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HP OpenVMS System Management Utilities Reference
Manual
CREATE LINK
Creates the LAT data links, which are connections to LAN devices, such
as Ethernet or FDDI (Fiber Distributed Data Interface) controllers,
that you want your node to use. You must have OPER privilege to use
this command.
Format
CREATE LINK link-name
Parameter
link-name
Specifies a name for a LAT data link. A link name can have up to 16
ASCII characters. The characters allowed are as follows:
- Alphanumeric characters: A--Z, a--z, 0--9
- A subset of the international character set: ASCII codes 192--253
- Punctuation characters: dollar sign ($), hyphen (-), period (.),
and underscore (_)
You can create a maximum of eight links on your local node. Use the
SHOW LINK command for a list of the link names that are defined for
your node.
Qualifiers
/DECNET (default)
/NODECNET
Directs LAT protocol to use the DECnet data link address (/DECNET) or
the hardware address (/NODECNET) when starting the LAN controller. If
you do not specify the /DECNET or /NODECNET qualifier, the default is
that the LAT protocol will use the DECnet data link address.
Note that if you enter the CREATE LINK command with the /DECNET
qualifier and receive an error message indicating a "bad parameter
value," it means the SCSSYSTEMID system parameter is set to an
illegal value. To change the value of this parameter, use the following
formula:
In the formula, a is the DECnet area and n is the
DECnet computer number. If the value is outside the range of 1025 to
65535, the LAT protocol cannot start.
When you use the /NODECNET qualifier, the LAN device driver code
determines which address to use. For example:
- If SCSSYSTEMID is set to 0 but DECnet is already running on an
Ethernet controller, the LAN device code allows LAT to use the same
address as DECnet (AA-00-04-00-xx-xx).
- If SCSSYSTEMID is set to 0 and DECnet is not running, the
08-00-2B-xx-xx-xx address is used (a different address format is used
if your LAN controller is supplied by a vendor other than HP).
- If the setting for SCSSYSTEMID is the same as the DECnet node
number and DECnet is not running, the LAN device code forces LAT to use
the AA-00-04-00-xx-xx address.
If DECnet is configured on the system (or if the system is part of a
cluster), SCSSYSTEMID may contain a nonzero value. This is a problem
only when the system has 2 or more LAN controllers connected to the
same logical LAN.
For example, if your system has an FDDI controller and an Ethernet
controller, your site may be configured so that the FDDI ring attached
to the FDDI controller and the Ethernet segment attached to the
Ethernet controller are bridged by a 10/100 LAN bridge
(FDDI-to-Ethernet). In this configuration, it is impossible to run LAT
over both controllers.
In such a configuration, you must run LAT and DECnet over the same
controller if SCSSYSTEMID is not 0. If you fail to do so, DECnet starts
first, which in turn causes the LAT startup on the other controller to
fail. This failure occurs because LAT startup tries to use the
AA-00-04-00-xx-xx address (the DECnet LAN address) but is prevented
from doing so by the data link layer. The LAT startup fails because
DECnet is already using this address on a different controller. (In a
single logical LAN, all data link addresses must be unique. In this
setup, both controllers try to use the same address, which is then not
unique.)
The following command (which creates the LAT link) also fails because
the LAN driver tries to use the address based on SCSSYSTEMID:
LATCP> CREATE LINK LAT$LINK_2 /NODECNET
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If SCSSYSTEMID is set to 0, configuring LAT and DECnet on different
controllers is possible. However, in a cluster environment, SCSSYSTEMID
cannot be set to 0.
/DEVICE=device-name
Specifies the LAN controller device name for a LAT data link (for
example, XEB0:). Only one LAT data link can be associated with a LAN
controller. If you enter the CREATE LINK command without the /DEVICE
qualifier, LATCP attempts to find an available controller by using a
list of possible LAT data link device names. HP recommends that you
specify a default device name by defining the LAT$DEVICE logical name.
/LOG
/NOLOG (default)
Specifies whether LATCP displays a message confirming that the link was
created. If you do not specify the /LOG or /NOLOG qualifier, the
default is that no message will be displayed.
/STATE=option
Specifies whether the link will be available for use.
STATE can have two options:
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ON
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Specifies that the created link will be available for use with the LAT
protocol running.
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OFF
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Specifies that the created link will not be available for use.
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If you do not specify the /STATE=option qualifier, the default
is that the created link will be available for use (ON).
Description
The CREATE LINK command creates a link, or connection, for an OpenVMS
node and a local area network (LAN) device (for example, an Ethernet or
FDDI controller) and assigns a name to that link. An OpenVMS node can
have eight LAN links. Each link must operate on a separate LAN
controller and have its own LAN hardware.
If you do not explicitly create a link with this command before
entering the SET NODE/STATE=ON command, LATCP automatically creates a
link for you. LATCP names the link LAT$LINK and assigns it to the first
available LAN controller or LAT$DEVICE, if defined. To establish
additional links, use the CREATE LINK command.
Whenever you create a link, specify the LAN controller device name.
Use the SET LINK command to modify link characteristics.
Example
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LATCP> CREATE LINK NETWORK_A /DEVICE=XEB0: /STATE=ON
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This command creates an Ethernet link named NETWORK_A. It specifies the
Ethernet controller device XEB0 for that link. The link will be
available for use.
CREATE PORT
Creates a logical port on your local node that connects with a remote
device on a terminal server. Alternatively, this command creates a
logical port on your local node that connects 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
CREATE PORT [port-name]
Parameter
port-name
Specifies the port name in the form LTAn:, where n is
a unique number from 1 to 9999. If the port you specify already exists,
LATCP returns the following error message:
%LAT-W-CMDERROR, error reported by command executor
-SYSTEM-F-DUPLNAM, duplicate name
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If you do not specify the port name, you must specify the /LOGICAL
qualifier.
Notes
When creating a port, note the following points:
- HP recommends that you assign a logical name when creating a port,
instead of specifying a specific LTA device.
- 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.
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Qualifiers
/APPLICATION
Specifies that a logical port on your node is an application port. It
can be used to connect to a remote device (typically a printer) on a
terminal server or to a dedicated port on another LAT service node.
If you do not specify a port type, the default port type is APPLICATION.
Note
By default, LATCP creates application LAT devices with the HANGUP
terminal characteristic. However, if you want to apply the NOHANGUP
characteristic to application LAT devices, you can do so by entering
specific LATCP and DCL commands. For example:
$ LCP :== $LATCP
$ LCP CREATE PORT LTA1234
$ LCP SET PORT LTA1234 /APPLICATION /NODE=terminal-server /PORT=server-port
$ SET TERMINAL LTA1234 /PERMANENT /NOHANGUP
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Note that you can insert the SET TERMINAL command in the
SYS$MANAGER:LAT$SYSTARTUP.COM file (enter the command for each LAT
device that requires the NOHANGUP characteristic).
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/DEDICATED
Specifies that a logical port on your local node is
dedicated to an application service. When users on a terminal server
(or on another node that supports outgoing connections) request a
connection to this service name, they are connected to the dedicated
port. Refer to the HP OpenVMS I/O User's Reference Manual for a description of programming an
application service.
After creating a dedicated port on a node, use the SET PORT /SERVICE
command to map this port to a service.
/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 was
created. If you do not specify the /LOG or /NOLOG qualifier, the
default is that no message will be displayed.
/LOGICAL=(NAME=logical-name[,TABLE=table][,MODE=mode])
Specifies a logical name to be associated with the actual name of the
created port. You must specify a logical name if you do not specify a
port name.
Note
If you have sufficient privileges to create a port, but lack the
privilege to assign a logical name, the port will still be created.
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You can specify one of the following options for the TABLE keyword:
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GROUP
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Places the logical name in the group logical name table. You must have
GRPNAM or SYSPRV privilege to place the logical name in the group
logical name table.
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JOB
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Places the logical name in the jobwide logical name table.
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PROCESS
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Places the logical name in the process logical name table. This is the
default.
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SYSTEM
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Places the logical name in the system logical name table. You must have
SYSNAM or SYSPRV privilege to place a name in the system logical name
table.
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You can also specify the name of a specific table. For example, you
could specify LNM$PROCESS, which would be the equivalent of specifying
PROCESS.
Options for the MODE keyword are:
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EXECUTIVE
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Creates an executive mode logical name. You must have SYSNAM privilege
to create an executive mode logical name.
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SUPERVISOR
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Creates a supervisor mode logical name.
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USER
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Creates a user mode logical name.
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The access mode associated with the logical name is determined by
maximizing the access mode of the caller with the access mode specified
by the MODE keyword: the mode with the lower privilege is used.
You cannot specify an access mode with a privilege higher than that of
the table containing the logical name. However, if your process has
SYSNAM privilege, then the specified access mode is associated with the
logical name regardless of the access mode of the caller.
If you omit the MODE keyword, the access mode of the caller is
associated with the logical name.
Description
The CREATE PORT command creates a logical LAT port for your local node.
You can set up the port as an application port that is later mapped to
a remote printer (or other device) on a server, or you can set up the
port to be mapped to a dedicated port on a remote LAT service node. See
Example 1.
Alternatively, you can set up the port as a dedicated port for a
special service on a LAT service node. See Example 2.
You can also create the port as a limited port, using the /LIMITED
qualifier.
After creating a port, use the SET PORT command to associate (map) the
port with a queue or a service. (See the discussion that follows
Example 1.) Ordinarily, you create and set ports in the LAT
site-specific startup procedure, LAT$SYSTARTUP.COM. Refer to the
HP OpenVMS System Manager's Manual for more details.
Note
When using the CREATE PORT command to create an application port (for
example, CREATE PORT LTA5001: /APPLICATION), you might receive an error
message similar to the following one:
%LAT-W-CMDERROR, error reported by command executor
-SYSTEM-F-DUPLNAM, duplicate name
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This error occurs because the LAT application port that you are trying
to create has already been created by some other application. That
other application could be LATCP itself because LATCP's port,
LATCP$MGMT_PORT, is used to communicate with LTDRIVER.
You can avoid creating duplicate ports in two ways:
- Use the SET NODE/DEVICE_SEED command to move the lower boundary of
the device unit number range beyond the LTA devices that you are
intending to use as application ports. (By default, LTA device units
that originate from the $ASSIGN system service to LTA0: have unit
numbers that fall within a range from 1 through 9999.) For example, if
you know that all LTA devices from LTA7000: onward are not used as
application ports, you could enter the following commands:
LATCP> SET NODE/DEVICE_SEED=7000
LATCP> CREATE PORT LTA5001:/APPLICATION
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.
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LATCP> CREATE PORT LTA5010:/APPLICATION
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For more information, see the description of the /DEVICE_SEED qualifier
in the SET NODE reference section.
- Execute the LATCP command SET NODE/STATE=ON (either interactively
or in a program) before any LTA application or dedicated ports are
created. Because every LATCP management port (LATCP$MGMT_PORT) created
by the previous LATCP invocation is deleted, no conflict exists with
LAT application ports or newly created dedicated ports.
For more
information, see the description of the /STATE qualifier in the SET
NODE reference section.
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Examples
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LATCP> CREATE PORT LTA22: /APPLICATION
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This command creates an application port named LTA22: on a service
node. You can associate the port with a specific printer on a terminal
server (use the SET PORT /NODE /PORT command) or with a set of printers
on a terminal server (use the SET PORT /NODE /SERVICE command). Or, you
can associate the port with a dedicated port on a remote service node.
In this case, use the SET PORT /NODE /SERVICE command, where the
/SERVICE qualifier specifies an application service associated with a
dedicated port on the remote node. See the examples for the SET PORT
command.
| #2 |
LATCP> CREATE PORT LTA21: /DEDICATED
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This command creates the LTA21: port. It will be used as a dedicated
port that offers a specific service rather than a general timesharing
service.
| #3 |
LATCP> CREATE PORT /LOG /APPLICATION -
_LATCP> /LOGICAL=(NAME=MAIL_PORT, TABLE=PROCESS, MODE=SUPERVISOR)
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This command creates an application port. It assigns the name of the
new port to the specified logical name (MAIL_PORT). The logical is
created as a supervisor mode logical name in the LNM$PROCESS_TABLE
logical name table. LATCP displays a confirmation message.
| #4 |
$ LCP :== $LATCP
$ LCP CREATE SERVICE/LIMITED ONLY_ONE
$ LCP CREATE PORT/LIMITED LTA1234:
$ LCP SET PORT LTA1234: /SERVICE=ONLY_ONE
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This series of commands creates a limited service that allows only one
user to log in to the system through that service. When a user connects
to service ONLY_ONE by responding to the terminal server prompt
(Local>), the user is assigned port LTA1234 and then prompted for
the user name. Any user who attempts to connect to the same service
while LTA1234 has a user logged in receives the "service in
use" message.
CREATE SERVICE
Creates a service on a service node. You must have OPER privilege to
use this command.
Format
CREATE SERVICE [service-name]
Parameter
service-name
Specifies a LAT service name. By default, a service name is the name of
the local node you defined with the SET NODE command.
The service name can be from 1 to 16 ASCII characters in length. The
characters allowed are as follows:
- Alphanumeric characters: A--Z, a--z, 0--9
- A subset of the international character set: ASCII codes 192--253
- Punctuation characters: dollar sign ($), hyphen (-), period (.),
and underscore (_)
Qualifiers
/APPLICATION
Specifies that the created service is an application service. An
application service offers a specific application on the service node
rather than a general interactive service. You can define a dedicated
port for the service by using the CREATE PORT and SET PORT commands.
/IDENTIFICATION[="identification-string"]
Describes and identifies a service. Service nodes include the
identification string in service announcements. A service node
announces its services at regular intervals established with the SET
NODE command. Entering the LATCP SHOW NODE command or the DECserver
SHOW NODE command generates a display that includes this identification
string. By default, the identification string is a translation of
SYS$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 ("").
/LIMITED
Specifies that the service is a limited service, using devices assigned
the limited characteristic and associated with (mapped to) this limited
service. This qualifier is used in conjunction with the SET PORT
/LIMITED command.
/LOG
/NOLOG (default)
Specifies whether LATCP displays a message confirming that the service
was created. If you do not specify the /LOG or /NOLOG qualifier, the
default is that no message will be displayed.
/STATIC_RATING=rating
/NOSTATIC_RATING
Enables or disables dynamic service ratings. A dynamic service rating
means that a LAT algorithm calculates the availability of a service
dynamically, based on the overall level of activity of the node that
offers the service and the amount of memory. When a terminal server or
node requests a connection to a service that is offered on two or more
service nodes, the requesting node selects the service node with the
highest (most favorable) service rating. This selection process is
called load balancing.
The dynamic service rating, which is the default, is usually adequate
for efficient load balancing on the LAT network. However, when
necessary, you can use the /STATIC_RATING qualifier to disable dynamic
service ratings so that you can specify a static (fixed) rating. That
static rating value does not change until the dynamic service rating is
reenabled.
Use the static rating to direct users away from or toward your node
temporarily. Static ratings range from 0 to 255. Specify a low value to
make the local service node less likely to be used; specify a high
value to make the local service node more likely to be used.
If you do not specify either the /STATIC_RATING or /NOSTATIC_RATING
qualifier, the default is that the LAT software uses the dynamic
service rating.
Limited and application services do not rely exclusively on the
dynamically calculated service rating. Instead, they use a portion of
the dynamic rating based on how many ports are available for the
service. For example, if a limited service has 50 percent of its ports
available, the dynamic service rating will be scaled, halved, and then
added to 105. When ports are available, the rating will always be above
the value 105.
When all ports for a limited or application service are in use, the
rating will be based on the scaled dynamic rating and the number of
free queue slots on the local node. The rating will always be less than
90.
This rating procedure for limited and application services follows the
terminal server rating algorithm for services and available ports that
the service offers, while at the same time taking into account the
availability of the node (which is the factor used to calculate the
dynamic rating).
If your system is licensed for a specific number of units (where only a
fixed number of users can log in to the system regardless of how the
login limit is set), then all dynamic ratings become 0 when all OpenVMS
license units have been consumed. (This forces all node service ratings
to the lowest possible value when logins are not possible because all
OpenVMS license units have been consumed.)
Note as well that the LAT software transmits a service announcement
message when a user logs in to or out of the system. This allows the
system to more quickly provide information about service rating changes
that result from a login or logout operation.
Description
The CREATE SERVICE command creates a service that a service node offers
to terminal servers (and nodes that support outgoing connections) on
the LAT network.
The service can be a general timesharing service that offers all the
resources of the service node, or it can be an application service that
offers a specific application on the service node. The number of
services that you can create with the CREATE SERVICE command depends on
the availability and capability of specific resources.
The following table lists the maximum number of services your node can
offer and still be recognized by the DECserver terminal server,
depending on the model number:
| DECserver Terminal Server |
Maximum Number of Services
Offered by Node |
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Model 100
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8
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Model 200
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64
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Model 300
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64
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Model 90TL
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64
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Model 700
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64
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Model 500
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127
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Note
If you create more than the maximum number of services supported by a
specific DECserver model, that server will not recognize your node.
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To create an application service, use the /APPLICATION qualifier. In
addition, define a dedicated port by using the CREATE PORT and SET PORT
commands. Most often, a system manager creates services in
LAT$SYSTARTUP.COM, the site-specific LAT configuration procedure.
(Refer to the HP OpenVMS System Manager's Manual for further information about creating an
application service. The HP OpenVMS I/O User's Reference Manual shows how to program an
application service.)
Several service nodes can share one service name. A shared service name
is especially useful in a cluster environment because it allows the
cluster to be known by a single cluster name. When a user logs in, the
terminal server connects to the least busy node offering that service.
You can modify the service characteristics with the SET SERVICE command.
Examples
| #1 |
LATCP> CREATE SERVICE/STATIC_RATING=195 SALES
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This command creates the service SALES on a service node. This command
assigns a static rating of 195 so terminal servers (and nodes that
support outgoing connections) can assess the availability of services
on the node.
| #2 |
LATCP> CREATE SERVICE/APPLICATION GRAPHICS
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