1 – LINK
Creates the LAT data links, which are connections to LAN devices,
such as Ethernet or FDDI (fiber distributed data interconnect)
controllers, that you want your node to use. You must have OPER
privilege to use this command.
Format
CREATE LINK link-name
1.1 – 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:
o Alphanumeric characters: A-Z, a-z, 0-9
o A subset of the international character set: ASCII codes 192-
253
o 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.
1.2 – Qualifiers
1.2.1 /DECNET
/DECNET
/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:
(1024 * a) + n
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:
o 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).
o 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
Digital).
o 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
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.
1.2.2 /DEVICE
/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. Digital
advises that you specify a default device name by defining the
LAT$DEVICE logical name.
1.2.3 /LOG
/LOG
/NOLOG
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.
1.2.4 /STATE
/STATE=option
Specifies whether the link will be available for use. STATE can
have two options:
ON Specifies that the created link will be available for use
with the LAT protocol running.
OFF Specifies that the created link will not be available for
use.
If you do not specify the /STATE=option qualifier, the default is
that the created link will be available for use (ON).
1.3 – Example
LATCP> CREATE LINK NETWORK_A /DEVICE=XEB0: /STATE=ON
The CREATE LINK command in this example creates an Ethernet
link named NETWORK_A. It specifies the Ethernet controller
device XEB0 for that link. The link will be available for use.
2 – 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]
2.1 – Parameter
port-name
Specifies the port name in the form LTAn:, where n is a unique
number from 1 through 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
If you do not specify the port name, you must specify the
/LOGICAL qualifier.
NOTES
When creating a port, note the following:
o Digital recommends that you assign a logical name when
creating a port, instead of specifying a specific LTA
device.
o 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.
2.2 – Qualifiers
2.2.1 /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
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).
2.2.2 /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. See the 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.
2.2.3 /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).
2.2.4 /LOG
/LOG
/NOLOG
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.
2.2.5 /LOGICAL
/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.
You can specify one of the following options for the TABLE
keyword:
GROUP 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.
JOB Places the logical name in the jobwide logical name
table.
PROCESS Places the logical name in the process logical name
table. This is the default.
SYSTEM 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.
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:
EXECUTIVE Creates an executive mode logical name. You must have
SYSNAM privilege to create an executive mode logical
name.
SUPERVISOR Creates a supervisor mode logical name.
USER Creates a user mode logical name.
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.
You can also create the port as a limited port, using the
/LIMITED qualifier.
2.3 – Examples
1.LATCP> CREATE PORT LTA22: /APPLICATION
The CREATE PORT command in this example 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
The CREATE PORT command in this example 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)
The CREATE PORT command in this example 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
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.
3 – SERVICE
Creates a service on a service node. You must have OPER privilege
to use this command.
Format
CREATE SERVICE [service-name]
3.1 – 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:
o Alphanumeric characters: A-Z, a-z, 0-9
o A subset of the international character set: ASCII codes 192-
253
o Punctuation characters: dollar sign ($), hyphen (-), period
(.), and underscore (_)
3.2 – Qualifiers
3.2.1 /APPLICATION
Specifies that the created service is an application service. An
application service offers a specific application on the service
node rather than a general interactive service. You can define a
dedicated port for the service by using the CREATE PORT and SET
PORT commands.
3.2.2 /IDENTIFICATION
/IDENTIFICATION[="identification-string"]
Describes and identifies a service. Service nodes include the
identification string in service announcements. A service node
announces its services at regular intervals established with the
SET NODE command. Entering the LATCP SHOW NODE command or the
DECserver SHOW NODE command generates a display that includes
this identification string. By default, the identification string
is a translation of SYS$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 (").
3.2.3 /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 (see example).
3.2.4 /LOG
/LOG
/NOLOG
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.
3.2.5 /STATIC_RATING
/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% 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 then 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.
3.3 – Examples
1.LATCP> CREATE SERVICE/STATIC_RATING=195 SALES
The CREATE SERVICE command in this example 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
This command creates the service GRAPHICS on the local node.
Use the CREATE PORT/DEDICATED and SET PORT/SERVICE=GRAPHICS
commands to create a port that is dedicated to this service.
3.$ LCP :== $LATCP
$ LCP CREATE SERVICE/LIMITED ONLY_ONE
$ LCP CREATE PORT/LIMITED LTA1234:
$ LCP SET PORT LTA1234: /SERVICE=ONLY_ONE
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.