lat_intro, lat - Local Area Transport (LAT) support
The LAT protocol supports communications between host computer
systems and terminal servers with terminals, PCs,
printers, modems and other devices over local area networks
LAT software has the features required for a host to function
as both a service node and a server node, so requests
for connections can be made by server users and connections
can be originated to other service nodes.
The software also permits host applications to initiate
connections to server ports, designated as application
ports, to access remote devices.
The Tru64 UNIX LAT implementation is a STREAMS-based LAT
Types of Services [Toc] [Back]
Tru64 UNIX supports the following types of LAT services:
Bound interactive services
A bound interactive service that has specific LAT
devices (ttys) bound to it. When connecting to
this type of service, you are always logged onto a
tty that was bound to this service by the latcp
command. Unbound interactive services
An unbound interactive service does not have specific
LAT devices bound to it. When you access an
unbound interactive service, the service uses any
available LAT devices (ttys) that have not been
bound to any other service.
This is the default type of service that is added
when LAT is started or when no ttys are bound to
the service. If there is only one unbound interactive
service on the system, you cannot delete it.
Dedicated or optional services
A dedicated or optional service is used with specialized
applications, written especially for LAT.
The LAT/Telnet gateway is an example of a specialized
The latcp(8) reference page provides information on the
latcp commands used to create the different types of services.
To set up LAT for use on your machine, install the LAT
subset, OSFLATxxx (where xxx is the Tru64 UNIX version
number), and perform the following tasks: Configure and
reboot the kernel Set up the system for LAT Customize LAT
on your system (optional)
To do these tasks, you must log in as superuser.
The following sections briefly explain these tasks. For
more information, refer to the Network Administration:
Connections and System Administration manuals.
Kernel Configuration [Toc] [Back]
To configure the kernel for LAT, the system configuration
file must contain the Data Link Bridge (DLPI Version 2.0
Service Class 1) option.
For more information see the Network Administration: Connections
System Setup [Toc] [Back]
You can set up LAT on your system automatically by using
the latsetup utility, or manually. You should use the latsetup
utility to set up your system automatically.
When you set up your system automatically, the latsetup
utility performs the following functions: Creates the LAT
device special files Adds or removes getty entries to or
from the /etc/inittab file for incoming connections Executes
the init q command Starts or stops LAT services
Enables or disables LAT automatic startup and shutdown
For more information, see latsetup(8).
If you want to set up LAT manually, refer to lat_manual_setup(7).
LAT is not supported over NetRAIN virtual interfaces or
the adapters that compose NetRAIN sets. The latsetup
utility does not allow you to configure LAT over these
interfaces, and you should not attempt to do so manually.
User Customization [Toc] [Back]
You can use the latcp command to customize LAT on your
When LAT automatic startup and shutdown is enabled, the
/sbin/init.d/lat script is executed upon reaching run
level 3. When this script is executed, it reads the
/etc/latstartup.conf file (if this file exists) and executes
the latcp commands in the file. If the following
LAT parameters have not been set, the /sbin/init.d/lat
script starts LAT with the default values: Node name --
The default value is the host name. Multicast timer --
The default value is 60 seconds. Network adapter -- The
default is all network adapters connected to broadcast
media. Service name -- The default value is taken from
the LAT node name parameter.
The following parameters are set to the defaults
for each service, unless specified: Service
description -- The default value is ``HP Tru64 UNIX
Version X.X LAT SERVICE.'' Rating -- The default is
dynamic rating. Group code -- The default value is
0. Agent status -- The default is disabled. Outgoing
port groups -- The default is group 0. Maximum
number of learned services -- The default value
You can automate your LAT customization by creating a file
called /etc/latstartup.conf and entering your LAT customization
commands in this file. For example, you can
define a particular node name or add service names.
For more information on how to customize your system using
a /etc/latstartup.conf file, refer to the Network Administration:
Connections manual and latcp(8).
If your system is configured with multiple network
adapters, you can specify that the LAT protocol run over
the multiple adapters, provided they are connected to different
logical networks. If you have more than one network
adapter connected to a logical network, you should use
latcp to specify that the LAT protocol runs over only one
adapter. Running LAT over more than one network adapter
can cause unpredictable results. You can determine the
adapters defined on your system by using the netstat -i
CHANGING LINE DISCIPLINES [Toc] [Back]
The Tru64 UNIX LAT implementation is a STREAMS-based tty
design. In prior versions of Tru64 UNIX, the LAT implementation
was a clist-based tty design. Therefore, the
method for changing the LAT tty line discipline of a
STREAMS-based LAT tty differs from that of a clist-based
Your Tru64 UNIX LAT system is configured (through the
/etc/latautopush.conf file) to automatically push the
ldterm (POSIX line discipline) module upon opening a LAT
terminal device (tty). When the open call completes successfully,
the ldterm module is in place on the stream
above the LAT driver.
The Network Administration: Connections manual provides a
sample program that demonstrates how terminal (tty) line
disciplines are changed in a clist-based tty and a STREAMS
tty environment. Additionally, you can use the strchg
command to change the STREAMS configuration of the user's
For more information, see the autopush(8) and strchg(1)
Specifies the SVR4 LAT device special files. (Where n is
a number starting at 620 and having no upper limit.)
Specifies the BSD LAT terminal devices. (Where W is a number
from 0 to 9 and X is an alphanumeric character from 0
to 9, a lowercase a to z, or an uppercase character A to
Z.) LAT supports up to 620 BSD LAT terminal devices.
Specifies the LAT control device. Specifies the LAT
startup and shutdown script. Specifies LAT customization
commands. If your system is a member of a cluster, you
must create this file as a Context-Dependent Symbolic Link
(CDSL). See the System Administration guide for more
information. Sets up the system database to automatically
push the ldterm STREAMS module on top of the LAT STREAMS
driver, each time a LAT tty is opened. Controls the initialization
process. Specifies the system configuration
Commands: llogin(1), netstat(1), strchg(1), autopush(8),
init(8), latcp(8), latsetup(8), MAKEDEV(8), rcmgr(8),
Network Administration: Connections, System Administration
[ Back ]