Local Area Transport (LAT) is not part of the DNA specifications. It is a fast transport mechanism designed to allow dumb terminals and printers to communicate with a Digital host. It was designed to be used in conjuction with terminal servers which would multiplex async connections to the Host using a virtual circuit.

The LAT specs are *not* available on the web. They are released to licensed implementors only. Of course those people who have worked for Digital or have at some point had to support LAT, end up finding a paper copy.

I don't know of many other people with Lat pages, but Jan Bollen has some info up on his web page.

And Mike Sullenberger has a Lat Chalktalk on the web, which he has delivered in the past ( and probably would again, on request).

The Cisco Lat docs are at

Lat Configuration Commands.

The Cisco Protocol Translation docs are at

Protocol Translation and Virtual Asynch Commands.

I have put together several worked examples over the last year or two, and will include them here as I flesh out the pages. If I can find some natty pictures then I'll put together a full guide to LAT, but I'm notoriously haphazard with documentation.

A few notes on what has changed with LAT V5.3 , which we do NOT implement.

Simple use of Cisco Commserver to replace DECserver.

Quick explanation on Lat node names and service names.

Why Translations have to point to a service name and not a port name.

Simple Lat -> TCP translation for a Printer

Worked example of Lat to TCP Protocol Translation over an ISDN line.

This is an example of Lat -> TCP -> Lat translation over and ISDN link. Quite simple really, but the remote TCP -> Lat translation makes it a bit weird for people to understand first time around. What makes it harder is that I'm doing 3 things on two routers. So I'll get around to simplifying this. One Day !

Worked example of LAT group codes.

Explanation of LAT print queues Stalling during Protocol Translation.

Some sniffer decodes of Lat Packets. I'll add some more as I capture pretty ones.

Some Lat bugs

Bug Id	Version fixed	Subject
CSCdk57205	Resolved	sc=16 stalls VAX print queue in LAT/TCP translation
CSCdj09876	Resolved	Illegal slot values sent in Lat packets
CSCdj88645	Junked	LAT printing with V5.3
CSCdm45049	Resolved	LAT print jobs back to back fail
CSCdp28529	Resolved	Aborting LAT print jobs causes router to crash

If these are of any use to you, please let me know, and if there is something you would like me to explain here, then again, let me know and I'll try to write something useful

conrad@cisco.com