Chapter 5. Reconfiguring LAT Operating Parameters

Chapter 5. Reconfiguring LAT Operating Parameters
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This chapter explains how to change the internal parameters of 4DLT using lati, an interactive configuration utility. The lati menu and each of its options are described in this chapter:

Some of the parameters you set with lati can also be set using the slcp utility. Since changes you make with lati will only take effect after you stop and restart 4DLT, you might prefer to use slcp to change these parameters if a 4DLT shutdown will disrupt system users. See Table 5-1 at the end of this chapter for slcp command equivalents to using lati.

The LAT Configuration Utility Menu

To start the LAT configuration utility, you enter the lati command at the IRIX prompt as the superuser. After your entry, the lati menu is displayed:

# lati

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing
a number from 1 to 9 or type `q' to quit:

Selecting Menu Options

To select a lati menu item, type the number of the item and press <Enter>. After your selection, lati displays each parameter associated with your selection and the parameter's current value. You can take three actions on any parameter:

To change a parameter value, enter a new value and press <Enter>.
To retain the current parameter value, press <Enter>.
To set a null string, press <Esc><Enter>.

Putting Your Changes into Effect

The changes you make with the lati utility are written to the /usr/etc/lat/latconfig file. The changes take effect when the new copy of latconfig is copied into main memory. To write a new copy of latconfig to memory, you must stop and restart latd (see “Stopping and Restarting 4DLT”).

Setting Ethernet Parameters

To set LAT Ethernet interface parameters, use item 1 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing
a number from 1 to 9 or type `q' to quit: 1

Item 1 on the lati menu provides these parameters:

NET_DEVICE

Specifies the pathname to the LAT network interface.

4DLT installation sets NET_DEVICE to /dev/snif, which uses either the primary network interface (see “The Default Network Interface for LAT”) or a specified alternate interface (see “Starting 4DLT with an Alternate LAN Interface”).

Do not change the value of NET_DEVICE; it should remain set to /dev/snif.

HS_MULTI_ON

Switches the IRIS system between dual purpose and general purpose operation.

Set to 1, the default setting, to operate the IRIS system as a service node and terminal server concurrently.

Set to 0 (zero) to operate the IRIS system as a service node only. This setting disables the IRIS system's ability to receive and process incoming service announcements, thereby disabling terminal server functions.

Setting LAT Node Identification Parameters

To set LAT node identification parameters, use item 2 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing
a number from 1 to 9 or type `q' to quit: 2

Item 2 on the lati menu provides these parameters:

HS_NODE

Sets the LAT node name for the IRIS host.

4DLT installation sets this to the name contained in the IRIS system's /etc/sys_id file. Keep these guidelines in mind if you change a LAT node name:

The node name must be unique on the LAN.
Node names can contain a maximum of 16 characters.
Valid characters include all alphanumeric characters and the symbols dollar sign ($), period (.), hyphen (-), and underscore (_).
Uppercase and lowercase letters are valid, but lowercase letters are converted for internal operations.

Note: You can set this parameter with the slcp -n command.

HS_IDENT

Is an optional character string that describes the IRIS node to LAT users.

Note: You can set this parameter with the slcp -n command.

HS_FACILITY

Is an optional local facility number used at some LAT network sites.

HS_CPU_RATING

Specifies the CPU rating, a factor that the service node uses in combination with HS_JOB_LIMIT to calculate service ratings.

Valid range is 1 through 100. Set higher to increase service ratings and host usage; set lower to reduce service ratings and host usage. Default setting is -1.

This parameter is not used if dynamic service ratings are enabled (slcp -r is set to -1).

Note: You can set this parameter with the slcp -c command.

HS_JOB_LIMIT

Specifies the maximum number of LAT users on the IRIX system, a factor that the service node uses in conjunction with HS_CPU_RATING to calculate service ratings.

Set to the expected user total—the local terminal server user and remote login service users combined.

Default setting is 50.

Note: You can set this parameter with the slcp -c command.

Setting LAT Configuration Limits

To set LAT configuration limits, use item 3 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing
a number from 1 to 9 or type `q' to quit: 3

Item 3 on the lati menu provides these parameters:

HS_SB_MAXIMUM

Specifies the maximum LAT sessions that can be created on the service node.

Set to 0 (zero), the default setting, for no limit.

Valid range is 1 to 255 sessions.

Note: You can set this parameter with the slcp -m command.

HS_CB_MAXIMUM

Specifies the maximum circuits that can be created to a service node.

Set to 0 (zero), the default setting, for no limit.

HS_ND_MAXIMUM

Specifies the maximum remote nodes learned from the network.

Both terminal server and service node software use this value in establishing virtual circuits.

The default value is 100.

HS_LS_MAXIMUM

Specifies the maximum number of LAT services the terminal server collects from multicast service announcements.

Default setting is 100.

Set to 0 (zero) for no limit. Set to -1 to prevent a terminal server from accepting any learned service information.

HS_QR_MAXIMUM

Specifies the maximum size of the terminal server's queue for host-initiated requests.

Default setting is 32.

Set to 0 (zero) for no limit. Set to -1 to prevent any requests from being queued.

Setting Circuit Parameters

To set circuit parameters, use item 4 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing
a number from 1 to 9 or type `q' to quit: 4

Item 4 on the lati menu provides these parameters:

HS_DLL_MAX

Specifies the maximum size for an outgoing Ethernet packet, not including header.

Default value is 1500 bytes.

Valid range is 576 to 1500 bytes.

To make efficient use of streams buffers, set at 1024.

HS_INP_MAX

Specifies the maximum size for an incoming Ethernet packet, not including header.

Default value is 1500 bytes; this is the recommended setting for Silicon Graphics systems.

Valid range is 576 to 1500 bytes.

HS_CB_MAX_SES

Specifies the maximum number of sessions permitted on a single circuit.

Valid range is 1 to 255.

Default value is 64 sessions.

HS_CB_RETRIES

Specifies the maximum number of attempts the terminal server makes to establish a virtual circuit before it declares a circuit time-out error.

Valid range is 4 to 120 attempts.

Default setting is 8 attempts.

HS_CB_VC_TIMER

Specifies the setting in milliseconds for the virtual circuit timer on the terminal server; virtual circuit messages are sent when the timer reaches 0 (zero).

Valid range is 10 to 1000 milliseconds.

Recommended setting is 80 milliseconds.

Default setting is 80 milliseconds.

Note: You can set this parameter with the slcp -t command.

HS_CB_HD_TIMER

Specifies in milliseconds the time that a service node will wait before responding to a virtual circuit message from a terminal server.

Recommended setting is half the value of the setting on the circuit timer, HS_CB_VC_TIMER, or 40 milliseconds by default.

HS_CB_KA_TIMER

Specifies in milliseconds the intervals at which the terminal server sends keep-alive messages over an idle circuit.

Valid range is 10 to 255 milliseconds.

Recommended setting is 20 milliseconds.

Default setting is 20 milliseconds.

HS_CB_PROGRESS

Specifies in seconds the amount of time the service node will wait for a virtual circuit message before disconnecting the circuit with the terminal server.

Valid range is 0 (zero) to 255 seconds.

Default setting is 60 seconds.

If set to 0 (zero), the virtual circuit will never be disconnected as a result of a message processing time-out.

Setting Session Parameters

To set session parameters, use item 5 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing 
a number from 1 to 9 or type `q' to quit: 5

Item 5 on the lati menu provides these parameters:

HS_CREDITS

Specifies the number of credits (that is, receive buffers) the terminal server allocates per session.

Recommended value is 2 (also the default value).

HS_SB_MAX_DATA

Specifies the maximum size in bytes of an individual virtual circuit message.

Valid range is 1 to 255 bytes.

Recommended setting is 255 bytes.

Reduce to 128 bytes to make efficient use of the 128-byte streams buffer pool.

Setting Host-initiated Parameters

To set parameters on host-initiated requests, use item 6 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing 
a number from 1 to 9 or type `q' to quit: 6

Item 6 on the lati menu provides these parameters:

HS_HI_STS_TIMER

Specifies in milliseconds the time between queue status messages sent by a terminal server during a host-initiated request.

Valid range is 10 to 3600 milliseconds.

Default setting is 60 milliseconds.

HS_HI_CMD_TIMER

Specifies in seconds the time that a service node waits before resending a host-initiated requests to a terminal server.

Recommended value is 1 to 60 seconds.

Default setting is 15 seconds.

HS_HI_CMD_RETRIES

Specifies the number of times the service node will resend a host-initiated request to a terminal server before giving up.

Valid range is 2 to 120 attempts.

Default setting is 10 attempts.

Setting Advertised Service Parameters

To set parameters on advertised services, use item 7 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing 
a number from 1 to 9 or type `q' to quit: 7

Item 7 on the lati menu provides this parameter:

HS_AS_TIMER

Specifies in seconds the interval at which a service node sends out service messages.

Valid range is 10 to 180 seconds.

Default setting is 60 seconds.

Note: You can set this parameter with the slcp -t command.

Setting Learned Service Parameters

To set parameters for learned services, use item 8 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing
a number from 1 to 9 or type `q' to quit: 8

Item 8 on the lati menu provides these parameters:

HS_LE_LS_DUPS

Specifies whether the terminal server should maintain duplicate service names.

Set to 0 (zero) to reject duplicate service names. This setting prevents the selection of services based on service ratings.

Set to 1 (the default) to maintain duplicate service names. This setting allows the terminal server to select services based on its service rating.

HS_LE_ND_RETAIN

Specifies whether the terminal server should display unknown and unreachable services in service listings.

Set to 0 (zero) to omit unknown and unreachable services when displaying the list of services.

Set to 1 (the default) to include unknown and unreachable services when displaying the list of services.

HS_ND_AGE_MAX

Specifies the number of seconds that a terminal server will wait before purging unknown and unreachable services from its database.

Valid range is 0 (zero) to 28800 seconds (8 hours).

The default setting is 18000 seconds (5 hours).

Set to -1 to disable purging of unknown and unreachable services.

Setting STREAMS Configuration Parameters

To set streams configuration parameters, use item 9 on the lati menu:

1. Ethernet device
2. LAT host name, identification
3. LAT configuration parameters, limits
4. Circuit parameters
5. Session parameters
6. Host-Initiated parameters
7. Advertised Service parameters
8. Learned Service parameters
9. Streams configuration

Select a parameter category by typing
a number from 1 to 9 or type `q' to quit: 9

Item 9 on the lati menu provides these parameters:

NET_STREAM_1		Specifies the first (lower) module on the Ethernet stream. Default setting is null (` `).
NET_STREAM_2		Specifies the second (higher) module on the Ethernet stream. Default setting is null `(`` `).
LAT_FDEV		Specifies the LAT device name for login terminals. Default setting is `/dev/ttyl`.
LAT_CDEV		Specifies the LAT device name for outgoing sessions. Default setting is `/dev/lats`.
LAT_STREAM_1		Specifies the first (lowest) module to push onto a session stream. Default value is null (` `).
LAT_STREAM_2		Specifies the second module to push onto a session stream. The default value is null (` `).
LAT_STREAM_3		Specifies the third module to push onto a session stream. Default value is tirdwr (handles STREAMS read/write calls). The read/write module must be pushed onto the stack before the line discipline module.
LAT_STREAM_4		Specifies the fourth (higher) module to push onto a session stream. . Default value is stty_ld (handles line discipline). This module must be the first to appear to the user.

Summary of 4DLT Configuration Parameters

Table 5-1 contains an alphabetical listing of the 4DLT configuration parameters that you can change with lati. .

Table 5-1. Summary of 4DLT Configuration Parameters

Parameter Name	Parameter Function	Default Value	Item on`lati` Menu	`slcp` Equivalent
HS_AS_TIMER	Specifies the interval (in seconds) for multicasting service announcements	60	Item 7	`slcp -t`
HS_CB_HD_TIMER	Specifies time (in milliseconds) a service node waits before responding to terminal servers	40	Item 4	None
HS_CB_KA_TIMER	Specifies interval (in milliseconds) at which a terminal server sends keep-alive messages	20	Item 4	None
HS_CB_MAXIMUM	Specifies maximum number of circuits to a service node	0 (no limit)	Item 3	None
HS_CB_MAX_SES	Specifies the maximum number of sessions on a single circuit	64	Item 4	None
HS_CB_PROGRESS	Specifies time (in seconds) the service node waits for a virtual circuit message before disconnecting a circuit	60	Item 4	None
HS_CB_RETRIES	Specifies the maximum number of attempts a terminal server makes to establish a virtual circuit before declaring a time-out error	8	Item 4	None
HS_CB_VC_TIMER	Specifies the interval (in milliseconds) between virtual circuit messages from the terminal server	80	Item 4	`slcp -t`
HS_CPU_RATING	Sets the CPU rating for a service node	-1 (dynamic ratings)	Item 2	`slcp -c`
HS_CREDITS	Specifies the number of credits the terminal server allocates per session	10	Item 5	None
HS_DLL_MAX	Specifies (in bytes) the size of an outgoing Ethernet packet, excluding headers	1500	Item 4	None
HS_FACILITY	Specifies the local facility number	0	Item 2	None
HS_HI_CMD_RETRIES	Specifies the number of times that a service node resends a host-initiated request	10	Item 6	None
HS_HI_CMD_TIMER	Specifies the time (in seconds) that a service node waits between retries for a host-initiated request	15	Item 6	None
HS_HI_STS_TIMER	Specifies the interval (in milliseconds) between queue status messages sent by a terminal server during a host-initiated request	60	Item 6	None
HS_IDENT	Assigns a description to an IRIS node so LAT users can identify it	none	Item 2	`slcp -n`
HS_INP_MAX	Specifies the maximum size (in bytes) of Ethernet packets, excluding headers	1500	Item 4	None
HS_JOB_LIMIT	Specifies the maximum number of LAT users on an IRIS system (terminal server and service node combined)	50	Item 2	slcp -c
HS_LE_LS_DUPS	Specifies whether a terminal server should maintain duplicate service names	1	Item 8	None
HS_LE_ND_RETAIN	Specifies whether a terminal server should display unknown and unavailable services	1	Item 8	None
HS_LS_MAXIMUM	Specifies the maximum number of services maintained in a terminal server's database	100	Item 3	None
HS_MULTI_ON	Switches an IRIS system between a dual purpose and general purpose LAT node	1 (dual purpose)	Item 1	None
HS_ND_AGE_MAX	Specifies interval (in seconds) at which a terminal server purges unavailable nodes and services from its database	18000 (5 hours)	Item 8	None
HS_ND_MAXIMUM	Specifies the maximum number of nodes maintained in a terminal server's database	100	Item 3	None
HS_NODE	Sets the LAT node name on an IRIS host	name in `/etc/sys_id`	Item 2	`slcp -n`
HS_QR_MAXIMUM	Specifies the maximum size of a terminal server's queue for host-initiated requests	32	Item 3	None
HS_SB_MAX_DATA	Specifies the maximum size of an individual data slot message	255	Item 5	None
HS_SB_MAXIMUM	Specifies the maximum number of sessions that a terminal server or server node will allow	0 (no limit)	Item 3	`slcp -m`
LAT_FDEV	Specifies the device name for LAT login terminals	`/dev/ttyl`	Item 9	None
LAT_CDEV	Specifies the device name for outgoing LAT sessions	`/dev/lats`	Item 9	None
LAT_STREAM_1	Specifies the first (lowest) module to push onto a session stream	null	Item 9	None
LAT_STREAM_2	Specifies the second module to push onto a session stream	null	Item 9	None
LAT_STREAM_3	Specifies the third module to push onto a session stream	tirdwr	Item 9	None
LAT_STREAM_4	Specifies the fourth (highest) module to push onto a session stream	stty_ld	Item 9	None
NET_DEVICE	Specifies the IRIS node's LAT device	`/dev/snif`	Item 1	None
NET_STREAM_1	Specifies the first (lower) module on an Ethernet stream	null	Item 9	None
NET_STREAM_2	Specifies the higher module on an Ethernet stream	null	Item 9	None

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Chapter 4. Performing Routine LAT Maintenance		Glossary