Link Configuration: LAPBMUX Link Data

Fields

Physical path

The physical path of the LAPBMUX (Sync MUX) card.

The basic formula for deriving the physical path is:

A Class PathNumber /1. card port number

N Class PathNumber /0/1. card port number

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

Card cage 0: PathNumber = 0/2

Card cage 1: PathNumber = 0/6

(b) / is the slash character (not the division sign), (c) portnum is the card port number used, it's value is from 0 to 7.

Examples:

A Class — PathNumber /1. port num

If the MUX card is in slot 0/6/2 and if using card port number 4, then the physical path is: 0/6/2/1.4

N Class — PathNumber /0/1. port num

If the MUX card is in slot 0/6 and using card port number 2, then the physical path is: 0/6/0/1.2

A valid hardware path should confirm the following:

1. Path is non-empty and fits the field (<= 32 chars).

2. Path begins and ends with a digit.

3. Path contains only digits, "/", or "." characters.

4. Path contains no occurrences of "//", "..", "./", "/."

5. Other than that, ANY other combination of characters should be accepted, out to the full 32 characters.

Modem Type

V.25bis is a ITU-T specification for a modem command language and overall modem behavior. It includes both asynchronous and synchronous command interfaces.

Hayes is the dialing standard for async modems. Hayes includes V.25bis in its ULTRA modems to support synchronous out-dial facilities of host computers and to support the evolution of synchronous communications software on PCs.

Select the right modem type or 0 for leased/direct line.

Max receive bytes

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: 1024-4096 Bytes

Response timer T1:

Response timeout in milliseconds. 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 the speeds greater than or equal to 9600 bits per second and four seconds for line speeds less than 9600 bits per second.

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

Default value: 3000

Range: 3000 to 1260000ms

Speed

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

Default value: 56000 bits/second

Range: 1200-2048000 bits/second

Retry count N2:

This field specifies the maximum number of times to retransmit a frame if the T1 timer expires. The recovery procedure mentioned in LAPBMUX 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

Physical interface:

RS-232 is a standard electrical lnterface between Data Terminal Equipment (DTE) and Data Circuit-Termination Equipment (DCE) such as modems or DSUs. RS-232 is used for asynchronous data transfer as well as synchronous links such as SDLC, HDLC, Frame Relay and X.25.

The V.35 interface was originally specified by CCITT as an interface for 48kbps line transmissions. It has been adopted for all line speeds above 20kbps.

Select the interface that matches the other end.

Connect timeout:

During link initialization, this value specifies the amount of time the MUX card will wait for a response from the remote station. If this time is exceeded, it is assumed that the remote station is not responding.

Default value: 900

Range: 5-900 seconds or 0 (0 means disabled)

Adapter timeout:

This is a handshake sequence between the host and its MUX card.

Default value: 10

Range: 5-900 seconds or 0

Clock source:

Specifies the origin of the synchronous timing signals. If the parameter is set to Internal, the adapter supplies the required timing signals. If the parameter is set to External, an external network device supplies the required timing signals. If the adjacent link station is providing the clock source, set this parameter to External.

Default value: external (1)

Options: internal (0), external (1)

Auto hangup timer:

Intended primarily for use with certain European public telephone systems. If set, the driver will periodically attempt to hang up the local modem phone line, then resume awaiting a connection. This recovers from situations in which a human or incompatible modem accidentally dialed in during the time period, but the local modem failed to hang up on its own after failing to establish a connection. If a connection is successfully established, the timer is cancelled. When zero, the feature is disabled.

Default: 0

Range: 5-900sec

Local mode:

If the node being configured is DCE, then the node at the other side must be DTE. If the node being configured is DTE then the node at the other side must be DCE.

Options: 5 = DTE, 6 = DCE

Data encoding:

NRZ: Indicates Non-Return to Zero coding

NRZI: Indicates Non-Return to Zero Inverted coding

NRZI coding unlike NRZ coding specifies that the signal condition does not change for transmitting a binary 1 while a binary 0 causes change of state.

Since asynchronous operation requires that the receiver sampling clock be derived from the received data, NRZI encoding plus zero bit insertion (for every consecutive 5 one (1) bits) make the design of clock recovery circuitry easier.

Default: NRZ (0)

Options: NRZ (0), NRZI (1)

Trace at startup:

Enter Y (YES) to enable link tracing, N (NO) otherwise. This value can be overridden with the LINKCONTROL command. If enable link tracing is selected, a trace file name is required.

For best performance, do not enable tracing.

Default value: N

Trace file:

Required if link trace is enabled. Name of the disk file where you want to record tracing. Must be a valid MPE 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.

Modulo count:

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

Default: 8

Range: 8 or 128

Window size K:

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 call the Level 2 window size.

Default value: 7

Range 1-127