lta(4) Kernel Interfaces Manual lta(4)
lta - lta pseudoterminal interface
The pseudoterminal interface provides support for local area transport (LAT) service. LAT service allows users to access remote nodes
through the Ethernet.
To configure the LAT service for your machine, you must:
o Edit the system configuration file.
o Edit the file.
o Create LAT special files.
o Edit the file.
Instructions for performing these tasks are further documented in the Guide to Ethernet Communications Servers.
Edit the Configuration File
Edit the configuration file to include the option and the and pseudo-devices. The configuration file to edit is located in
/sys/conf/vax/HOSTNAME or /sys/conf/mips/HOSTNAME (depending on your processor), where HOSTNAME is the name of your host processor, in
The optional value for the pseudo-device entry defines the number of LAT lines to configure, a number between 1 and 256. If you do not
specify a value, the default is 16 lines. For example, if you want to configure 32 LAT devices into your system, the entry for the LAT
To use the system as a load host for remote note maintenance functions such as loading and controlling terminal servers, you must also
include an options entry for and a pseudo-device entry for in the configuration file.
Edit the /etc/rc.local File
Edit the file to restart LAT service automatically when the system reboots. Add the following entry after the commands for local daemon
if [ -f /etc/lcp ]; then
/etc/lcp -s > /dev/console & echo -n ' lat' >/dev/console
Create LAT Special Files
Create the LAT special files by running the program from the directory and specifying the option. You create one LAT special file for each
LAT device. For example, the following commands create 32 device special files for LAT devices:
# cd /dev
# MAKEDEV lta0
# MAKEDEV lta1
The option range is 1 to 7. The maximum number of LAT special files is 256.
Edit the /etc/ttys File
Edit the file to include entries for all the LAT special files you created using the command. For more information on how to add these
Contains terminal devices defined to the machine.
Contains terminal devices defined to the machine (modem lines only).
Guide to Ethernet Communications Servers
Check Out this Related Man Page
lcp(8) System Manager's Manual lcp(8)
lcp - Local Area Transport server (LAT) control program
/etc/lcp [ options ]
The LAT control program, provides the essential functions to control and manage LAT terminal service. It allows you to start and stop LAT
service, modify and display configuration characteristics, and display and set error counters to zero. The following command is usually
included in the file to automatically restart LAT service during reboot:
The following options can be set with
-s Starts LAT service. Enables connections from LAT terminal servers to host. If LAT parameters have not been set, they take on
default values specified in the option.
-r Resets LAT parameters to the following default values:
multicast timer: 30 seconds
node description: ``ULTRIX''
service description: ``ULTRIX LAT SERVICE''
-g Sets groups to grp1, grp2, ... , grpn. A number or string of numbers can be used to set groups. The numbers used for each
group must be less than or equal to 255. For example:
lcp -g 128
lcp -g 56,5,102,10,20,30,40,50,60,...,
A string of groups must be separated by commas with no spaces. If the string exceeds the width of the screen it must wrap
over to the following line. You cannot use a backslash () or a carriage return to break a string.
-h Sets a list of ttys (next argument) as being available only for host-initiated connections. A string of ttys must be sepa-
rated by commas with no spaces. If the string exceeds the width of the screen, it must wrap over to the following line.
You cannot use a backslash () or a carriage return to break a string. Each tty can optionally be associated with a spe-
cific port on a specific terminal server by following the tty name by the name of the server and port, separated by colons.
For example, the following command associates tty15 with the port named "PORT7" on the terminal server named "LAT_SERVER".
/etc/lcp -h /dev/tty15:LAT_SERVER:PORT7
-H Sets a list of ttys (next argument) as being available only for terminal server initiated connections. A string of ttys
must be separated by commas with no spaces. If the string exceeds the width of the screen it must wrap over to the follow-
ing line. You cannot use a backslash () or a carriage return to break a string.
-m Sets multicast transmission timer to the specified time (next argument). A node advertises its presence to the LAT servers
by sending out a multicast message over the network. The time variable sets the interval between transmissions. Valid inter-
vals range from 10 to 255 seconds, with a default of 30 seconds.
-n Sets node to the specified name (next argument). Specifies the name that your node will be known by. Although the Terminal
Server keeps track of nodes without an associated nodename, a LAT node must have a nodename in order for a terminal user to
establish a connection. A node can have a list of associated services and service ratings, specified by up to 16 alphanu-
meric characters. Dollar ($) and underscore (_) characters are valid, but leading underscores and trailing colons are
removed. The nodename must be unique on the Ethernet. The Terminal Server displays the nodename as a service if you type the
command, and as a node if you type the command. The nodename default is the hostname.
-N Sets node description to the specified message (next argument). The node description allows for a short message to be dis-
played to LAT users, providing news or additional node information. Specify up to 64 alphanumeric characters. Dollar ($)
and underscore (_) characters are valid, but leading underscores and trailing colons are removed. Leading ampersands (&)
are not allowed. The default is ``ULTRIX''. You must enclose the string in double quotation marks (" ") if it contains one
or more spaces.
-v A service node advertises one or more services. By default the single service offered is the node name. For example, node
by default offers service The option lets you change this default. It also lets you cause the service node to advertise
more than one service and associate a given set of LAT ttys with each service by appending a list of minor device numbers to
the service name. For example, the following command causes the node to offer two additional services, "SERV1" and "SERV2":
/etc/lcp -v microv -v SERV1:/dev/tty15,/dev/tty16
Devices tty15 and tty16 are used for SERV1. Devices tty17, tty18, and tty19 are used for SERV2. All other LAT ttys are
used for the default service,
Note that normal LAT service is always associated with the first option to appear. Therefore, if you wish to advertise additional services
you must define the service name for normal lat, even if you still want the default service name, as in the above example.
Every time you issue a new lcp command with the option, the new set of services that you define completely replaces any previously defined
services. To discontinue a previously defined service, reissue lcp with the option without specifying that service. For example, to dis-
continue the SERV1 service, use the following command:
/etc/lcp -v microv
-V Sets service description to specified message (next argument). It can be up to 64 characters in length. You must enclose
the string in double quotation marks (" ") if it contains one or more spaces. If you are defining multiple services a given
description applies to the service name defined by the corresponding option (the first option corresponds to the first
option, and so on). For example, the following command associates the description "ULTRIX LAT service" with the service name
and description "service 1" with service name "SERV1".
/etc/lcp -v microv -v SERV1:dev/tty15,dev/tty16
-V "ULTRIX LAT service" -V "service 1"
-t Stops LAT service. Disable connections from LAT terminal servers to host.
-d Displays LAT characteristics. Shows the LAT parameters at their current setting. The following is an example of the output
of the option:
% /etc/lcp -d
Node name: NODE Service name: NODE
Node Identification: ULTRIX LAT service
Service Identification: ULTRIX
Multicast timer: 30 seconds
LAT version: 5 eco: 0 LAT Protocol is active
-z Reinitializes (zeroes out) error counters. To test system performance over a period of time, zero the counters and observe
the information that accumulates.
-c Displays error counters in vertical format. If an interval also is specified (next argument), displays error counters in
horizontal format every interval seconds. The following is an example of the output of the option:
% /etc/lcp -c
67413 Frames received (rcv)
32 Duplicate frames received (rcvdup)
89005 Frames transmitted (xmit)
62 Retransmissions (rexmit)
0 Illegal messages received (illmesg)
0 Illegal slots received (illslots)
interval Continuously displays error counters in horizontal format, waiting interval seconds between each iteration. Quit by sending
a keyboard interrupt. The following is an example of the output of the interval option:
% /etc/lcp 10
rcv rcvdup xmit rexmit illmesg illslots
67474 32 89066 62 0 0
67483 32 89067 62 0 0
67491 32 89073 62 0 0
67502 32 89089 62 0 0
-p Shows which LAT server/port combination a specific LAT tty device is connected to. For example the following command dis-
plays which terminal server and port are associated with tty15.
/etc/lcp -p /dev/tty15
The service and node names cannot be more than 16 characters long.
The user must have read and write access to a terminal.
The meaning of each error counter is explained below.
rcv Number of Ethernet LAT messages
rcvdup Number of duplicate messages received (normally indicates a system slowdown)
xmit Number of transmitted Ethernet LAT messages
rexmit Number of transmit frames that are sent more than once
illmesg Number of bad messages flagged by the LAT driver
illslots Number of bad transmission slots flagged by the driver
Messages indicating that user is not privileged or that LAT service is not loaded