IBM 3745 Problem Determination Manual page 272

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Problems on One Line Only (LlC1 to LIC4)
CCITT V.25bis Switched - Modem Attachment
The V.25bis is a
p~otocol
which allows to combine on one physical interface (DTE
- DCE) the call establishment and the data transmission. This eliminates the
need for a second physical port previously required by the V.25 protocol.
• The connection process can only be done in SDLC or SIS mode.
• The data transfer can be done in SDLC, SIS, or SSC mode.
Commands sent by NCP to the modem
• Call request commands (X'OD')
The V.25bis Call Request command is used to make an outgoing call. This
command supports two modes of addressed call:
CRN Call Request with Number
The dial digits are sent to the modem with the command.
CRI Call Request with number and Identification number
The dial digits are sent to the modem with the command qnd an
identification number of the caller.
Commands sent by NCP to the scanner
• Monitor incoming call commands (X'OE')
The V.25bis Monitor Incoming Call command is sent by NCP to the scanner
to allow incoming call on the line.
• Clear request commands (X'OF')
The V.25bis Clear Request command is used by NCP to inform the scanner
to clear the line.
A summary of NCP commands and modem status answers is shown on
Table 9-1 on page 9-22.
Conditions of Command Retry
NCP will perform a retry if the following statuses are received from the modem.
• X'80' Time out.
• X'Fe' Calt failure indication (except for the ELCS code X'07') Forbidden call.
• X'EC ' Call collision
Note: For X'80' and X'FC' the NCP waiting duration depends on the value
defined in the keyword REDIAL of the NCP LINE statement.
Delayed call indication X'EA'
The modem return the status X'EA' after several unsuccessful calls. It also
returns 3 bytes that contain the number of minutes that NCP should wait before
trying another call. This information is passed to NetView to be included in a
generic alert.
Chapter 9. lIC and Line Problems (LSS)
9-21