Link Configuration: LAP-B Link Data

Fields

Physical path

The physical path of the Programmable Serial Interface (PSI) card.

The basic formula for deriving the physical path is 4 x slot number. (Example: 4 x 10 = 40.) For systems with dual card cages, you must also specify a path number for the card cage, as follows:

PathNumber/(4 X SlotNumber)

where (a) PathNumber is a number corresponding to the card cage the PSI is in:

Card cage 0: PathNumber = 2

Card cage 1: PathNumber = 6

(b) / is the slash character (not the division sign), (c) the parentheses are used to set off an arithmetic formula (they are not entered as part of the Physical Path value), (d) X is the multiplication sign (not the character X), and (e) SlotNumber is the number of the slot, within the card cage, the PSI is in.

Examples:

If the PSI is in card cage 0, slot number 4, the Physical Path is 2/16

(PathNumber, slash character, 4 multiplied by 4).

If the PSI is in card cage 1, slot number 3, the Physical Path is 6/12

(PathNumber, slash character, 4 multiplied by 3).

If you are unsure of the slot location or of the physical path number to configure for your system, see your system documentation or consult your Hewlett-Packard service representative.

Connect timeout

(HP modifiable.) During link initialization, this value specifies the amount of time the PSI will wait for a response from the remote station. If this time lapse is exceeded, it is assumed that the remote station is not responding.

Default value: 900

Range: 60-900 seconds or 0 (0 means disabled)

Local timeout

This is a handshake sequence between the host and its PSI card. It is useful to prevent the PSI card from keeping a line up when the system goes down.

Default value: 60

Range: 30-900 seconds or 0 (0 means disabled)

Modulo count

This parameter specifies a window representing the number of frames that can be outstanding.

Default value: 8

Range: 8 or 128

LAP-B parameter T1

(HP modifiable.) Response timeout in hundredths of a second. This is the maximum amount of time that the transmitter should wait for an acknowledgment before initiating a recovery procedure. This delay must account for three frame transmissions and two frame-processing delays. An approximation of this value is three seconds for line speeds greater than or equal to 9600 bits per second and four seconds for line speeds less than 9600 bits per second.

The formula for the approximation in hundredths of a second is the following:

400 x [(buffer size x 8)/line speed]

The configuration validation program will issue a warning if the set value does not comply to this specification.

Default value: 300

Range: 5 to 1200 hundredths of seconds or 0 (0 means disabled)

LAP-B parameter K

(HP modifiable.) This parameter specifies the maximum number of sequentially numbered frames that the configured node may have unacknowledged at any given time. This parameter is also called the Level 2 window size.

Default value: 7

Range: 1-7 if modulo count=8; 1-127 if modulo count=128

LAP-B parameter N2

(HP modifiable.) This field specifies the maximum number of times to retransmit a frame if the T1 timer expires. The recovery procedure mentioned in LAP-B parameter T1 usually refers to the retransmission of the oldest unacknowledged frame. The value of N2 specifies the total number of times that the T1 timer expires and a frame is retransmitted in determining that the other side is not responding.

Default value: 20

Range: 1-255 retries

Buffer size

Layer 3 through 7 frame size. This is the amount of data that a user of OSI Levels 3 through 7 can put in that frame. It does not include Level 2 header or trailer information. This parameter is used to configure memory buffers.

Default value: 1024

Range: 32-1024 Bytes

Local mode

If the node you are configuring is a Hewlett-Packard computer operating across a point-to-point link, enter 11 (the default). HP computers at both ends of a point-to-point link must both be configured as HP point-to-point. If the remote node is a non-HP node and the local station is acting as DTE, enter 5. If the remote node is a non-HP node and the local station is acting as DCE, enter 6. If the node you are configuring is DCE, then the node at the other side must be DTE. If the node you are configuring is DTE, then the node at the other side must be DCE.

Default value: 11

Range: 5 = DTE, 6 = DCE, 11 = HP Point-to-Point

Transmission speed

This is the line-transmission speed in bits per second. It may be overridden by whichever device is providing clocking. The PSI simply transmits using the provided clock source, whether it is the HP e3000's CPU clock or a modem.

Default value: 56000

Range: 1200, 2400, 4800, 9600, 19200, 38400, 56000, or 64000 bits/second

Trace at startup

(HP modifiable.) Enter Y (YES) to enable link tracing at link startup, N (NO) otherwise. This value can be overridden with the LINKCONTROL command.

If you do enable link tracing, you are required to enter a trace file name. For best performance, do not enable tracing.

Default value: N

Trace file name

(HP modifiable.) Required if link trace is enabled. Name of the disk file where you want to record tracing. Must be a valid file name. Enter the file name in the format filename.groupname.acctname. The fully qualified file name can be as many as 26 characters.

Lockwords are not allowed for trace files.

Do not specify the same file name with the NMMGR configuration as specified with the LINKCONTROL command. Only one active trace is allowed per link.