OSI/AS Configuration and Management Manual

Performance Considerations
OSI/AS Configuration and Management Manual—424119-001
6-6
MULTIPLEX Attribute
MULTIPLEX Attribute
The MULTIPLEX attribute allows multiple Transport Layer connections to use one
Network Layer connection. Multiplexing transport connections on a single line makes
more effective use of your network connections and reduces the overhead involved in
setting up a new connection. You should, however, look carefully at the amount of
traffic on the network connections. Too many transport connections multiplexed onto a
network connection can overload the network connection. This can cause excessive
queueing for use of the line, which degrades response time.
CONNECTTIMEOUT Attribute
The CONNECTTIMEOUT attribute defines the amount of time to wait for a response to
a CR-TPDU. If you set this value too high, transport connections could be delayed
because the connection is unnecessarily tied up during the timeout period. You should
try to specify a time interval long enough to allow the CR-TPDU and the CC-TPDU to
traverse the communications line in both directions. The interval should also be long
enough for the various OSI layers to process the data, including processing to set up the
connection acceptance.
DISCONNECTTIMEOUT Attribute
The DISCONNECTTIMEOUT attribute is similar to CONNECTTIMEOUT; it, too,
negatively affects throughput if the value is set too high. For OSI/AS, this attribute
defines the amount of time the session service provider waits for a T-DISCONNECT
indication after issuing a session release or abort service request. For OSI/TS, it defines
the amount of time TSP waits for a response to a DR-TPDU.
If this value is set too high in your OSI/AS subsystem, connections could be delayed by
being unnecessarily tied up during the connection release timeout period. If set too low,
a user issuing an abort request or a release response could be disconnected due to the
expiration of the timer instead of the agreement with the remote user. You should be
careful, however, to set the value high enough to allow processing of outstanding data
received before the disconnection is completed.
CLASS Attribute
The CLASS attribute specifies the transport class to be used on the connection. You
should select a transport class that matches the network type. For example, if the
network is extremely reliable, you probably do not need to specify class 4, which incurs
more overhead because of the error recovery procedures. (Of course, if you are using a
LAN, or you are using SNDCF or OSI IP over an X.25 network, you are required to
select class 4.)