[ Previous | Next | Contents | Search ]
AIXLink/X.25 1.1 for AIX: Guide and Reference

Configuration Structure

With multiport adapters , more than one X.25 port can be associated with a given adapter. When the Licensed Program is configured, X.25 ports are set up to use the available ports on a given communications adapter. Supported under AIX are the X.25 Interface Adapter and the ARTIC Portmaster Adapter, with its V.24, V.35 or X.21 interfaces. These adapters produce device instances of the form ampx and apm, respectively. When configuring the Licensed Program, the X.25 support can be added to any of the available adapters. If an adapter is to be used by the X.25 Licensed Program, then its device driver has to be associated with the adapter. Once a device driver is configured onto a given adapter, then as many ports as the adapter supports can be configured. The main device used is the X.25 port as shown in the following figure.

The device driver is associated with the adapter, and there can only be one available per adapter. The X.25 ports are associated with the individual communication ports supported by the adapter, which can vary from one up to eight. It is the individual X.25 ports that must be configured with their NUA, packet information, and so forth. For example, when the traffic on an X.25 line is traced, the port name, sx25a0 is passed to x25mon.

When each device is added to the systems configuration, be it a device driver or an X.25 port, it is given an instance number based on what is next available. This means the device driver's instance number might not match the adapter it is configured on. The relationship between what ports are configured on a given device driver or adapter can be viewed through smit or by entering the lsx25 command.

Once an X.25 port is available, it can be used by a number of possible applications:

Triple-X PAD

A PAD allows remotely attached ASCII terminals to access applications running in X.25 based hosts. Refer to "Packet Assembler/Disassembler (PAD) Overview" for more details.

The PAD support can be enabled or disabled for the system, refer to "Configuring X.25 Communications with SMIT" . If enabled, one instance of X.29 supports all the configured X.25 ports, servicing all remote terminals using the PAD. Where the system is being used as a terminal PAD, each terminal has its own X.3/X.28 session.


Each X.25 port can have COMIO emulation enabled. This emulation produces a programming interface compatible with that in the base AIX Version 3 X.25 support. Applications such as xtalk can use the emulation without recompiling. To allow for this emulation, a device entry is created with the same device name that would have been generated by the base AIX Version 3 X.25 support - /dev/x25s . Refer to "Configuring X.25 Communications with SMIT" for details on using this emulation.

AIX Base Version 3 X.25 users It is possible that these emulation ports are configured alongside the ports of the base X.25 support. Regardless of what X.25 support the instance uses, its number will be unique. Instances of the two types might be interspersed. Whether it is based on the X.25 Licensed Program support or not can be checked using ODM, SMIT, or the lsx25 command.

Not all applications supplied with Version 3 are supported. xmanage and xmonitor do not apply to the Licensed Program's emulation ports. x25mon can be used to trace the activity of the X.25 line.

                          Transmission Control Protocol/Internet Protocol (TCP/IP) support can be added to any of the X.25 ports. The system allows IP addresses to be matched to an NUA. If an IP connection is required to a given remote X.25 DTE, then a virtual circuit is acquired and the IP data is sent. A typical TCP/IP port would be xs0 . The instance number of the TCP/IP port is not necessarily the same as the X.25 port it is configured on. Refer to "Configuring X.25 Communications with SMIT" and to "Configuring TCP/IP" in the AIX Version 4.3 System Management Guide: Communications and Networks for details.
                          Network Provider Interface (NPI) provides a programming interface for the packet layer. Refer to "NPI Overview" for information on its use. Each instance of an NPI-based application accesses the NPI module as required. There are no separate configuration steps for NPI.
                          Data link provider interface (DLPI) provides a programming interface to the frame, LAP-B, layer. Refer to "DLPI Overview" for information on its use. Though the access is to LAP-B rather than X.25, an X.25 port must be configured and set up to allow use of the DLPI interface. When DLPI is enabled, X.25 access to the port is disabled. Refer to "General Parameters" details.

The following figure shows how driver instances relate.

Note: See "Appendix H. Using AIXLink/X.25 over the IBM 2-Port Multiprotocol Adapter" for information on differences when using 2-Port Multiprotocol Adapters.

[ Previous | Next | Contents | Search ]