This chapter provides introductory information on using 4DLT in a LAT session and instructions for starting and stopping SLAT, the 4DLT utility that supports your LAT connections. It also contains general instructions for entering SLAT commands and a SLAT command summary. This chapter contains these sections:
The 4DLT application must be installed in your workstation before you can start working. To use printer services, IRIX line printer software (eoe2.sw.lp) must also be installed. If 4DLT or lp software is not installed, you or your system administrator must complete the installation instructions given in the 4DLT Release Notes and the 4DLT Administrator's Guide. The 4DLT Administrator's Guide also contains instructions for setting up your login account so that 4DLT commands will execute from any directory in your account.
The period of time during which you have a connection to a LAT service is known as a session. You can establish several sessions from your terminal and switch between sessions, but you can work in only one session at a time. If the service node you are using fails during your session, the terminal server will attempt to establish another session with a duplicate service on another service node.
SLAT supports your connections to the LAT network. While you are working with SLAT, your IRIS workstation functions as a terminal server, forwarding your requests to network service nodes. The IRIS can be simultaneously functioning as a LAT service node, but this function will not be noticeable to you.
To use the SLAT utility, 4DLT software must be installed and running on your Silicon Graphics workstation. If it is not, you or your system administrator must complete the installation and startup procedures before you go further (see the 4DLT Administrator's Guide for instructions).
To start SLAT, enter the SLAT command at the IRIX prompt. This means that an open IRIX shell must be displayed on your screen. This example illustrates the SLAT command and the prompt that appears after your entry:
% slat <Enter> local> |
When you no longer need to use LAT network resources, you can stop the SLAT utility by using either the EXIT or QUIT command. EXIT and QUIT perform the same function. These examples illustrate the EXIT and QUIT commands and their abbreviations:
local> Exit <Enter> local> Quit <Enter> local> E <Enter> local> Q <Enter> |
After you stop SLAT, you automatically return to the IRIX system prompt.
SLAT commands are similar to the commands used with conventional terminal servers. They include commands such as CONNECT and DISCONNECT to open and close connections, SHOW SERVICES and SHOW NODES to list available resources, and the break sequence and RESUME command to move between active sessions.
SLAT accepts abbreviated forms of any of its commands. Any combination of letters that uniquely identifies the command is a valid abbreviation. For example, SHOW N is a valid command entry for SHOW NODES, but SHOW is not valid. (Chapter 3, “Using SLAT Commands,” contains numerous suggestions for abbreviating commands.)
SLAT provides a number of commands that you can use to display data about the LAT network during a session.The data originate at service nodes, which broadcast information about their services to the network every 60 seconds. Terminal servers collect this information in their databases and display it to users when they enter a SHOW SERVICES command.
Some data that you can display with SLAT commands is not relevant to end-users. For example, you can display the Ethernet number of a service node, but this information is intended primarily for network administrators and users rarely need it; however, LAT users frequently display service names, session numbers, and service ratings, and this data is important to using the network effectively.
Each service available on a LAT network is assigned a service name that identifies it to users and LAT software. Service names are listed when you enter a SHOW SERVICES command.
In some cases, a single service name represents a service offered by several service nodes. For example, assume a LAT network provides a graphics application with the service name rainbows. To avoid overburdening a single service node with all user requests for rainbows, the network manager can configure rainbows on several service nodes. Whenever a user selects the rainbows service, one node is chosen to provide it (see “LAT Service Ratings”).
When you have multiple LAT sessions running concurrently, it is important that you be able to distinguish among them. To make this possible, your terminal server assigns each of your sessions a session number. You display session numbers with the SHOW SESSIONS command.
Session numbers are assigned in the chronological order in which they are established: the first LAT session you establish is session 1, the next session you establish is session 2, and so on. Sessions maintain their assigned numbers until you disconnect from them.
The information that a service node broadcasts to the LAT network includes its node name, the name of the services it provides, and information describing each service. The descriptive information includes a service rating, a measure of the availability of the node for providing services. Ratings range from zero (0) to 255; the higher the rating, the more efficient the service the node is likely to provide.
When a terminal server receives a user request for a service, it checks its database for information about the service. If the service is offered on multiple nodes, the terminal server selects the node with the highest service rating.
By default, all terminal server users have access to every service on a LAT network, but a network administrator might assign group codes to manage access to services. If your network administrator chooses to assign group codes on your network, some resources on the LAT network might not be available to you. Resources that are not available to you will not be included in your SHOW SERVICES listings.
LAT network resources frequently include printers, and these devices can be included in the list of LAT services that you can display (see “The SHOW SERVICES Command” in Chapter 3). However, unlike LAT services such as user logins and applications, you do not connect to printers by means of the LAT CONNECT command.
To print to a LAT printer, you use the same command as you use for any non-LAT network printer that is accessible from your workstation. For IRIX users, this command is usually lp(1).
Table 2-1 gives an alphabetical listing of the commands available to 4DLT users. This table summarizes command functions and tells where you can find detailed information about using each command.
Table 2-1. 4DLT Command Summary
Command | Purpose | Detailed Description |
|---|---|---|
BACKWARD | When multiple LAT sessions are active, reactivates the session whose number is one less than the previously active session. | |
BREAK | Allows you to redefine the break key sequence. | |
break (key sequence) | Leaves a LAT session without breaking the session connection. | |
CONNECT | Establishes a connection to a LAT service. | |
DISCONNECT | Terminates a connection to a LAT service. | |
EXIT | Exits the LAT terminal server emulation. | |
FORWARD | When multiple LAT sessions are active, reactivates the session whose number is one more than the previously active session. | |
HELP | Displays a complete list of SLAT commands. | |
RESUME | Returns to a temporarily suspended session. | |
SHOW NODES | Post a list of LAT nodes and their status. | |
SHOW SERVER | Posts information about the node where SLAT is running. | |
SHOW SERVICES | Posts a list of LAT network services. | |
SHOW SESSIONS | Posts a list of established sessions. | |
SLAT | Starts the LAT terminal server emulation. |