OSI/TS Configuration and Management Manual

OSI Transport Services
OSI/TS Configuration and Management Manual—424831-001
5-13
Connection Multiplexing
Whether multiplexing is used or not depends on the following factors:
•
The negotiated class (multiplexing is not supported in classes 0 and 1)
•
The configured value of the MULTIPLEX parameter (default is OFF)
•
The configured value of X25NCONMULTIPLEX
•
Whether SETPARAM 13 has been issued to change the configured value of
MULTIPLEX
•
Whether the configured local and remote NSAPs are identical
•
Whether the configured X25DESTADDR and X25PORT are identical
If the negotiated class is 2, 3, or 4 and MULTIPLEX is ON, OSI/TS tries to map
outgoing connection requests onto existing network connections between the same
NSAP addresses. If NSAPs are not configured, OSI/TS looks for the DESTADDR and
the X25PORT values. Only the first X25AM subdevice is created and then shared by
subsequent outgoing connections.
Whether or not to multiplex is a decision made by the local initiating transport entity it
is not a negotiated parameter. OSI/TS multiplexes outgoing connections based on the
subdevice configuration, regardless of the configuration of the remote entity. Note that
the OSI/TS subsystem does not have control over multiplexing of incoming connections.
However, multiplexing of incoming connections can take place only if the transport
connections are going to have the same Network Layer address.
For X.25 networks, multiplexing is generally used to conserve resources (to reduce the
number of virtual circuits used). In configurations having transient transport
connections (in which the transport connections are established and destroyed quickly),
multiplexing can also be used to improve performance. Nonmultiplexed subdevices
incur more system overhead because they must establish a network connection before
each transport connection can occur. Multiplexed subdevices, however, need only
initiate the network connection once before establishing multiple transport connections.
Figure 5-3. Connection Multiplexing
Transport Connection
Network Connection
(X.25 Virtual Circuit)
Physical Connection
CDT503.CDD