User`s guide

2: ADCCP NRM Protocol Summary
DC 900-1317J 35
between the primary function in one combined station and the secondary function in
the other. Each dialog uses its own separate address.
Theoretically, more than one pair of combined stations may be multiplexed on a single
physical link, so long as the assigned addresses and the hardware prevent contention for
transmission on the link.
2.5 Virtual Links and Multiplexing
Each physical link supports multiple virtual links. In unbalanced configurations, com-
munication between each secondary station and its primary station must be established
separately. In balanced configurations, if more than one pair of combined stations is
configured on the same physical link, each pair must establish communication inde-
pendently. Each of these configurations requires a separate mode setting command
frame (SNRM, SARM, SABM, SNRME, SARME, or SABME) and unnumbered
acknowledgment response frame (UA) for each virtual connection to be established on
the link.
The existence of multiple virtual connections on a single physical link requires that the
transmission of frames on the link be multiplexed. That is, control and information
exchange on one virtual connection must not interfere with that on another virtual
connection.
Unbalanced configurations that operate in normal response mode handle multiplexing
by defining an information exchange procedure that eliminates contention on the link.
Unbalanced configurations operating in asynchronous response mode require special
hardware (and/or software) to prevent contention on the link.
Balanced configurations normally involve only two combined stations operating on a
full duplex circuit. If more than one pair of combined stations operates on the same
physical link, special hardware (and/or software) is required to prevent contention on
the link.