TS Supplement (Includes RFC-1006 Support)

Changes in the Transport Layer When Using RFC-1006

Introduction to RFC-1006

107751 Tandem Computers Incorporated 1–17

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was superseded by the RFC1006 standard.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 places information in the source and destination

reference bits.

Encapsulation of TPDU Into

the Transport Packet

The OSI TPDU is encapsulated by OSI/TS into a transport packet as specified by the

RFC 1006 standard. This is shown in Figure 1-12.

Transport Packet Format

and Length

Data is transmitted from a transport service entity (through TCP/IP, over the network)

to the peer entity in a transport packet. A transport packet consists of two parts: 4

bytes of packet header to identify the RFC-1006 protocol, and the TPDU. Figure 1-12

illustrates the transport packet.

Figure 1-12. Transport Packet

Version Reserved Packet Length

Transport Packet Header

TPDU Header User Data

TPDU

Transport Packet

055

Octet 1 2 3 , 4 5-p