LANs


Types of LANs
If you run wires between computers that are in the same office building, you're creating a
local-area network (LAN). Each computer in the LAN is called a node.
For the IBM PC and clones, you can create four kinds of LANs. Here they are, beginning with the
fanciest and most expensive.
Server LANs
A server LAN consists of a main computer (called the server) wired to several lesser computers
(called workstations).
A special person (called the network supervisor) tells the server how to act. Other office workers
(called users) sit at the workstations.
The server's hard disk contains a database that all the workstations can access. The server's
high-quality high-speed printer can print whatever the workstations tell it to.
If your network is too big to be handled by a single server, you can have several servers helping
each other, acting together as if they were one, big server. A server whose main chore is to handle
one of the network's big hard disks is called a file server. A server whose main chore is to handle a
printer is called a print server. A network can include several file servers and several print servers.
But the typical network has just one server that tries to do it all!
Each workstation uses MS-DOS (or Windows 3.1 or 3.11 or 95), but the server uses a different
operating system instead that runs faster. The server's operating system is called the network
operating system (NOS).
During the 1980's and early 1990's, the most popular NOS was Netware, which is published by
Novell. During the late 1990's, some companies switched to a new NOS, called Windows New
Technology (Windows NT), published by Microsoft.
If a NOS understands the same commands as the Internet (so you can access the info on the
server by giving Internet commands), the NOS is called an intranet, which means "a miniature
Internet for internal company use, with access restricted to company employees, and containing
info about just the one company."
Netware Novell has invented many versions of Netware. The most popular are Netware 3.12 (a
classic that uses DOS-like commands) and Intranetware 4.11 (a modern intranet that uses Internet
commands and Windows-like commands).
Here are the prices charged by discount dealers:
Number of users               Netware 3.12 price            Intranetware 4.11
price
                5                                                  $649                                                     $599
              10                                                 $1599                                                    $1386
              25                                                 $2339                                                    $2299
              50                                                 $3249                                                    $3029
            100                                                  $4529                                                    $4249
            250                                                                                                               
$7829
You can get those prices from discount dealers such as Network Express (1611 Northgate Blvd.,
Sarasota FL 34234, phone 800-374-9899 or 813-359-2876), Computer Discount Warehouse
(800-726-4CDW), and Data Comm Warehouse (a division of Micro Warehouse at
800-990-0748).
Netware can be complex. For example, the infamous version 2.15C came on about 40 floppy
disks, accompanied by 20 manuals! Newer versions let you do more tricks than earlier versions
and are slightly easier to install; for example, you can get version 4.11 on CD-ROMs instead of
floppies. But, the new versions are still hard enough so the typical office buying Netware pays the
computer store to send a technician, who comes to the office to set up the network. Traditionally,
the technician typically spends an entire afternoon to get the installation started, then leaves the
computer running overnight (while Netware spends several hours formatting the server's hard
disk) and comes back the next morning to finish setting up the network.
Computers The typical Novell network has slow workstations attached to a faster server.
In the early   1980's, the typical workstation contained    an   8088 CPU. The server
contained a 286.
In the late         1980's, the typical workstation contained    a           286 CPU.
The server contained a 386.
In the early   1990's, the typical workstation contained    a           386 CPU. The server
contained a 486.
In the late         1990's, the typical workstation contains     a           486 CPU.
The server contains a Pentium.
The server also contains a big RAM and a big hard drive. Now (in the late 1990's) the typical
server contains at least 32M of RAM and a 3-gigabyte hard drive.

Cables To form a Novell network, connect all the computers in the network by using cables.
Three kinds of cables have been popular.
The oldest kind is a thick, yellow, coaxial cable called thickwire Ethernet (or thicknet). It's also
called 10base5, because it can transmit 10 million bits per second and transmit those signals up to
500 meters (and up to 100 computers) without needing to have those signals boosted by a
repeater. Since the cable's diameter is 1/2-inch, it's too thick and stiff to bend around corners. It's
rarely used anymore.
Far more popular is a newer, cheaper, non-yellow coaxial cable that's thinner: its diameter is 1/5
of an inch. It's called thinwire Ethernet (or thinnet or cheapernet). It's also called 10base2, since it
transmits 10 million bits per second and transmit those signals "about 200 meters" (actually 185)
to 30 computers without needing a repeater. It bends around corners easily. The "cable" actually
consists of several 25-foot sections, joined together by joints called T connectors.
For example, here's how to set up a thinnet network that includes 11 computers (10 workstations
plus a server).
Buy 10 thinnet cable sections ($10 each). Join them together by using the joints (called T
connectors), so those 10 cable sections act as one long cable chain. Each joint is in the shape of a
T: the T's left and right prong each attach to a cable section; the T's bottom prong attaches to a
computer.
By using 9 T connectors (to connect the sections together) plus 2 extra T connectors (attached to
each end of the long cable chain), you can attach all 11 computers to the chain.
At each end of the chain is a T-connector that has an unused prong. Plug up that prong's hole by
attaching a $3 plug, called a terminator, which terminates the long chain.
The chain of cables is called a cable segment; it includes the 10 cable sections, the 11
T-connectors, and the 2 terminators.
Instead of using coaxial cables, the newest and most popular choice is to use just ordinary phone
wire - the same kind that the phone company uses inside the walls of your home, and which has an
RJ-45 connector on each end. Such a cable is called unshielded twisted-pair (UTP). It's also called
10baseT, since it transmits 10 million bits per second through a twisted pair. Here's how to set up
a 10baseT network:
Arrange the workstations in a circle. At the circle's center, put a box called a hub. Like a bicycle
wheel's hub, the network's hub has "spokes" coming out of it: each spoke is a 10baseT cable that
goes straight from the hub to one of the workstations. In addition to those spokes, one extra
10baseT cable comes out of the hub: that extra cable goes to the server, which is next to the hub.
Each 10baseT cable you use can be up to 100 meters long. (When you buy the cable, it comes on
a spool that holds 1000 feet of cable; you unroll the spool and snip the cable into shorter, usable
segments.)
To communicate with the server, the workstation sends a signal through its 10baseT cable to the
hub, which then passes the signal to the server.
That arrangement is called a star topology, since the hub looks like the center of a star, with each
workstation acting as one of the star's points. Out of the hub, many cables come out (one cable
for each workstation, plus one cable for the server), so the hub looks like an octopus.
The typical hub has 8 ports, to which you can attach 8 cables. You can buy a bigger hub, having
16 ports or even 24! For a small network, you can buy a cheaper hub have just 4 or 5 ports.
You can attach a group of hubs together, so the group acts as if it were one gigantic hub. To
attach 2 hubs together, run a 10baseT cable from the first hub to the second. To attach 3 hubs
together, run a 10baseT cable from the first hub to the second, then run a 10baseT cable from the
second to the third. To attach more than 3 hubs, attach all the hubs onto a thinnet cable instead.
If the folks sitting at the workstations don't like sitting in a circle ("star"), feel free to rearrange
the furniture! You can turn the circle into an oval, or even arrange all the workstations in a row.
No matter how you rearrange, the setup is still called a star topology, since the computers can't
tell the difference: just make sure each workstation still has its own cable going directly to the
hub.
You can even put the hub in a different room, if you run the cables through the wall. Then plug
each computer into the wall, using an RJ-45 jack (similar to a jack for plugging in a phone).
10baseT is more reliable than the other cabling methods, because a 10baseT cable failure affects
just the workstation it's attached to. For the other cabling methods, a failed cable shuts down the
entire network.
Network cards Into each of the network's computers, you must insert a network interface card
(NIC). It's a printed-circuit card to which you attach the network's cable. A plain, simple NIC
costs about $25; fancier NICs (which go faster and have extra connectors) cost about $100. The
NIC is also called an Ethernet card, even if you're using 10baseT cables (since 10baseT cabling
act as a cheap imitation of Ethernet cabling).
How the network works Each user sits at a workstation. When the user turns on the workstation's
power, the workstation asks for the user's name (and maybe a password). Typing the name and
password is called logging on to the network.
After the user logs on, the user's workstation accepts normal MS-DOS commands, just as if the
user weren't on a network.
For example, if the workstation contains two floppy disk drives, they're called A and B, and the
user can find out what's on drive A by typing "dir A". If the workstation contains a hard drive,
that drive is called C. But if the user tells the workstation to get a file from "drive F", the
workstation will get that file from the server's hard drive, by using the network. The server is
everybody's "drive F". For example, to find out what files are on the server, the user gets a
directory of those files by typing "dir f".
Passwords and other security measures prevent any individual user from messing up the important
files on the server. The network also prints reports saying how much time each user has been
spending on the network.
That's how the typical Novell network acts, but your Novell network might be set up to use a
different letter than F. If the letter F bothers you (because it reminds you of sex), you can set up
the network so that the server's hard disk is called "G" instead.
Total cost To create a 25-user Novell network, you face many costs.
First, buy Intranetware (for $2299). Next, spend many thousands of dollars to buy a server and 25
workstations. For those 26 computers, buy 26 network cards, cables, and either T-connectors or
hubs. Pay several thousands dollars for the labor of installing Netware on the server, fiddling with
each workstation's AUTOEXEC.BAT, inserting the 26 network cards, stringing the cables so
nobody trips on them (you might have to punch holes through your office's walls and floors!),
buying network versions of all the programs you want to use on the network, and training all the
users.
Hey, nobody said progress was cheap!
Since installing a Novell network is so expensive, don't do it unless you have no other choice.
Let's look at cheaper alternatives....

Peer-to-peer networks
A peer-to-peer network is a network in which more than one computer can act as a server. In a
peer-to-peer network, every computer can be given the ability to send files directly to every other
computer. Since each computer runs ordinary MS-DOS (instead of a special server DOS such as
Netware), the network runs more slowly than a server network but is more flexible.
The best and most popular peer-to-peer network is Lantastic, invented by Artisoft. Lantastic
comes in three versions.
The fancy version uses thin Ethernet cables and Ethernet network cards - just like Novell. But
instead of using a "server" and Netware, it uses the Lantastic operating system, which is much
easier to install (it comes on just one floppy disk!) and costs less.
Discount dealers sell a 2-user starter kit for about $500. That price includes the Lantastic
operating system, networking hardware (thin Ethernet cables, terminators, and Ethernet network
cards), and manuals to hand the 2 users. Your only additional expense is the labor of installing it
all, which is easy!
Ethernet transmits data at a speed of 10 megabits per second. (That's 10 million electric signals
per second.) If you don't need that much speed, you can save money by getting a
2-megabit-per-second version of Lantastic; its 2-user starter kit costs just $359.
Zero-slot LANs
To cut your cost even further, get a LAN that doesn't need a network card - and therefore doesn't
need a slot to put the network card into. That kind of LAN is called a zero-slot LAN. To attach
the LAN's cable to the computer, plug the cable into the computer's parallel printer port or
RS-232 serial port.
Unfortunately, a zero-slot LAN handles just one pair of users - just 2 computers. The hardware
setup is so easy: just run the cable from one computer's port to the other computer's port!
The most popular zero-slot LANs have been Lantastic Z and Desklink. Discount dealers sell each
for about $90.
Desklink comes with a serial cable (to plug into the serial ports). Since the main part of the serial
cable is an ordinary phone cord, you can run Desklink even between computers that are many
yards apart: just buy a longer phone cord or an extension cord from your local phone store (such
as AT&T or Radio Shack). Unfortunately, it works slowly: just 0.1 megabits per second.
Lantastic Z uses that same kind of serial cord (at the same speed) but also includes an 18-foot
parallel cable, which you can use instead for faster transmission. But even if you use the parallel
cable, the transfer rate will be much slower than the network-card versions of Lantastic.
Instead of buying Desklink or Lantastic Z, you can get a zero-slot LAN free! MS-DOS 6 (and 6.2
and 6.21 and 6.22) include a zero-slot LAN program called "interlink" (but spelled Interlnk).
Windows 95 includes a zero-slot LAN program called Direct Cable Connection (DCC). To use
Interlnk or Direct Cable Connection, just buy a cable and you're all set - except for learning how
to use it. (On the next page, I explain how to use Interlnk. Direct Cable Connection is more
tricky: you try accessing it by clicking Start then Programs then Accessories then Direct Cable
Connection, but that part of Windows 95 might not be installed on your hard drive yet; and even
if it is on your hard drive, it's tricky to set up properly.)
File transfer programs
To pay even less, get a file transfer program. The most popular one is Laplink, from the makers of
Desklink. Discount dealers sell it for just $99. It includes a universal cable that you can attach to
either serial or parallel ports.
Even easier to use than Desklink, Laplink is a program that shows you which files are on each
computer's hard disk and lets you copy files from one computer to the other. Laplink's only
purpose is to copy files. If you're sitting at computer A and you want to run a program on
computer B's hard disk, Desklink lets you run it immediately; Laplink requires that you copy the
program to your own hard disk first.
Good dealers
If you're near Boston and want to install a Novell or Lantastic network, you can get help from a
dealer called Aegis (in Watertown at 617-923-2500). The Aegis employees are friendly and
competent. They usually charge just $65 per hour.
Another Boston-area company to explore is Synaxis (in Needham Heights at 617-449-4400). It
has more experience and knowledge about setting up big Novell networks for law offices and
banks. It charges about $90 per hour.
For advice about setting up big Novell networks for law offices, phone Krantz-Woodland
Technologies (KWT) at 617-266-1031. It's a consulting company that gives good advice about
how to save money and grief when buying and installing computers, networks, and law software.
It operates from the home of Roy Krantz, who's an old buddy of mine. He's taught many courses
with me. In his previous life, he founded a company called "Digicom Computers", which merged
into "Compuware Services", which changed its name to "Synaxis", from which Roy departed to
found Krantz-Woodland Technologies.
If you're in another part of the world, ask around to find the best network dealer near you. If you
have any experiences to share, please tell me!

Interlnk
MS-DOS 6 includes a program called Interlnk, which lets you create a zero-slot LAN without
buying extra software. That program is part of MS-DOS 6 (and 6.2 and 6.21 and 6.22) but is not
part of Windows 95 (or DOS 95).
Here's how to use Interlnk to let two computers communicate with each other.
String the cable
Buy a bi-directional 25-pin male/male parallel cable.
It has 25 pins sticking out of each end, so each end can plug into a computer's parallel printer
port. You can get it at your local computer store for about $10. You can also get it mail-order for
$6.15 (plus $2.95 handling) from Cables America (by phoning 800-FIT-USA4 and asking for
cable #126349A).
Turn both computers off. Unplug any printers (and their cables) from the computers.
Attach one end of the bi-directional cable to the first computer's printer port. Attach the other end
of that cable to the other computer's printer port.
Prepare the server
The computer whose hard disk contains most of the files is called the server. For example, if
you're transferring files between a notebook computer and a desktop computer, the server is the
desktop computer, since it contains most of the files.
Turn that server computer on, so you see a C prompt.
Type "intersvr" (which is short for "Interlnk server"), so your screen looks like this:
C:\>intersvr
When you press the ENTER key at the end of that line, the computer will say "Microsoft Interlnk
Server".

Prepare the client
After you've prepared the server, turn on the other computer (such as your notebook computer),
which is called the client.
Make sure the bottom line of the client's CONFIG.SYS file says this:
device=dos\interlnk.exe
(To check whether that's the bottom line, say "type config.sys".) If that's not the bottom line, do
this:
Type "edit config.sys".
Move to the bottom of CONFIG.SYS by doing this: press the END key while holding down the
Ctrl key.
Type "device=dos\interlnk.exe".
Finish editing by doing this: tap the Alt key, then the F key, then the X key, then the ENTER key.
Reboot the computer by doing this: while holding down the Ctrl and Alt keys, tap the DEL key.
If the computer says "not enough drive letters", don't worry about that message. It just means that
your extra devices (such as your CD-ROM) won't work while Interlnk is running.
Let the client control the server
After peparing the server and the client, sit at the client computer and give any DOS command
you wish. You can talk about:
"a:" (the client's main floppy drive)
"b:" (the client's second floppy drive, if any)
"c:" (the client's hard drive)
"d:" (the server's main floppy drive)
"e:" (the server's second floppy drive)
"f:" (the server's hard drive).
For example, to find out what's on the client's hard drive, say "dir c:" (or just "dir"); to find out
what's on the server's hard drive, say "dir f:".
The computer adjusts those letters if necessary. For example, if the server doesn't have a second
floppy drive, the server's hard drive is called "e" (instead of "f:"). If the client has two hard drives
("c:" and "d:"), the server's main floppy drive is called "e:" (instead of "d:") and other drives are
called "f:", "g:", etc.
Interlnk assumes the server has no more than 3 drives. If the server has 4 drives, Interlnk uses just
the first 3, unless you insist on 4 by changing the client's CONFIG.SYS line to this:
device=dos\interlnk.exe /drives:4
If MARY is a file on the server's hard drive "f:", you can copy it to the client's hard drive by
saying:
C:\>copy f:mary
If SARAH is a folder on the server's hard drive "f:", you can copy it to the client's hard drive by
saying -
C:\>md sarah                                                     makes,
on drive C, a new folder called SARAH
C:\>copy f:sarah sarah                       copies everything from drive F's
SARAH to drive C's SARAH
or by saying:
C:\>xcopy f:sarah sarah\                In the xcopy command, the "\" creates a new
folder if necessary.
If SARAH is a server folder that contains other folders in it, you can copy it and all its inner
folders by saying:
C:\>xcopy f:sarah sarah\ /s/e In the xcopy command, the "/s/e" copies all subfolders.
To copy all unhidden files from the server's hard drive to the client's, say:
C:\>xcopy f: c: /s/e
But beware: that command copies all the server's unhidden files (even CONFIG.SYS,
AUTOEXEC.BAT, all of DOS, all of Windows, and all drivers for the mouse, CD-ROM, and
other devices) and destroys versions that were on the client previously.
Break the connection
When you finish using Interlnk, do this to the server's keyboard: while holding down the Alt key,
press the F4 key. That tells the server to stop running the intersvr program.
Finally, if you don't plan to use Interlnk anymore today, do this:
Erase the Interlnk line from your CONFIG.SYS file (or put the word REM at the beginning of
that line, since the computer ignores any line that begins with REM).
Turn both computers off.
Remove the bidirectional cable. Reattach the printers to the computers.

Classic Netware commands
Here are more comments about using Netware's classic version (3.12).
Getting started
Put network interface cards into all the computers and run cables between them. Then install
Netware on the file server (by following the instructions in the Netware manual). Then install the
client disks (included with Netware) onto each workstation. Finally, the network administrator
sits at the console (the server's keyboard) and runs the SYSCON program, to create a user login
for each person who will use the network.
User commands
These commands can be typed by any user sitting at any workstation or at the server.



Command you type                                       What the computer
will do for you
F:\>login chris     ask for your password (if any) to verify that you're Chris, then connect you
to the server
F:\>logout     cancel the "login"; disconnect you from all file servers
F:\>whoami     tell you who's been sitting at this workstation (the person's name), when the person
logged in, which workstation this is, which server the person is connected to (if the network has
more than one server), and which version of Netware is being used
F:\>send "Let's eat" to ann   immediately send a message to another user, named Ann, telling her
"Let's eat"; after Ann sees that message on her screen, she must press the ENTER key while
holding down the Ctrl key, so she can continue working
F:\>castoff    "turn broadcasts off"; prevent other users (and the network administrator) from
sending you any messages, and thereby prevent anybody from interrupting your work
F:\>caston     cancel the "castoff", so broadcasts are turned back on and other users can send
you messages again
F:\>capture q=laser ti=10     from now on, send any printed output to the network's main printer
(called "laser") instead of to your workstation's printer; if the network's main printer is unavailable
(because it's being used by somebody else), your request is put in a waiting line (a queue); the
"ti=10" means: if your program sends no print commands for 10 seconds, that 10-second pause
marks the end of your print job; your entire print job will be printed in one batch, without
interruption from other users
F:\>endcap     cancel the "capture", so any future printing will be done on your workstation's
printer, not the network's main printer
F:\>ncopy poem.doc poem2.doc  make a copy of the file POEM.DOC (which is on the
server), and call the copy POEM2.DOC (which is also on the server); the "ncopy" command
resembles DOS's "copy" command but runs faster, since "ncopy" does all the copying directly on
the server without copying the file to the workstation's RAM
F:\>flag payroll.exe sro make the file PAYROLL.EXE be shareable (so several people can
use it at the same time) and read-only (so nobody can destroy it or alter it)

Administrator commands
To type the following commands, you must be sitting at the server's keyboard (the console) and
be the network supervisor (or some other high-level administrator):

Command you type              What the computer will do for you
:broadcast Let's eat     immediately send a message to all users, telling them "Let's eat"; after users
see that message on their screens, they must press the ENTER key while holding down the Ctrl
key, so they can continue working; this message will not be seen by users who said "castoff";
before shutting down the server, broadcast a message saying "The network will shut down in 5
minutes. Please log off now."
:disable login prevent additional users from logging in to the server; give this command if
server's getting overloaded or you want to shut down soon
:enable login  cancel the "disable login", so additional users can log in to the server
:down     shut down Netware, so you can turn off the server safely; before giving this command,
make sure all users have logged out
:exit     return the server to DOS, so you see a DOS prompt & can give DOS commands; before
giving this command, give the "down" command

Other ways to share
Instead of buying a LAN, try these cheaper ways to share....
Sharing a printer
Suppose you and a colleague want to share a printer. Instead of buying a LAN, just unplug the
printer's cable from one computer and reattach it to the other computer!
If you're too lazy to unplug the printer's cable, another alternative is to buy a box called an AB
switch box, which most dealers sell for about $15. Into the box, plug the printer's cable and two
cables (called "A" and "B") that go to the two computers. The switch box has a switch on it; if
you flip the switch to position A, electricity flows between the printer and the computer attached
to cable A; if you flip the switch to position B instead, the printer is electronically attached to B's
computer.
To let four people share a printer, get an ABCD switch box, which attaches the printer to four
computers called A, B, C, and D. Dealers sell it for about $20.
Hewlett-Packard, which makes the most popular laser printers, warns you that traditional switch
boxes generate surges that damage laser printers. When switching, avoid damage by turning the
laser printer off - or turning it off-line. Better yet, instead of using a traditional (mechanical)
switch box, use an electronic switch box, which has no mechanical switches and doesn't generate
any surges. The cheapest ones cost about $75.
But during the last few years, printer prices have dropped dramatically! Now you can buy a laser
printer (such as the Okidata Page 4W) for just $269, and you can buy an ink-jet printer (such as
the Canon BJC-240) for just $179! At those new, low prices, your best bet is to buy a separate
cheap printer for each computer and forget the hassles of switch boxes and networking!
Sneaker net
Of all the networking schemes ever invented, my favorite is sneaker net, because it costs the least.
To transfer data to your colleague's computer by using sneaker net, just copy the data onto a
floppy disk, then put on your sneakers and run with your floppy to your colleague's desk!
That method is also called the Nike net. In Boston, it's called the Reebok net. Besides being free,
it's also the healthiest network for you, since it gives you some exercise!
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Communication: local-area networks

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Communication: local-area networks



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