OSI/TS Configuration and Management Manual

OSI Transport Services

OSI/TS Configuration and Management Manual—424831-001

5-5

Corrupted TPDUs

If OSI/TS receives data from the subnetwork that cannot be interpreted as a TPDU for a

particular transport connection, it discards the data.

If OSI/TS receives a TPDU that can be associated with a connection but is invalid, it

transmits an error TPDU (ER-TPDU). In class 0, the data area of the ER-TPDU

contains a part of the received TPDU up to and including the octet in error. In classes 1

through 4, the data area includes the entire invalid TPDU.

When OSI/TS receives an ER-TPDU, it initiates the release procedure appropriate for

the protocol class. However, if the ER-TPDU is in response to a connect-request TPDU

(CR-TPDU), the connection is considered released.

Frozen Connection Identifier References

During connection establishment, OSI/TS assigns a locally unique identifier to the

transport connection. (See the discussion of SRC-REF and DST-REF in Section 7,

NonStop Kernel File-System Interface.) When the connection is released, OSI/TS does

not use the same identifier for a new connection until the configured time period has

elapsed. (The time period can be set by using SCF.) This procedure ensures that new

transport connections do not receive TPDUs intended for previous connections. OSI/TS

uses this procedure in every protocol class.

Table 5-3. Error Detection and Recovery

Service Class 0 Class 1 Class 2 Class 3 Class 4

Corrupted TPDU handling YYYYY

Frozen references YYYYY

Data TPDU numbering NYYYY

Reassignment after failure NYNYY

Resynchronization NYNYY

Retention of TPDUs until

acknowledged

NYNYY

Retransmission timeout NNNNY

Resequencing NNNNY

Inactivity control NNNNY

Y Yes, OSI/TS provides the service

N No, OSI/TS does not provide the service.