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 (LAN).
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
The software also permits host applications to initiate connections to
server ports, designated as application ports, to access remote
The Tru64 UNIX LAT implementation is a STREAMS-based LAT driver.
Types of Services
Tru64 UNIX supports the following types of LAT services: Bound interac‐
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 appli‐
cations, written especially for LAT. The LAT/Telnet gateway is
an example of a specialized application.
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 informa‐
tion, refer to the Network Administration: Connections and System
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 man‐
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 per‐
forms 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
You can use the latcp command to customize LAT on your system.
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 ser‐
vice, 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 is 100.
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
For more information on how to customize your system using a /etc/lat‐
startup.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. Run‐
ning 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 command.
CHANGING LINE DISCIPLINES
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 disci‐
pline of a STREAMS-based LAT tty differs from that of a clist-based LAT
Your Tru64 UNIX LAT system is configured (through the /etc/latauto‐
push.conf file) to automatically push the ldterm (POSIX line disci‐
pline) 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 pro‐
gram 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 standard input.
For more information, see the autopush(8) and strchg(1) reference
Specifies the SVR4 LAT device special files. (Where n is a number
starting at 620 and having no upper limit.) Specifies the BSD LAT ter‐
minal devices. (Where W is a number from 0 to 9 and X is an alphanu‐
meric character from 0 to 9, a lowercase a to z, or an uppercase char‐
acter A to Z.) LAT supports up to 620 BSD LAT terminal devices. Spec‐
ifies 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 file.
Commands: llogin(1), netstat(1), strchg(1), autopush(8), init(8),
latcp(8), latsetup(8), MAKEDEV(8), rcmgr(8), strsetup(8)
Network Administration: Connections, System Administration