What You Need to Know to Set Up a Small Ethernet Network
By Mel Beckman and Elizabeth Dougherty
If you're like many Macintosh users these days, your computer count is growing, especially if you're in a small business. There's the Main Mac, your 200MHz PowerPC pride and joy (strictly for work, of course); your partner's Main Mac 2; the Auxiliary Mac for the occasional temp; plus a PowerBook or two; and you're contemplating a Web server.
You can save time and money by connecting this collection, along with your peripherals, with an Ethernet network, which will let you easily share files and resources such as printers and an Internet connection. You might think a local area network (LAN) is only for big companies, but you can reap the advantages, too, if you're willing to spend a little time and money.
While the Mac's built-in LocalTalk connection makes it easy to connect devices, its 230.4-Kbps (0.23-Mbps) transmission speed pales next to Ethernet's 10 Mbps (or even 100 Mbps, if you want to invest the funds). Both the cost and the complexity of putting together an Ethernet network have been reduced so much that the benefits far outweigh the short-term expense.
In this hands-on guide, you learn what you need to construct your own Ethernet network: the parts, how they interrelate, how to avoid problems, and how much it costs. You can put together an Ethernet network for a handful of ma-chines for under $100. For most people, the 10BaseT type of Ethernet is the best to use, since it's easy to install and troubleshoot and uses the most prevalent wiring type.
With this article in hand, you will be able to sort through the dizzying array of network equipment (see the sidebar, "Picturing Your Equipment Options") in catalogs and computer stores and zero in on exactly what you need to start enjoying the benefits of being connected.
First, the Mac Connection
To attach a device to an Ethernet network, the device needs an Ethernet connector--either built in or via add-on hardware--into which you can plug the network cable. Here's what you need to know about the different kinds of connectors (to see what these look like, see the diagram "First, Determine the Right Connection").
Built-in 10BaseT
If you bought your Mac in 1995 or later, it may have Ethernet built in, in the form of a 10BaseT connector, which looks like an overgrown telephone jack (it has eight conductors instead of four). This is the best kind of connection because it connects directly to a 10BaseT cable without any extra hardware.
Built-in AAUI
Many Macs, especially older ones, have a connector type called AAUI (Apple Attachment Unit Interface). This requires a hardware adapter called a 10BaseT transceiver (about $35), a tiny box with a 10BaseT connector for the network cable and its own cable that connects to the Mac's AAUI port. You don't need any additional software.
Add-on Card
If your Mac doesn't have a 10BaseT or AAUI connector but has an expansion slot, you can add a 10BaseT connector via an internal card. Ethernet cards come in several varieties, including NuBus, PCI, Apple Communications Slot, PC Card, and LC (for the PDS slot).
You install the card just as you would any add-on card: following the instructions included with the card, you open your Mac, locate the card slot, insert the card, and button everything back up. Unlike the way it is in the PC world, there are no jumpers or switches to set on Mac cards--just plug and play.
Cards might require you to install driver software--read the documentation for requirements and check the vendor's Web site for the latest version.
Ethernet cards are commodities, costing as little as $70 (see the table, "Comparison Shopping for Your Ethernet Network"). Buy your cards from a reputable manufacturer--such as Asante Technologies, Dayna Communications, or Farallon Communications--that offers a warranty and good technical support.
External SCSI Adapter
For Macs without expansion slots, such as older PowerBooks, or when expansion slots are already filled, you need an external SCSI 10BaseT Ethernet adapter. The vendor will include any software you need. SCSI Ethernet adapters are expensive, around $200.
Second, the Right Cable
Whatever type of connector you have--a port in the back of your Mac, a transceiver, an add-on card, or a SCSI adapter--the goal is to get a place to plug in a 10BaseT cable, also called unshielded twisted-pair (UTP). You may hear about thick and thin Ethernet; avoid these obsolete technologies.
Here's what you need to know about buying cable.
Speed Rating
You want Category 5 cabling, the fastest possible (the scale is 1 to 5). The price difference between categories is not large, so don't consider buying anything less than Category 5. Look for the Category 5 or CAT-5 designation printed every few feet on the wiring's outer insulation. Another benefit to using Category 5 cable is that it will accommodate faster network speeds, including 100-Mbps Ethernet.
Length
Measure your work area, and buy terminated cable lengths that match the distances between devices as closely as possible. Keep in mind that Ethernet has distance limitations--practically, a maximum of 90 meters (about 300 feet).
Straight Through versus Crossover
10BaseT cables come wired straight through or crossover. You'll usually use straight-through cable; crossover cables are for special cases, such as connecting two devices directly.
To distinguish between types, hold the transparent connectors from both ends of the cable side by side with the same orientation. In a straight-through cable, wire colors inside the connectors match left to right; in a crossover cable, the color sequence differs.
Third, the Hub
In a 10BaseT network, you connect one end of the cable to the device and the other end into a hardware piece called a hub (also called a repeater). Just as the hub of a wheel connects all the spokes, a network hub connects all the devices of the LAN in what's called a star topology. In contrast, LocalTalk devices link sequentially, in a daisy chain.
The hub adds some expense (about $100 for eight ports) but connects multiple devices, regenerates data signals to improve reliability, and simplifies troubleshooting by isolating a failing device to prevent the whole network from crashing.
Here's what you need to know about buying a hub.
Choose Unmanaged
Of the two kinds of hubs--unmanaged and managed--you want unmanaged; managed hubs are expensive and have remote-control capabilities you don't need in a small LAN. Count the devices you want on your network and add two for growth--that's the minimum number of ports you need.
Common 10BaseT small-hub configurations have five or eight ports. There's not a big price difference, so don't scrimp--networks usually grow rather than shrink. Expect to pay between $10 and $20 per port. Make sure you count 10BaseT ports; one port is sometimes for connecting another hub or different cabling type.
Decipher the Lights
You'll want to know a little bit about troubleshooting, but the information that hubs provide can make it as easy as it is to check Print Monitor when you have a printing problem.
Every hub has status lights indicating whether a port is connected properly and when data is moving to the port. Other lights show if there's too much traffic or a failed device.
I find it easiest to monitor a hub that has the connectors and status lights on the same side of the box. However, you might want to have the cables on the back of the hub so they're out of the way. Just make sure you can easily see the lights to check for trouble.
As with cards and cabling, buy a hub from a reputable manufacturer that stands behind its warranty with good technical support. Online resources are key for getting quick help, so check out a vendor's Web site for online documentation, tutorials, and troubleshooting aids.
Bridge to LocalTalk
If you have LocalTalk devices, such as printers, that don't have an Ethernet connection, you can use a LocalTalk-to-Ethernet converter (some are just for printers), costing $200 to $300.
If you need to connect to LocalTalk Macs, you need a device called a bridge. However, a bridge is expensive, about $500 to $800. You can also use Apple's free LaserWriter Bridge (available at www.macworld.com/software) or $79 LocalTalk Bridge software to turn a Mac into a LocalTalk converter or bridge, respectively. Remember that LocalTalk devices connected to an Ethernet network this way are still limited to LocalTalk's slow speed.
A Hubless Alternative
If you're converting an existing LocalTalk network to Ethernet, or if centralized hub wiring is inconvenient, you might consider Farallon's hubless 10BaseT architecture called EtherWave, which uses 10BaseT cabling and proprietary adapter cards and transceivers (each with two 10BaseT jacks). EtherWave lets you daisy-chain up to eight devices LocalTalk-style.
EtherWave transceivers and adapter cards cost about twice as much as their hub counterparts. If you have AAUI-equipped Macs and need to buy transceivers anyway, the extra cost for EtherWave transceivers may be offset by the money you save not buying a hub. If you have some AAUI-equipped Macs, you can use EtherWave for those, but you'll still need a hub for Macs with only 10BaseT connectors. You can connect an EtherWave daisy chain to a 10BaseT hub.
Do the math. Generally, a hub is the cheaper option for Macs with 10BaseT built in, since two EtherWave transceivers cost more than a hub and two transceivers.
The Software Side
As long as you've installed any required drivers for adapter cards, System 7.5 and above has all the software you need for common networking tasks.
Transport Protocols
The Mac OS includes transport protocols, the software needed to move data over a network. The protocols you care about are AppleTalk and TCP/IP (which the Internet uses).
You should use Apple's current network architecture, called Open Transport (version 1.1.2 at this writing), which installs automatically with System 7.5 and is mandatory with System 7.6. Under System 7.5, you may have to enable Open Transport by running the Network Software Selector, found in the Apple Extras folder. (Apple has announced that it will maintain but not further develop Open Transport; instead it will use the OpenStep networking architecture in the new Rhapsody OS expected in mid-1998. However, that's not something to worry about right now.)
File Sharing
The Mac OS includes Personal File Sharing, which lets network users share data on hard drives in what's called peer-to-peer networking. For centralized file sharing, AppleShare server software, an extra-cost item, is necessary. You likely won't need AppleShare to accommodate data-sharing needs on a small LAN.
Connect and Test
Once you've connected all the hardware together, take the time to make sure every device can communicate with every other device and measure network throughput by timing how long it takes to copy files between Macs using Personal File Sharing.
Keep in mind that al-though 10BaseT theoretically transfers data at 10 Mbps, due to overhead you can only achieve about 60 percent of this speed. Data rates of 6 Mbps (750 KBps) are very good on fast Macs, and 4 Mbps (500 KBps) may be perfectly acceptable. Keep a record of your baseline network performance so you'll have a comparison point if you have trouble later.
The symptoms of problems can be as obvious as a nonfunctional network or as subtle as reduced performance or intermittent failures. Most protocols that run over Ethernet have built-in error detection and correction, and they will forge on in the face of severe transmission problems.
Make a Diagnosis
The status lights on the hub, adapter cards, and transceivers will help you diagnose a problem if trouble occurs.
*The link status light indicates that there's a proper electrical connection between a device and the hub in a hub-based network or between two devices in a hubless network. If this light is off, try replacing the cable; make sure you have the right type (straight through or crossover).
*The traffic light, sometimes labeled Activity or LAN, blinks when traffic is flowing. Better-quality devices have separate transmit and receive indicators (called TX and RX, respectively) to indicate the traffic direction. If you have a link indication but no traffic indications, suspect software misconfiguration or a failed hub, transceiver, or adapter card. Try swapping cables, then changing ports on the hub, to isolate the problem.
*The collision light blinks when there's too much traffic for the LAN to handle. A few collisions per minute are normal--these result when two computers try to transmit at the same time. Frequent (every few seconds) or continuous collisions may indicate wiring problems, such as damaged cables or corroded connectors. Try simplifying your network configuration to just two devices and the hub to isolate the problem component.
*The jabber light indicates that a device is transmitting noise onto the network. Jabber occurs when a device malfunctions and usually indicates that the device's Ethernet transceiver or card has failed. You can manually locate the failing device by disconnecting ports one at a time at the hub. When the jabber light goes out after you disconnect a particular port, you've identified the problem.
Wire Tangles
Most Ethernet problems result from bad or improperly wired cables. Buying ready-made cables designed for 10BaseT helps prevent problems. Still, you should have spare Category 5 cables for testing suspected wiring problems. Bad cable routing can induce noise in an Ethernet cable. Avoid routing cables in parallel with AC power lines, device power cables, or RS-232 printer cables.
Although you're not likely to reach 10BaseT's length limitations in a small office or home, it's easy to forget that 90-meter limit between hub and device. You can extend this limit by connecting up to three hubs in a series (follow manufacturer instructions for interconnecting hubs).
Macworld's Buying Advice
To take all the decision making out of network setup, consider buying a preassembled kit. For example, Dayna's Network Starter Kit provides everything you need for plug-and-play 10BaseT Ethernet: an eight-port hub, three PCI cards, three 50-foot Category 5 cables, and a step-by-step guide. At $289, this kit trims about $160 from the cost of separate components. However, the 50-foot cables are too long for most applications; ignore them and buy cables the right length for your space.
With its higher performance and low cost, Ethernet is a better choice than LocalTalk for small networks. Using quality components and avoiding common wiring errors are the secret to building a reliable LAN and enjoying the benefits of being well connected.
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Contributing editor MEL BECKMAN designs local- and wide-area networks and flies helicopters, but not at the same time.
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Sidebar
Picturing Your Equipment Options
A hub, such as Dayna's MiniHub-5, serves as a central connection point for devices on a 10BaseT network. The lights give you information such as whether a port is connected properly and when data is moving to the port. *** You use 10BaseT cable to connect your Mac to the hub. If your Mac doesn't have a built-in 10BaseT connector, you can add one using hardware such as an add-on card, like Asante's PCI card, or an AAUI transceiver. *** Farallon's EtherWave, a hubless alternative, uses 10BaseT cabling and proprietary adapter cards and transceivers (each with two 10BaseT jacks, pictured). EtherWave lets you daisy-chain up to eight devices.
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Sidebar
First, Determine the Right Connection
Whether you have a built-in port or need extra hardware--a transceiver or a card--to connect to a 10BaseT Ethernet network depends on the vintage of your Mac. Tip: to see if your Mac has a 10BaseT or AAUI port, look for the Ethernet connector symbol <--->. Here's what the three options look like.
AAUI Connection If your computer has an AAUI port, you need a 10BaseT transceiver, a tiny box with a 10BaseT connector and a cable that connects to the AAUI port. You can use either a standard transceiver or Farallon's EtherWave transceiver.
Add-in Card Required If your computer has no network port, you need add-on hardware, usually an internal adapter card like the PCI card shown here.
Next, Pick the Best Configuration
How you configure your network depends mainly on how many devices you have (and how many you plan to add) as well as their location.
The Simplest Network
Connecting two Macs, or a Mac and a peripheral such as a printer, requires a single crossover cable.
The Daisy-Chain Option
With Farallon's EtherWave, devices connect one to another in a daisy chain, rather than to a hub.
Hub-Centric Approach
A 10BaseT hub connects more than two devices in a star topology. Use straight-through cables.
August 1997
page: 120
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Copyright © 1997 Macworld Communications, Inc.
