connections are easily lost by users and will have to be set up again whenever this happens. Not difficult, but annoying. Network performance is below average.

Microsoft has only one thing to say to people who have problems with Windows95/98 networking, "Get an NT/2000 Server". Automation Access says, "Get a Linux server".

Windows95/98 peer-to-peer networking supports Windows 3.1, Windows95/98, Windows NT and OS/2 workstations.

Wire & Cable

There used to be a lot of different network hardware and types of wiring (in fact, there still are), but today there is only one type of hardware and one wiring scheme significant to the small business office - ethernet 10/100 over Category-5 unshielded twisted pair. One 4-pair cable is run from each workstation to the wiring closet where the hub will live.

Please Note: this cable is extremely critical. No matter who actually pulls the cable it should be purchased from whoever is responsible for making the network work. That person must also approve the craftsmanship of the pull and connections. The alternative can be some big time charges for diagnosing and fixing problems.

We recently worked on a job where the network cable was already pulled by the phone guy before we were told of the move. He pulled two brands of cable. One of the brands didn't work with the network cards in the clients machines, and these cards had to be replaced.

On another job, we offered the phone guy some jacks to terminate the cable he was pulling, but he said he had enough. We plugged in the network and it didn't work, but the connect lights were all on. Turned out he used Cat-5 jacks at one end and Cat-3 jacks at the other, and wired them both the same. His terminations also came nowhere near meeting Cat-5 craftsmanship.

Whether your network will run at 10 Megabits/second or 100 Megabits/second or a mix of the two depends on the network cards and hub. Most current cards and hubs will automatically adapt. 100 Megabits/second requires Category-5 cable, while 10-Megabits will run on Category-3. Max run from card to hub is about 300 feet in either case.

Cable comes in two types, plenum and non-plenum. Plenum Cat-3 costs about the same as non-plenum, but Cat-5 plenum is still much more expensive than non-plenum. Your building or civil codes may require plenum cable, and if you use non-plenum the Fire Marshal can make you pull it out, so check before you pull.

Pulls must be kept away from fluorescent lighting fixtures and other sources of radio frequency noise, and must not have sharp bends or crimps.

We see many cases of cable pulled and terminated by people who don't know what they are doing. Never crimp RJ connectors directly to the ends of the cable. It may work now, but it is going to be endless trouble a few months down the road. Cables must be terminated to a proper 110 jack, 110 patch panel or 110 termination frame. Jacks need to be rigidly mounted, as in a wall plate or surface block to avoid flex - the wires break very easily. A Cat-5 patch cable goes from the jack to the computer. Same situation back at the hub - proper termination and patch cables.

Wiring scheme should be strictly EIA/TIA-568A or 568B (WECO) and don't mix the two - ever. We prefer 568B, which dominates in the U.S., 568A (the real standard) dominates in Europe. If someone tells you it doesn't matter what color pairs go to what pins as long as they are consistent, get him off the job right now! He doesn't know what he's doing and you're going to suffer for it.

©:Andrew Grygus - Automation Access - www.aaxnet.com - aax@aaxnet.com
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