OSI/AS Configuration and Management Manual

OSI/AS Subsystem Description

OSI/AS Configuration and Management Manual—424119-001

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Upward Information Flow

Incoming TPDUs are received by the TSP process and returned to the TAPS process in

file-system calls. Errors (such as 140) are returned when the TSP subdevice detects an

error.

The following PTrace example shows an incoming CR-TPDU:

State Machine

The Transport Layer protocol (described in the ISO 8073 specification) consists of key

states and events that ensure reliable end-to-end data transfer. The protocol requires, in

part, that a connect confirm TPDU (CC-TPDU) follows a CR-TPDU, that data transport

TPDUs (DT-TPDUs) require acknowledge TPDU (AK-TPDUs) in some classes, and

that a disconnect confirm TPDU (DC-TPDU) follows a disconnect request TPDU

(DR-TPDU).

The following two PTrace records show what happens when the TSP process receives a

CR-TPDU. Record #47 on the trace shows that a class 2 CR-TPDU has been received

(E4^C02^TP^CR) and that the TSP process must determine whether it is acceptable

(E4^C02^CR^ACCEPTABLE). Record #48 shows that the TSP process has gone to the

next state to notify the user (A4^SND^CONNIND):

17:11:53.790 >000.010 #46 L4 TPDU IN

CR-TPDU CDT: 4 Dst: 0 Src: 2 Class: 2 Ext-Frmt: NO Exp-Flwctl: YES

Calling TSAP:(hex) 4444 4444 02 Called TSAP:(hex) 4444 4444 01 TPDU Size: 512

Version: 1

17:11:53:.00 >000.010 #47 L4 SM

TCB: 2 Class: 2 S4^CO2^WFCR :E4^CO2^TP^CR =>A4^CHK^CR^ACCEPTABLE SU:

#Z000006

17:11:53:800 >000.000 #48 L4 SM

TCB: 2 Class: 2 S4^CO2^WFCR1 :E4^CO2^CR^ACCEPTABLE =>A4^SND^CONNIND SU:

#Z000006