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HP OpenVMS System Management Utilities Reference Manual

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The default device seed value is approximately half of the maximum unit number (which you set by using the /UNIT_NUMBER_MAXIMUM qualifier). Interactive LAT ports, and those created with the CREATE PORT/LOGICAL command, are assigned unit numbers beginning with the specified device seed value and continuing up to the maximum unit number. When the maximum unit number is reached, the port is assigned the next available unit number beginning at the bottom of the range (LTA1:).

Note that each time you specify the /UNIT_NUMBER_MAXIMUM qualifier, the device seed value is reset to approximately half of the newly specified maximum unit number.

/FORWARD_SESSION_LIMIT[=value]

Controls the number of sessions (a value within a range from 16 to 255) allowed on each outgoing connection. By default, 16 sessions are allowed on an outgoing connection, which means that 16 individual processes can direct the DCL command SET HOST/LAT to the same remote node.

You must increase the value for the /FORWARD_SESSION_LIMIT qualifier if a user on your system enters the command SET HOST/LAT and receives an error message indicating that the session limit for the LAT circuit has been reached (%LAT-F-VCSESLIM). Note, however, that you can change this value only when no connections exist.

/GROUPS=option[,...]

Gives the listed groups access to services offered on your local node or prevents the listed groups from accessing services offered on your local node, depending on the options used.

A network manager organizes terminal server nodes into groups based on the number of terminal server nodes in the LAT network. Groups subdivide the LAT network, limiting the number of terminal server nodes that can connect with a given service node.

As many as 256 groups, numbered 0 to 255, can be in the LAT network. By default, all terminal server nodes and nodes supporting outgoing connections belong to group 0. If you enter one group code, you can omit the parentheses. Use the SHOW NODE command for a list of the groups enabled for your service node.

The /GROUPS qualifier has several options. For each option described, you can specify more than one group by:

  • Listing them separated by commas
  • Specifying a range

The available options are:

ENABLE= group-code[,...] Gives the listed groups access to your service node.
DISABLE= group-code[,...] Prevents the listed groups from accessing your service node. The listed groups had been enabled previously for access to your node.
ENABLE= group-code[,...],
DISABLE= group-code[,...] 		This option lets you enable certain groups and disable other groups in one command line: gives access to the groups listed with the ENABLE option and removes access from the groups listed with the DISABLE option. Enclose both ENABLE and DISABLE in parentheses; for example, /GROUP=(ENABLE=(10,12),
DISABLE=(1-30)).

Example 2 shows how to specify the /GROUPS qualifier with the SET NODE command.

/IDENTIFICATION[="identification-string"]

Describes and identifies a node. Service nodes include the identification string in service announcements. A service node announces its services at regular intervals established with the SET NODE command. Entering the LATCP command SHOW NODE or the DECserver command SHOW NODE generates a display that includes this identification string. By default, the identification string is the translation of SYS$ANNOUNCE.

You cannot specify more than 64 ASCII characters in an identification string (a SYS$ANNOUNCE longer than that will be truncated to the first 64 characters). Enclose the string in quotation marks (" ").

/KEEPALIVE_TIMER[=secs]

Controls the maximum interval, in seconds, between idle run messages sent by your local node to another service node to which it has a LAT connection. Your node sends these messages when no other traffic is being generated over the virtual circuit. If the service node acknowledges these messages, your node will continue to monitor the status of the circuit. If your node does not receive acknowledgment, it responds as if the circuit is down.

Use this qualifier only if your node allows outgoing connections (/CONNECTIONS=OUTGOING_ONLY or /CONNECTIONS=BOTH).

The default value is 20. HP recommends this value for normal LAN environments. For a heavily loaded LAN, consider using a higher value. Set the timer in the range of 10 to 255. For applications that require quick notification and possible failover of a service node failure, use a lower value. You cannot change this value if active or pending connections exist.

/LARGE_BUFFER

/NOLARGE_BUFFER

Controls whether the LAT software uses large buffers while managing communications between OpenVMS systems (the default).

If you must use the /NOLARGE_BUFFER qualifier (for example, to limit packet sizes to be no larger than the Ethernet maximum), HP recommends that you specify this command after all logical LAT links have been created and before the LAT node has been turned on. For example, note the following commands in LAT$SYSTARTUP.COM: 


 $!
 $! Create each logical LAT link with a unique name and
 $! unique LAN address (forced with /NODECNET).
 $!
 $ LCP CREATE LINK FDDI_1 /DEVICE=FCA0 /NODECNET
 $ LCP CREATE LINK FDDI_2 /DEVICE=FCB0 /NODECNET
 $!
 $! Don't use large buffer support (force packet
 $! sizes to be no larger than what Ethernet can
 $! support).
 $!
 $ LCP SET NODE /NOLARGE_BUFFER
 $!
 $! Turn on the LAT protocol.
 $!
 $ LCP SET NODE /STATE=ON

/LOG

/NOLOG (default)

Specifies whether LATCP displays a message confirming that the node's characteristics were modified. If you do not specify the /LOG or /NOLOG qualifier, the default is that no message will be displayed.

/MULTICAST_TIMER[=secs]

Specifies the time, in seconds, between multicast messages sent by a service node. A multicast message announces the services offered by a service node. The minimum value is 10 seconds; the maximum is 180 seconds. The default value is 60.

/NODE_LIMIT=value

/NONODE_LIMIT

Specifies the maximum number of service nodes that your local node can store in its service and node database. Use this qualifier only if your node allows outgoing connections (/CONNECTIONS=OUTGOING_ONLY or /CONNECTIONS=BOTH).

When the database reaches the node limit, no more nodes are added to the database when your local node receives service announcement messages. You can ensure that the node limit is not reached by using the /USER_GROUPS qualifier to restrict access from the local node to other service nodes on the network.

If you do not specify either the /NODE_LIMIT=value or /NONODE_LIMIT qualifier, the default is no limit. A value of 0 indicates no limit.

/QUEUE_LIMIT=value

Sets a limit on the number of entries (incoming LAT connections only, not outgoing printer connections) that are queued on the system. The queue limit value can range from 0 to 200, with a default of 24. A value of 0 indicates that no queuing is allowed.

/RETRANSMIT_LIMIT[=count]

Specifies the number of times your local node repeats transmission of a message to a service node after a transmission fails. If the transmission is still unsuccessful after these attempts, the virtual circuit between your local node and the service node terminates, along with all sessions associated with the virtual circuit.

Use this qualifier only if your node allows outgoing connections (/CONNECTIONS=OUTGOING_ONLY or /CONNECTIONS=BOTH).

Specify a value in the range of 4 to 120. The default is 8. The value you choose depends on the type of physical link used for your network, as well as the amount of traffic on the network. See your network manager for a suggested value. You cannot change this value if active or pending connections exist.

/SERVICE_RESPONDER

/NOSERVICE_RESPONDER

Specifies whether your system responds to special LAT multicast messages that request service information. Some terminal servers do not have their own service and node database. When a user on such a terminal server requests a connection to a service, the server sends a LAT multicast message requesting names of nodes that offer the requested service. Service responder nodes reply with the requested information.

If you specify /SERVICE_RESPONDER, your system responds to the special LAT multicast messages. (If you specify /NOSERVICE_RESPONDER, your system does not respond to those messages.) HP recommends that you set up only one or two nodes in the LAN as service responder nodes. The nodes should have the largest databases in the LAN. Use this option only if your node allows outgoing connections (/CONNECTIONS=OUTGOING_ONLY or /CONNECTIONS=BOTH).

If you do not specify either the /SERVICE_RESPONDER or /NOSERVICE_RESPONDER qualifier, the default is that your system will not respond to the special LAT multicast messages.

/SESSION_LIMIT=option

Specifies the maximum number of simultaneous sessions across all local-access ports. This limit does not affect the use of dedicated and application ports. It affects interactive port creation only, limiting the amount of resources consumed by interactive users creating new sessions.

The options for the /SESSION_LIMIT qualifier are:

INCOMING= value Sets the session limit for incoming connections only. The default is no limit (a value of 0).
OUTGOING= value Sets the session limit for outgoing connections only. The default is no limit (a value of 0).
INCOMING= value,OUTGOING= value Sets the limit for both outgoing and incoming connections. Enclose both options in parentheses; for example, /SESSION_LIMIT=(INCOMING=20, OUTGOING=25).
  • A high limit allows users to have more sessions but increases memory utilization on your local node.
  • A low limit decreases memory utilization on your local node but limits user access to services on the network.

If the limit is reached, interactive users cannot create new sessions. In this case, increase the session limit or disconnect any connections that are no longer being used.

Specify a value in the range of 0 to 255. Specifying 0 leaves no limit on the number of sessions that can be created. To prevent sessions from being created, use the /CONNECTIONS qualifier.

Not specify the /SESSION_LIMIT qualifier causes no limit on the number of incoming and outgoing sessions. This is the default.

/STATE=option

Specifies whether LAT connections are allowed. The three options for STATE are:
ON Starts the LAT port driver (and LAT protocol software) on your node.

HP strongly recommends that the LATCP command SET NODE/STATE=ON be executed before any LTA application or dedicated ports are created (use the format provided in SYS$MANAGER:LAT$SYSTARTUP.TEMPLATE) for two reasons:

  • It ensures that LTDRIVER will delete any leftover LTA devices that have a reference count of 0 and are explicitly marked for deletion (using the $DASSGN system service or the LATCP command DELETE PORT, for example). Because every LATCP management port (LATCP$MGMT_PORT) that was created by the previous LATCP invocation is deleted, no conflicts result with the LAT application ports or newly created dedicated ports.
  • The deletion of leftover LTA devices with a reference count of 0 minimizes the use of nonpaged pool memory.
OFF Stops the LAT port driver (and LAT protocol software) on your node. Any existing LAT connections are aborted. Any characteristics that you changed or set with LATCP are lost.

To start the LAT protocol on your node again, invoke LAT$STARTUP.COM. (Refer to the HP OpenVMS System Manager's Manual for more information.) The LAT characteristics defined in LAT$SYSTARTUP.COM will take effect.

SHUT Specifies that new LAT connections cannot be created on your local node, but existing connections may continue. The LAT protocol continues running only until the last active session disconnects, (after which LTDRIVER will stop). At that time, your node changes to the OFF state.

Caution
If you stop the LAT software by specifying either the SET NODE/STATE=OFF or SET NODE/STATE=SHUT command, the LAT print symbiont (LATSYM) will shut down all print queues that it is processing. The system will then generate an OPCOM message indicating that the print queues are stopped. You must manually restart those print queues.

If you do not specify the /STATE=option qualifier, the default is that the LAT port driver and LAT protocol software on your node will be started (ON).

/UNIT_NUMBER_MAXIMUM=value

Specifies the maximum unit number for a LAT device. For example, if you specify 140, then LTA140: will be the device with the highest unit number. Specify a value that is high enough to accommodate all devices that may be in use simultaneously. When the number of devices in use exceeds the value you specify, the system gives certain LAT devices unit numbers that exceed your maximum.

Also note the following points:

  • When LATCP reaches the maximum unit number, it will continue to implicitly create LTA devices beginning with the lowest available unit number.
  • You cannot use the System Generation utility (SYSGEN) to set the maximum unit number for a LAT device.

The range of maximum unit numbers is 99 to 9999. The default is 9999. Note that each time you specify the /UNIT_NUMBER_MAXIMUM qualifier, the LTA device seed value is reset to approximately half of the newly specified maximum unit number.

/USER_GROUPS=option[,...]

Restricts access (from the local node) to service nodes in the network that belong to the specified groups. Your local node can access only those service nodes associated with the user groups specified. The /USER_GROUPS qualifier also serves to limit the number of nodes stored in your node's node database. (The local node only stores information about the nodes and services that belong to at least one of the specified user groups.) By default, all LAT service nodes belong to group 0.

This qualifier affects your local node when outgoing connections are enabled (/CONNECTIONS=OUTGOING_ONLY or /CONNECTIONS=BOTH).

Use the SHOW NODE command for a list of the user groups (service groups) enabled for your node.

The /USER_GROUPS qualifier has several options. For each option described here, you can use two ways to specify more than one group:

  • List them separated by commas.
  • Specify a range.

The available options are as follows:

ENABLE= group-code[,...] Gives your node access to the listed user groups.
DISABLE= group-code[,...] Prevents your node from accessing the listed groups. The listed groups were enabled previously.
ENABLE= group-code[,...],
DISABLE=group-code[,...] 		This option lets you enable certain groups and disable other groups in one command line: gives your node access to the groups listed with the ENABLE option and prevents your node from accessing the groups listed with the DISABLE option. Enclose both ENABLE and DISABLE in parentheses; for example, /GROUP=(ENABLE=(10,12),
DISABLE=(1-30)).

Description

The SET NODE command, which is typically executed in the site-specific LAT configuration command procedure, LAT$SYSTARTUP.COM, allows you to specify such characteristics as:
  • Node name
  • Node identification
  • Service and user groups
  • Timing of service announcements
  • The maximum number of LAT sessions allowed simultaneously on the node
  • The maximum number of outgoing sessions and incoming interactive sessions

Because LATCP commands change characteristics dynamically (that is, the commands take effect immediately), you can use the SET NODE command any time the LAT port driver is active. These changes remain in effect until the LAT port driver stops. To make sure the changes take effect when you start the LAT port driver again, edit LAT$SYSTARTUP.COM to include these changes. Start the LAT port driver by invoking LAT$SYSTARTUP.COM.

The HP OpenVMS System Manager's Manual contains additional information about the LAT network in general and service nodes in particular.

Note
The SET NODE command must be executed first (after LTDRIVER is loaded and the LATACP is started) to ensure that other management commands execute properly thereafter.

Examples

#1 

LATCP> SET NODE DUKE /IDENT="NODE DUKE, SALES VMSCLUSTER"

This command specifies node name DUKE for your local node. The identification string "NODE DUKE, SALES VMSCLUSTER" is multicast from node DUKE.

#2 

LATCP> SET NODE /MULTICAST_TIMER=50 /GROUPS=(ENABLE=(1-3,8,11),DISABLE=5)

This command causes your local node to send multicast messages every 50 seconds to announce DUKE's services to terminal servers. The command also enables groups 1, 2, 3, 8, and 11 for access to the local node, and it disables group 5 from accessing the local node. Group 5 had been previously enabled.

#3 

LATCP> SET NODE /CONNECTIONS=BOTH /USER_GROUPS=(ENABLE=(24,121-127),DISABLE=0)

This command sets up your local node to allow both incoming and outgoing connections. Users on your local node can access those service nodes belonging to user groups 24 and 121 through 127. Users cannot access service nodes in user group 0.

#4 

LATCP> SET NODE /CIRCUIT_TIMER=80 /KEEPALIVE_TIMER=20 -
_LATCP> /RETRANSMIT_LIMIT=20 /CONNECTIONS=BOTH /MULTICAST_TIMER=60-
_LATCP> /GROUPS=(DISABLE=0,ENABLE=73) /SESSION_LIMIT=(OUTGOING=10,INCOMING=0)

This command sets many characteristics at once for node DUKE.

SET PORT

Associates a logical port on the local node with a remote port on a terminal server that supports a device. Alternatively, it associates a logical port on the local node with a specific service. The service can be offered by a terminal server or associated with one or more dedicated ports on a remote LAT service node.

You must have OPER privilege to use this command.

Format

SET PORT port-name

Parameter

port-name

Specifies the name of the port. A port name must be in the form LTAn:, where n is a unique number from 1 to 9999.

Note
You cannot use the CREATE PORT and SET PORT commands, along with the DCL command SET TERMINAL, to change the characteristics of a DECserver port unless there is an existing LAT connection to that DECserver.

Qualifiers

/APPLICATION

Specifies that a port on the local node is an application port, logically associated with a port on a terminal server or a dedicated port on another LAT service node. The terminal server port supports a device (for example, a printer). If the port is used to support a printer, the print queue is established in a startup command procedure. Refer to the HP OpenVMS System Manager's Manual for a description of configuring remote printers on a terminal server.

If you do not specify a port type, the default port type is APPLICATION.

/DEDICATED

Specifies that a logical port on your local node is dedicated to an application service. The /DEDICATED qualifier requires the /SERVICE qualifier.

To set up an application service for a logical port on a LAT service node:

  1. Create the service by specifying the CREATE SERVICE/APPLICATION command and then define the dedicated port by specifying the CREATE PORT/DEDICATED command. You can include these commands in LAT$SYSTARTUP.COM.
  2. Associate the dedicated ports with the service by specifying the SET PORT/DEDICATED/SERVICE command.
  3. Start the application program. Within the program, allocate dedicated ports with the same name as those defined in LAT$SYSTARTUP.COM.

/LIMITED

Specifies that a logical port on your local node is limited to a service in the same way a port created using the /DEDICATED qualifier is dedicated to an application service. The difference is that ports created using the /LIMITED qualifier are under the control of the system login image (LOGINOUT.EXE) instead of an application program (a user who connects to a limited service and is assigned to a limited port receives the Username: prompt).

Using the /LIMITED qualifier, you can create a limited number of ports and map them to a specific service offered by the host system. If users are logged in to all of the limited ports for the service, no more connections are allowed to that service (terminal server users receive a "service in use" message).

/LOG

/NOLOG (default)

Specifies whether LATCP displays a message confirming that the port's characteristics were modified. If you do not specify the /LOG or /NOLOG qualifier, the default is that no message will be displayed.

/NODE=remote-node-name

Specifies the name of a terminal server (or a remote node that supports outgoing connections) to be logically associated with the specified application port on your node. The server supports a remote device. Note that you can set up an application port on your local node and associate the port with a dedicated port on a remote LAT service node. The remote port is dedicated to an application service.

/PASSWORD=remote-password

Specifies the password required to access a remote service that is logically associated with the specified application port.

/PORT=remote-port-name

Specifies the name of the remote port on a terminal server that supports a remote device, or specifies the name of a remote port dedicated to an application service on a remote LAT service node. In either case, the remote port is logically associated with the specified application port on your local node.

/QUEUED

/NOQUEUED

Specifies queued or nonqueued access to the server port. A queued or nonqueued request is accepted by a terminal server if a remote port is free. If the remote port is busy and queuing is enabled on the terminal server, then the server queues the remote request. If you do not want your remote requests to be queued on the server, specify /NOQUEUED.

Not specifying either the /QUEUED or /NOQUEUED qualifier results in queued access to the server port. This is the default.

/SERVICE=service-name

Specifies either of the following names:
  • The name of the remote service offered at a terminal server port that will be associated with the specified application port (/APPLICATION) on the local node
  • A service name for an application program being offered on a dedicated port (/DEDICATED) on a LAT service node

To specify the name of a remote service offered at a terminal server port, use the /NODE and /SERVICE qualifiers. To specify a particular port for a service, use the /NODE, /PORT, and /SERVICE qualifiers. Ask the terminal server manager for these names.

To name a service for a particular application program to be offered locally on a dedicated port, use the /DEDICATED and /SERVICE qualifiers. (The service must have been created with the CREATE SERVICE command.) Assign only one service to a dedicated port, but note that several ports can have the same service assigned.

Description

The SET PORT command associates an application port on your local node with a port or service on a terminal server.

To create a port, use one of the following methods:

  • Interactively enter the CREATE PORT command.
  • Run a program that creates ports.

When you associate an application port with a service on a terminal server, you allow access to any of the ports (printers) represented by that service (see Examples 1 and 2). Note that the application port must have been created with the CREATE PORT/APPLICATION command.

The SET PORT command can also associate a dedicated port on the local node with an application service offered locally. The service must already exist (see Example 3). Note that you must use the /DEDICATED and /SERVICE qualifiers.

The SET PORT command can also associate an application port on your local node with an application service associated with one or more dedicated ports on a remote LAT service node. This service is offered to users on terminal servers or on nodes that support outgoing connections (see Example 4). Note that the dedicated port must have been created with the CREATE PORT/DEDICATED command.

You can also set up the port as a limited port, using the /LIMITED qualifier.

Examples

See the examples for the SHOW PORT command for displays that reflect the changes made by the following SET PORT command examples.
#1 

LATCP> SET PORT LTA22: /APPLICATION /NODE=TS33EW /PORT=LN02

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