OSI/AS Configuration and Management Manual

Installing and Configuring the Subsystem
OSI/AS Configuration and Management Manual—424119-001
4-6
X25AM Considerations
circuit first must be established. If you are having problems establishing the Network
Layer connection, check your NSAP ENTRY addresses and your profile or service
requirements. See Section 8, Troubleshooting Guide, for a more detailed discussion on
problem solving.
Naming X25AM Subdevices
When interfacing with X25AM, the TSP process builds an X25AM subdevice name by
using the first four characters after the $ character (the dollar sign) of its own TSP
process name as the prefix, followed by a three-character alphanumeric string. This
method allows for easy identification and prevents possible duplicate names created by
other TSP processes.
If more than one TSP process is using the same X25AM line across an Expand network,
the first four characters of all the TSP process names after the dollar sign ($) must be
unique across that network. Two TSP processes having the same first four characters
after the $ character in their process names can potentially cause problems—the two
processes may build similar subdevice names, based on their similar process names. In
such a case, one process, while trying to add an X25AM subdevice, may abort a
subdevice being used by the other process.
Creating X25AM Subdevices: Connect Requests
When a connect request is received, the TSP process determines whether to create a new
X25AM subdevice or to use an existing subdevice, based on the following criteria:
•
Configured transport class protocol
•
Value of the X25PVC attribute
•
Values of the MULTIPLEX and X25NCONMULTIPLEX attributes
•
Presence of existing but unused network connections (a possibility that is dependent
on the X25DISCONNECTDELAY attribute)
Creating X25AM Subdevices: Attach Requests
If multiplexing is not possible or the PASSIVEMUX attribute is set to OFF, then each
time a TSP process receives an attach request, it adds a new X25AM subdevice and
posts a network attach request to that subdevice.
When a TSP process receives an incoming CR-TPDU from the X25AM subsystem, it
establishes a network connection that is used for either one of the following:
•
The TSP subdevice for which the new X25AM subdevice was originally intended
•
Some other TSP subdevice in the connection-establishment phase
The TSP process determines, based on the configured local TSEL and the called TSEL
of the incoming CR-TPDU, whether to swap the linkage to the network connection
between the current TSP subdevice and the other newly established TSP subdevice. If
the remote system uses an existing network connection to establish a new transport
connection (multiplexing), then the unused X25AM subdevice is deleted.