TS Supplement (Includes RFC-1006 Support)

5 TPDUs Used by RFC-1006

107751 Tandem Computers Incorporated 5–1

This section describes the TPDUs that are used by RFC-1006. Table 5-1 lists the six

TPDUs used by OSI/TS when using RFC-1006.

Table 5-1. TPDUs Used by RFC-1006

TPDU Function

CC-TPDU During connection establishment, used to confirm a CR-TPDU and to exchange user

data

CR-TPDU During connection establishment, used to request a transport connection and to

exchange user data

DR-TPDU During connection release, used to request a connection release

DT-TPDU During data transfer, used to transfer user data

ED-TPDU * During data transfer, used to transfer expedited user data

ER-TPDU Used to convey error information

*Normally the ED-TPDU is not provided for OSI transport protocol class 0, but it is included when

using RFC-1006.

The following TPDUs are not used by OSI/TS when using RFC-1006:

AK-TPDU

EA-TPDU

RJ-TPDU

DC-TPDU

Note RFC983 is an earlier version of a protocol for connecting ISO transport services on top of the TCP, and it

was superseded by the RFC1006 standard.

If you are connecting to a system that has implemented RFC983, there are differences in the transport

services between RFC983 and RFC-1006 that may have to be resolved before connections can be

successfully made.

For example, in RFC983, under Item 6, Packet Format, ER-TPDUs are not supported and the source and

destination reference bits in the CR- and CC-TPDUs are either set to 0 or ignored, but the Tandem

implementation of RFC-1006 uses ER-TPDUs, and puts information in the source and destination

reference bits.