Chapter 5. Reconfiguring LAT Operating Parameters
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## Chapter 5. Reconfiguring LAT Operating Parameters

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:

- “The LAT Configuration Utility Menu”

- “Setting Ethernet Parameters”

- “Setting LAT Node Identification Parameters”

- “Setting LAT Configuration Limits”

- “Setting Circuit Parameters”

- “Setting Session Parameters”

- “Setting Host-initiated Parameters”

- “Setting Advertised Service Parameters”

- “Setting Learned Service Parameters”

- “Setting STREAMS Configuration Parameters”

- “Summary of 4DLT Configuration Parameters”

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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