Getting your machines to communicate
This article is not intended for those of you that already have a large office network. It is intended for computer users-of PCs or Macs-who have more than one computer in the same location, but have never connected them together.
We'll look at several different methods of getting your machines to talk to each other, and look at what you can do once you've got a network happening.
The null solution
The smallest and simplest network is simply two machines connected via a direct cable. In the old days, this was commonly accomplished using what was known as a "null modem."
Each computer ran a terminal program (i.e., telecommunications software) and the null-modem cable made the computers act as though they were each communicating via modems, except that no telephone line was required and the speed of the null-modem connection was much higher.
These days, the principle is the same. Cables are available for direct serial-to-serial connections, or a null modem may be purchased for a few dollars to connect two standard serial cables.
The big difference is that programs such as Traveling Software's LapLink, Symantec's pcAnywhere, or Microsoft's Direct Cable Connection facility in Windows 95 can allow computers connected via a direct-cable connection to behave as though they were shared on a network.
In other words, the other computer's hard drive, printer, CD-ROM and/or other resources become available to the "remote" user.
LapLink and pcAnywhere, it must be said, have a plethora of other features that add to their usefulness. We know of network administrators who swear by the Symantec product for its ability to let them remotely log onto a user's machine, diagnose and fix problems.
This capability can save a large organization a great deal of money and probably explains why Symantec says its pcAnywhere products currently account for 20 percent of the company's overall sales.
LapLink, as its name implies, got its start as a tool designed primarily to allow the easy transfer of files between a laptop and a desktop PC. It has evolved into a program with similar functionality to the Symantec product.
Farallon's Timbuktu also offers remote diagnostic and remote-control capabilities and is the only one of the three programs that offers a Macintosh version of the software, allowing, among other things, the remote control of a connected PC from a Macintosh workstation.
All of these products can work via a direct connection, or over a modem or network.
Simple Local Area Networks
A notch up from a direct-cable connection would be a small workgroup of networked computers, connected using one of several so-called "peer-to-peer" networking methods.
Windows for Workgroups, LANtastic, Windows 95, OS/2 Warp Connect, Macintosh System 7.x, and numerous other solutions exist in this area and all are relatively simple to set up and use.
The basic concept of a peer-to-peer local area network (LAN) is the same as with a direct connection: once connected, other users' hard drives, printers, CD-ROMs and/or other resources become available to others in the group.
The main difference is that peer-to-peer networks are able to support more than the two (or sometimes three) computers it is possible to connect via a direct-cable connection.
Moreover, the peer-to-peer network is a "real" network, in that you need a network interface card on each computer that you want to connect. (But keep in mind that the distinction between network card-based peer networks and those that use a direct connect cable are blurring because of the added functionality of LapLink-type software mentioned previously.)
Probably the simplest computers to network are Macintoshes, which have, since their inception, included built-in networking functionality.
Mac Networking
At the most basic level, two or more Mac users can simply connect their computers via so-called LocalTalk cables and then every user in the group can print to a shared printer on the network, or, with the file sharing software in System 7.x or later, share files on each other's hard drives.
Some newer Macs have Ethernet (a relatively fast type of network interface) built in. Older Macintosh models include a slower network interface called AppleTalk -- a few models have both. AppleTalk can transfer data at a few hundred kilobits per second; EtherTalk (Apple's name for its Ethernet networking functionality) can transmit up to 10 megabits of data per second.
Windows Networking
Windows users looking to network two or more PCs should refer to the article entitled HOW TO NETWORK TWO COMPUTERS at http://duxcw.com/. This easy to understand site has everything for do-it yourselfer.
Alternative platforms, such as Linux, FreeBSD and other non-Windows systems behave similarly. Generally speaking, the two computers have to be set up with the same protocols, on the same subnet, and share the same workgroup name. www.practicallynetworked.com has additional details.
What is Ethernet?
Ethernet is a networking specification that defines cabling and signalling parameters. It was originally developed by Xerox in the 1970s, and further developed by Digital Equipment Corp., Intel and Xerox through the '80s.
Ethernet has become the most popular method of networking PCs. Ethernet interface cards are available for as little as $50, and a group of Ethernet-equipped PCs running Windows for Workgroups, Windows 95 or OS/2 Warp Connect gains similar functionality to the above-mentioned Mac scenario without much more effort.
There are a few caveats when setting up an Ethernet network. First, there are different kinds of Ethernet connections: coaxial, also known as thin Ethernet, is a round connector that vaguely resemble a TV's cablevision connector.
Computers connected via this "coax" cable require what is known as a terminator on each end of the network chain.
Typically, the coax cable is connected to a "T"-shaped connector, in which one of the three ends connects to the card, the coax cable goes on another end (connecting, in turn, to another computer), and the third connector has either a second coax cable (to connect a third PC) or a terminator on the other end.
In other words, no matter how many computers are networked together in this "daisy chain" fashion, two terminators are always required (one at each end of the chain); otherwise, the network just doesn't work.
When you get more than a few computers connected in this way, one of the disadvantages becomes obvious. Like a string of Christmas lights, where one bulb fails and they all go out, a daisy-chained Ethernet network is prone to failure if any machine on the network suffers cabling or interface card problems.
To address this issue, many small offices (or work groups within a larger network) employ what is known as a hub-a small box that, as the name implies, becomes the center to which all the computers of the network or workgroup are connected. Each computer is connected to the hub in a star configuration, so that the failure of any machine(s) doesn't affect the others.
Naturally, there are many other network configurations possible, and a complete discussion of networking topologies is beyond the scope of this article. Fortunately, numerous Frequently Asked Questions lists (FAQs) about networks-and practically any other topic you care to know about-are available on the Internet. For example, try this site:
www.smartpages.com/faqs/LANs/ethernet-faq/faq.html
One thing we discovered from reading these FAQs is that it is possible to build a "crossover box" that allows the use of inexpensive 10BaseT (also known as "twisted pair") cabling to connect two or more computers with 10BaseT-type Ethernet interfaces together.
(It is also possible to purchase or build a special crossover cable, sometimes called a "null cable," although you must make sure that it does not get mixed up with standard 10BaseT cabling. So label that cable!)
The 10BaseT type of Ethernet card is popular for several reasons, but there is one big advantage: the cabling (which resembles telephone wire, complete with a slightly oversized facsimile of a modular phone-jack connector on each end) is considerably less expensive and less bulky than coaxial cable.
Some Ethernet cards have only the earlier-mentioned coax connector; some have a 10BaseT connector; some have both coax and 10BaseT interfaces, and a few also have a large D-shaped attachment interface called-wait for it-an attachment unit interface, or AUI.
Faster standards
Faster Ethernet standards exist, too, including the 100VG AnyLAN standard and the so-called Fast Ethernet 100baseT standard. Although 100baseT seems to be more popular, proponents of 100VG can lay claim to a superior technology.
They point to the problems 100baseT Fast Ethernet has with collisions of network data-a problem that 100VG avoids with "round-robin" access. On a high-end system, greater throughput (up to 100 Mbps) is possible with 100VG than with 100baseT.
Interface cards
We have not noticed a significant difference between the performance or reliability of low-cost versus high-priced Ethernet cards of similar types (e.g., 100baseT Ethernet). At this point, we usually install inexpensive D-link or Realtek PCI Ethernet cards into computers, and they invariably work flawlessly. Older ISA cards are more problematic.
Depending on the machine and the network cabling, you may need a specialized card. Some, for example, provide both thinnet (thin Ethernet) and 10BaseT connectors. Some operating systems have specific compatibility requirements (an NE2000-standard network card is usually a safe bet); some Mac models require unusual external connectors known as AUA attachments.
Generally, look for a card that does not need manual configuration by jumpers on the card or by software commands. On modern operating systems, most PCI Ethernet cards are completely "plug-and-play."
Internet Connection Sharing
We generally prefer hardware routers to software-based Internet connection sharing solutions. A basic router costs less than $100; wireless-capable models run about double that price. See our articles on wireless networking elsewhere in this section for details.
PC Card interfaces
If you are using a portable computer, you may need to purchase and install a PCMCIA (PC Card) Ethernet interface, allowing your portable computer to connect to an office or home LAN. PCMCIA cards, in case you're not familiar with them, are about the size of a credit card, and three or four times as thick.
Portable computers typically have one or two slots able to accept these cards, and a wide variety of PC Cards are available to add various functions (networking, modem, sound, SCSI, etc.) to virtually any laptop PC.
We tested Ethernet PC Cards by Fujitsu, Megahertz and Xircom. Most major brands work well under recent versions of Windows and Linux. Generally, avoid products not specifically claiming compatibility with your operating system of choice.
Some models sport an external "dongle" to which you connect your Ethernet cable; others have a built-in jack that pops out or is otherwise built into the adapter. We prefer the built-in type.
As is the case with PCI cards, you can also find models for specialized needs: some include both 10/100BaseT and coaxial connectors.
Our favorite adapters provide status lights that show network activity-a helpful diagnostic feature. Avoid cheap network interfaces that lack status indicators, and be sure to check that your network type and operating system are supported by the drivers supplied with the card.
For Further Reading
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