In the past, Yale public cluster and College room connections used LocalTalk exclusively to connect to Yale Spine, the Yale network's ethernet backbone. Now that ethernet is available in clusters and Colleges, we will probably see LocalTalk fade into computer history as we upgrade from our LocalTalk-only Macintoshes to Ethernet-capable machines.

• Ethernet vs. LocalTalk

• LocalTalk Connections

  Hardware Installation

  Software Installation

  Software Configuration

• LocalTalk Daisy Chains
• Testing LocalTalk Jacks
• Docking Stations

• Setting up File Sharing
• Ethernet

The difference between Ethernet and LocalTalk can be stated simply: LocalTalk is slow and cheap, Ethernet is fast and expensive. The hardware cost of LocalTalk is ~$20, versus Ethernet's cost which can range from $50 to $240. The highest speed LocalTalk can reach is 230 kbs, much slower than Ethernet's 10 Mbps. Neither protocol actually reaches these performance maximums, network traffic and computer overhead greatly reduce the data rate. Nevertheless, Ethernet is noticably faster than LocalTalk.

A more important distinction between the two protocals is the amount of support each has in the world of IBM-compatible computers. Apple's LocalTalk networking standard is not widely accepted by PC users, this has made it is more expensive than ethernet, whose extensive acceptance and varied third-party support has forced prices down. There is better operating system-level support of Ethernet on IBM-compatible computers than LocalTalk, and many more utilities and software applications that can take advantage of the faster standard.

Macintoshes have always had on-board hardware and included system software to support LocalTalk. The MacOS has supported Ethernet since 1987, but built-in Ethernet hardware only made its appearance a few years ago. Most Macintosh computers sold today have "built-in Ethernet" in addition to the LocalTalk standard (low-cost models usually do not have built-in Ethernet). "Built-in" is a somewhat misleading term; while the ethernet hardware is in fact on the motherboard, an external "tranceiver" (much like a teleconnector for LocalTalk) is required to mediate between Ethernet's 10base-T wiring and the Ethernet port. Adding Ethernet to older Macintoshes without "built-in Ethernet" can be prohibitively expensive, particularly for PowerBooks. Newer Macintosh models are including 10base-T ports directly on the motherboard, providing true built in ethernet without the need for a transceiver.

With the resistor in one of the teleconnector's jacks (there is no difference between the two), plug one end of the phone wire into the other teleconnector jack and the other end into the wall jack. The short serial cable at the other end of the teleconnector should be plugged into the serial port with the printer icon above it (shown below). The completed setup is diagrammed below:

Printers and file servers on a LocalTalk network sometimes disappear from the list of available devices in the Chooser. If this occurs, first verify that the devices are plugged in, turned on, and properly connected to the network. If the devices still do not appear in the Chooser, there may be a "ghosting" problem. There are several possible causes for ghosting:

1. The total length of your network cabling may be too long, Weakening the signal reaching your Macintosh from the ghosting devices. Do not exceed the published maximum cable lengths. For Apple LocalTalk and Fallaron PhoneNet cabling, the maximum is 1000 feet. Cable length should not be a problem on the Yale network unless there is an extremely long daisy chain.
2. The second cause of ghosting can be reflections in the signal. Reflections are like electrical echos. They can cause serious communications problems. Small reflections are caused by changes in impedance (resistance) in the wire along its length. You can have changes in impedance when the network wire changes from one wire type to another or from one wire gauge to another. It can also happen when there are kinks in twisted-pair wire. Large reflections occur when a wire has not been properly terminated. This will almost always cause problems. Verify that your network cabling is in good condition, you have no loose network connectors, and that the network is properly terminated.
3. The third possible cause of ghosting is exceeding the maximum number of nodes (devices) on the network. For LocalTalk, the maximum number of nodes is 32. Again, this should not be a problem on the Yale network.

Network Control Panels:

Network

MacTCP (needed for TCP/IP protocols)

Sharing Setup

File Sharing Monitor (needed for File Sharing)

Users and Groups (needed for Personal File Sharing)

Network Extensions:

AppleShare

Network Extension

Apple Built-In Ethernet (needed for Ethernet)

EtherTalk Phase 2 (needed for Ethernet)

File Sharing Extension (needed for Personal File Sharing)

Networking also requires that certain resources be in the system file.

LocalTalk Daisy Chains

A simple LocalTalk network can be one computer connected to a printer, or two computers connected together. LocalTalk connects computers in a "Daisy chain", one network device is plugged into another, forming a long line of devices:

The ends of the chain must be terminated (using a resistor RJ-45 plug for teleconnectors), and cannot be joined to make a circle.

The simplicity of LocalTalk is complicated by one of its limitations: Only 32 devices can be connected in any one chain. Large LocalTalk networks like the Yale network are created by using StarControllers and Gatorboxes to branch chains from chains until there are enough available nodes to put at least one jack in each room. The Yale network is actually a lot more complex than a simple branched chain, Yale Spine provides a fast ethernet backbone off of which network routers create zones and other connections, and most room connections are connected to Star controllers.

In some cases, it is necessary to daisy chain two LocalTalk devices together:

• Most rooms only have a single LocalTalk jack, but there might be two computers to be networked. In this case, one of the computers will connect to the wall jack as usual, but the other computer will connect to the first computer's teleconnector as if it were a wall jack. The first computer's teleconnector will not be terminated (one phone cable going to the wall, another phone cable going to the second computer's teleconnector), but the second computer's teleconnector must have a terminating resistor. Neither computer needs to be on for the other to operate.
  
• Some users will have networkable printers that they wish to connect to the network for remote printing. Networkable printers act like any other network device, and daisychain exactly as if it were a second computer. ACS does not charge a network fee for printers.
  

If you have determined that the problem lies with the wall jack, you can test the jack in one of two ways:

1. Borrow a JackTester from the Connecticut Hall Network Center (CHuNC) closet. The tester only needs to be plugged into the wall jack in question while the button is pressed. If the LEDs illuminate, the wall Jack is active (the Jack tester's lights indicate network traffic). Make sure the JackTester's battery is okay by first testing a working LocalTalk wall jack.
2. Borrow the PowerBook from the Connecticut Hall Network Center (CHuNC) or another colleuge (or use your own). Plug the PowerBook into the LocalTalk Wall jack in question with a working teleconnector and open the chooser. Make sure the PowerBook's Network Control Panel is configured properly and that AppleTalk is on. Open the Chooser and check for zones (indicating an active wall jack).