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LocalTalk Bridge 2.1 Document and Software

This article has been archived and is no longer updated by Apple.

This article contains a software link to LocalTalk Bridge version 2.1.

LocalTalk Bridge 2.1 Information

The Apple LocalTalk Bridge is an unsupported tool used to share LocalTalk-only devices, such as some LaserWriter printers, PowerBook notebook computers, or Newton MessagePad communications devices on an Ethernet, Infrared, or Token Ring network. With the LocalTalk Bridge, you can access an Ethernet, Infrared, or Token Ring network while maintaining a seamless connection to your LocalTalk network. Again, this is an unsupported tool and has been provided solely as a convenience. Apple makes no warranty or representation, express or implied, with respect to this program, its quality, performance, or fitness for a particular purpose.

System requirements for the LocalTalk Bridge

System software version 7.1 or later.

Either classic AppleTalk networking software or Open Transport version 1.1 or later. For machines running Open Transport, version 1.1.2 or later is recommended.

Memory requirements:

  • The LocalTalk Bridge driver requires approximately 70K of RAM to run.
  • Open Transport requires a minimum of 5 MB of RAM for computers with 68000-family microprocessors or 8 MB of RAM for computers with PowerPC microprocessors. Open Transport memory requirements are based on total system memory including virtual memory, minus the size of any RAM disk and disk cache you choose.

Installing the software

The following installation procedure directs you through both a new installation and updating an existing installation of the Apple LocalTalk Bridge:

  1. Drag the LocalTalk Bridge icon onto your computer's System Folder icon and release the mouse button before the System Folder automatically opens. The LocalTalk Bridge will be automatically installed in the Control Panels folder inside your computer's System Folder. If you get a message indicating that an older version of the software already exists in this location, click Replace.
  2. Choose Restart from the Special menu.

When your computer starts up again, the LocalTalk Bridge is installed.

Description

The Apple LocalTalk Bridge is an unsupported control panel that bridges a LocalTalk network to another network selected from the Network or AppleTalk control panels. This solution allows for connectivity to higher-speed networks (for example, Ethernet, Infrared, or Token Ring) while maintaining the ability to print to LocalTalk-only LaserWriter printers or share files with PowerBook computers that lack high-speed network capabilities. Similarly, when connecting to an Ethernet- or Token Ring-only network, the LocalTalk Bridge provides a way for LocalTalk-only PowerBook computers or Newton MessagePad communications devices to gain access to network services.

The LocalTalk Bridge features dynamic, user-selectable access modes. When access is set to Private, the LocalTalk devices and services--such as LaserWriter printers and shared Macintosh volumes--are hidden from users on the Ethernet or Token Ring network, while LocalTalk-only devices retain full access to the services on both sides of the network. In contrast, when access is set to Public, all devices are visible from both sides of the network.

Known Incompatibilities and Limitations

NOTE: The LocalTalk bridge will not function if a router is detected on the LocalTalk network. The LocalTalk Bridge can only be used on a LocalTalk segment that does not already have an active AppleTalk Internet Router, LaserWriter Bridge, hardware based router, or another LocalTalk Bridge.

Switching Interfaces

When LocalTalk Bridge 2.1 is installed, switching AppleTalk from one port to another may cause a crash. The LocalTalk Bridge should be disabled before switching ports.

Availability of Bridged Devices in the Chooser

To ensure that bridged devices are seen or available in the Chooser it is important that the Bridging Device (the Macintosh running LocalTalk Bridge) is booted and that the LocalTalk Bridge is loaded prior to booting the other machines in the LocalTalk network.

Device Bridging Limitations and Workstation Performance

There is no hard limit imposed by the code on the number of devices that can be attached to the LocalTalk segment. However, the number of devices is limited by the LocalTalk network architecture. If the LocalTalk network is properly repeated or bridged, there could be as many as 254 devices attached to the LocalTalk side of the bridge.

"Inside AppleTalk, 2nd Edition" states: "The physical characteristics of the LocalTalk twisted-pair cable allow it to reliably support a recommended maximum of 32 devices." So, without a bridge or repeater, the maximum limit is 32 devices.

However, 20 is the recommended number of devices recommended when the bridge is also being used as a workstation. For more devices than that the Macintosh should run as a stand-alone bridge, because there will not be enough computing cycles available to process the user's requests in a prompt manner. However, the degree of user requested responsiveness and ability of the machine to function as a bridge is a function of the speed of the underlying hardware and volume of bridged network traffic. Presumably faster machines under lighter network loads could remain more responsive to user requests while bridging up to the 32-device limit. High volumes of network traffic can significantly degrade the responsiveness of the bridging machine on even the fastest Macintoshes.

Mac OS 8.5 and Mac OS 8.5.1 Compatibility

The Open Transport 2.0 Read Me - Part 1 states the following:

  • Apple LocalTalk Bridge 2.1 is compatible with Open Transport.

However, Apple has done only limited testing with Apple LocalTalk Bridge under Mac OS 8.5. LocalTalk Bridge 2.1 is not believed to be completely compatible with Mac OS 8.5 though no specific incompatibility information is available.

Network Assistant performance over LocalTalk bridges

The Apple LocalTalk Bridge can affect the performance of Network Assistant. Performance degrades when transferring data or sharing screens between workstations on a LocalTalk network and an Ethernet network.

 To improve performance, set up screen sharing and file copying to the LocalTalk bridge workstation (and any workstations connected via that bridge) separately from the rest of the workstations and use a computer connected to an Ethernet network to administer the LocalTalk computers, not vice versa.

Token Ring Zones Inaccessibility on the Bridge Computer

If you install the Apple Internet Router and the Apple LocalTalk Bridge on the same computer, and both are running simultaneously, the bridge computer won't have access to Token Ring zones. To remedy this problem, remove either the router or the Bridge.

AWS95 & A/UX Compatibility

The LocalTalk Bridge software is not compatible with A/UX; therefore this bridge software cannot be run on A/UX or AWS 95 systems. The Bridge software needs AppleTalk version 58.1.5 or higher to operate, while the AppleTalk implementation in A/UX is based on AppleTalk version 56.

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