LAT Protocol Doesn‘t Pass Through A Router (5/94)

We are having problems using the DEC LAT protocol on our LAN. We use LAT because the database we use is on a VAX that requires it.

We have about 300 Macintosh computers on Ethernet and 100 on LocalTalk. We are using a DEC DEMPR as a hub for all the Ethernet computers and an Internet Router to go to LocalTalk. We have 18 10BaseT hubs that run back to the DEMPR. On the other side of the DEMPR we have thin Ethernet that is serving as the backbone for a small cluster of VAX computers.

We are using some of the Macintosh computers as VAX terminals through Ethernet utilizing the LAT tool. Because of the inability of the LAT tool to "pass through" routers, we have designed this entire network as one big Ethernet segment.

1) Is there any way to encapsulate LAT into either AppleTalk or IP in the cisco Router so we can segment the network?

2) Can we use PATHWORKS and ADSP on the VAX as a terminal server getting around the LAT and router limitation, and use AppleTalk all the way to the VAX?

3) What might be a better solution to this problem? (That is software or hardware which might work better.)

According to Digital documentation on PATHWORKS (Client Admin Guide page 2-1) LAT architecture does not work over routers. DEC offers no technical explanation.

DEC has provided a work around for this problem. It's called The AppleTalk LAT Gateway. The following are instructions for installing and connecting to the Gateway. This solution is found starting on Chapter two, page one of PATHWORKS Client Admin Guide.

The requirements are: A Macintosh connected to Ethernet. This "should" be a stand alone server computer. If the Macintosh is connected to LocalTalk it won't work.

To configure the LAT Gateway Server you should:

1) Drag the "AppleTalk LAT - Gateway" software to the server Macintosh.
2) Launch the AppleTalk LAT - Gateway application.
3) Provide a name for the server.
4) Click the configuration boxes as required by the installation.

To connect to the Gateway you should:

1) Launch the application (I will use MacTerminal for an example).
2) Pull down the settings menu and select connections.
3) Select "AppleTalk - LAT" and the connection method.
4) Choose gateway and then the correct zone and gateway name.
5) Click OK. Wait a few seconds for the Gateway Service to identify
itself.
6) Then select the "service" option and the desired gateway.
7) Click OK.
8) Close the dialog box and select "open connection" under the session
menu.

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Published Date: Feb 19, 2012