OSI/TS Configuration and Management Manual

OSI Transport Services

OSI/TS Configuration and Management Manual—424831-001

5-12

Multiplexing

Note that for the protocol classes that do not provide multiplexing (classes 0 and 1),

SRC-REF and DST-REF are not used that is, they do not appear in the DT-TPDU.

Multiplexing

The hierarchy of addresses described in the preceding subsection allows multiple

outgoing transport connections to share a single network connection, such as an X25AM

subdevice. This is called connection multiplexing and is valid only for connection-

oriented network service (WAN connections).

Passive multiplexing is a form of connection multiplexing used for incoming attach

requests. These are both discussed in more detail in the following subsections.

Connection Multiplexing

Connection multiplexing allows multiple transport connections to share a single X.25

virtual circuit if they have the same Network Layer address (the same NSAP or the same

DTE along with the port).

Figure 5-3

illustrates a possible OSI/TS configuration with three transport connections

multiplexed through a single address.

Figure 5-2. Relationship Between SRC-REF and DST-REF

502CDT .CDD

Initiating

Transport Entity

Responding

Transport Entity

CR-TPDU

SRC-REF

DST-REF

CC-TPDU

SRC-REF

DST-REF

DT-TPDU

DST-REF 46

DT-TPDU

12DST-REF