Note: The information contained in this article is structured as help information for the System Management Interface Tool (SMIT) and is not intended for general reading.
Using SMIT, you can view the values set for the X.25 adapter attributes and compare them with the details of your network subscription. Then, if necessary, you can change the attribute values to suit your requirements.
Once you have completed the initial configuration, all of the network attributes have default values. However, these may not be suitable for your requirements. You should specify the details for each type of virtual circuit, according to your network subscription.
Check your network subscription to ensure that you have the correct values specified for the packet attributes. These include default and maximum-negotiable values for throughput class, packet size, and window size for SVCs; optional facilities; ISO 8208-defined timers; and other packet-level features.
Some of these values, such as default packet size and D-bit, can be overridden for an individual SVC call in the call-request packet.
The defaults for the frame attributes have been set up so that they will satisfy the needs of most networks. You should change their values only if you are sure they need changing and you understand X.25 packet-level and frame-level protocols.
In most circumstances, you should not need to change any of the general attributes. If you are using SNA Services over X.25, however, you will need to change the receive data transfer offset attribute.
If you intend to use permanent virtual circuits (PVCs), you should use SMIT to check the default values for the PVC attributes. If these default values are not suitable for your PVCs, you can change them. Consult your network subscription for details. These default values will then be used by all PVCs, unless you override the values in individual PVC definitions.
If one or more of your PVCs has requirements that differ from the default values, you can create a definition for an individual PVC, specifying the logical channel number to be used for it. You can override the values specified for the default PVC. Consult your network subscription for details.
Indicates the network you intend to use. The value can be
Indicates the network user address (NUA) of the local data terminal equipment (DTE). Do not include any subaddress (suffix). The value must be 1 through 15 decimal digits.
Indicates the lowest-numbered logical channel that can be used for an incoming switched virtual circuit (SVC). The number depends on your network subscription and must be in the range 0 through 4095. The default is
Indicates the maximum number of logical channels that can be used for incoming switched virtual circuits (SVCs). The number depends on your network subscription and must be in the range 0 through 64. The default is
Indicates the lowest-numbered logical channel that can be used for a two-way switched virtual circuit (SVC). The number depends on your network subscription and must be in the range 0 through 4095. The default is
Indicates the maximum number of logical channels that can be used for two-way switched virtual circuits (SVCs). The number depends on your network subscription and must be in the range 0 through 64. The default is
Indicates the lowest-numbered logical channel that can be used for an outgoing switched virtual circuit (SVC). The number depends on your network subscription and must be in the range 0 through 4095. The default is
Indicates the maximum number of logical channels that can be used for outgoing switched virtual circuits (SVCs). The number depends on your network subscription and must be in the range
Indicates the lowest-numbered logical channel that can be configured as a permanent virtual circuit (PVC). The number depends on your network subscription and must be in the range 0 through 4095. The default is
Indicates the maximum number of permanent virtual circuits (PVCs) for which the link can be configured. The number depends on your network subscription and must be in the range
Indicates the support provided for an auto-call unit. The value must be
Indicates which version of X.25 should be supported. The value must be
Indicates the modulo to be used for packet transmission. The value must be 8 or 128. The default value is
Indicates whether the adapter is to be configured as a data circuit-terminating equipment (DCE) or a data terminal equipment (DTE). The value must be
Indicates the default receive packet size, in bytes, that will be received. This can be altered for an individual call, using the optional facilities in the call-request packet. The size must be one of the following values:
Indicates the default transmit packet size, in bytes, that will be sent. This can be altered for an individual call, using the optional facilities in the call-request packet. The size must be one of the following values:
Indicates the default receive packet window (the number of packets allowed to be received without confirmation). The number must be in the range 1 through 127. The default is
Indicates the default transmit packet window (the number of packets allowed to be sent without confirmation). The number must be in the range 1 through 127. The default is
Indicates the default receive throughput class for non-negotiating calls. The class must be one of the following values:
Indicates the default transmit throughput class for non-negotiating calls. The class must be one of the following values:
Indicates the maximum receive packet size, in bytes, that can be agreed upon through negotiation, for packets received on the link. The size must be one of the following values:
Indicates the maximum transmit packet size, in bytes, that can be agreed upon through negotiation, for packets sent on the link. The size must be one of the following values:
Indicates the negotiated maximum receive packet window size (the number of packets allowed to be received without confirmation). The number must be in the range 1 through 127. The default is
Indicates the negotiated maximum transmit packet window size (the number of packets allowed to be sent without confirmation). The number must be in the range 1 through 127. The default is
Indicates the maximum receive throughput class that can be achieved through negotiation. The class must be one of the following values:
Indicates the maximum transmit throughput class that can be achieved through negotiation. The class must be one of the following values:
This is an optional facility available on some X.25 networks that conform to 1980 or 1984 standards. If your network supports this facility and you have subscribed to the facility, select
This is an optional facility available on some X.25 networks that conform to 1984 standards. If your network supports this facility and you have subscribed to the facility, select
Indicates the time (in seconds) within which a call-connected, clear-indication, or incoming-call packet should be received following a call-request packet being transmitted. The value must be in the range 1 through 255. The default is
Indicates the time (in seconds) within which a reset-confirmation packet should be received following a reset-request packet being transmitted. The value must be in the range 1 through 255. The default is
Indicates the time (in seconds) within which a clear-confirmation packet should be received following a clear-request packet being transmitted. The value must be in the range 1 through 255. The default is
Indicates the time (in seconds) within which an RR packet should be sent following a packet carrying an acknowledgment being transmitted. The value must be either 0 (meaning T24 is disabled) or in the range 1 through 255. The default is
Indicates the time (in seconds) within which, if no acknowledgment has been received, a packet is retransmitted. This is the packet equivalent of the T1 timer. The value must be either 0 (meaning T25 is disabled) or in the range 1 through 255. The default is
Indicates the time (in seconds) within which an interrupt-confirmation packet should be received following an interrupt packet. After this time, the virtual circuit is reset. The value must be either 0 (meaning T26 is disabled) or in the range 1 through 255. The default is
Indicates whether the throughput class is negotiated or validated. Validate means that, instead of throughput class being negotiated, the incoming throughput class value will be checked for acceptability; if unacceptable, the call will be cleared. The value must be
Indicates whether the packet size is negotiated or validated. Validate means that, instead of packet size being negotiated, the incoming packet size value will be checked for acceptability; if unacceptable, the call will be cleared. The value must be
Indicates whether incoming calls are allowed. If incoming calls are not allowed, they are cleared immediately. The value must be
Indicates whether outgoing calls are allowed. If outgoing calls are not allowed, they are cleared immediately, returning a clear-indication packet to the user. The value must be
Indicates whether fast-select calls are allowed. The value must be
Indicates whether the use of the D-bit in the call-request packet is allowed. The value must be
Indicates how many reset packets can be sent consecutively before the virtual circuit is considered to have failed. The value must be in the range 0 through 127. The default is
Indicates how many clear packets can be sent consecutively before the switched virtual circuit is considered to have failed. The value must be in the range 0 through 127. The default is
Indicates the parameter settings for a closed user group (CUG). One of the CUGs can be a preferential (default) CUG). A preferential CUG is not specified in the facilities of the call. The value must be one of the following. The default is
Indicates whether a bilateral closed user group is set up. The value must be either
Indicates whether incoming reverse charge calls are allowed. The value must be either
Indicates whether outgoing calls can be paid for locally. The value must be either
Indicates the window size to use at the frame level. This is the allowable number of frames to be sent or received before waiting for an acknowledgment. If the frame modulo is set to
Indicates the time (in units of 50 milliseconds) after which, if it has not been acknowledged, a frame is retransmitted. This is the CCITT T1 value. The value must be in the range 1 through 255. The default is
Indicates the time (in seconds) after which, if there has been no activity on a link, an RR frame is sent. Frame-level recovery is started if no answer is received within T1. The value must be either 0 (meaning T4 is disabled) or in the range 4 through 255. The default is
Indicates the maximum number of times a frame can be transmitted under error conditions. This is the CCITT N2 value. The value must be in the range 1 through 255. The default is
Indicates the connection mode. In passive connection mode, X.25 waits for an SABM from the network to determine whether the network is connected. In active connection mode, X.25 sends SABMs to the network, waiting for the network to send a UA to acknowledge that it is connected. The value must be
When connecting to the network terminating unit (NTU), DTR is raised and the lines DCD and DSR are tested. These lines becoming active indicates that the network terminating unit is ready. After raising DTR, these lines are tested at intervals and this value gives the number of tests after which the attempted connection is considered to have failed. The value must be in the range 1 through 255. The default is
Indicates the time (in units of 50 milliseconds) that elapses between each poll of the physical level. The value must be in the range 10 through 255. (10 represents 0.5 second. The default is
Once the physical connection is established, a constant check is made on it. The intervals are controlled by this attribute. If the value is 0, any detection of DCD being inactive immediately causes the physical layer to be brought down. For other values, DCD and DSR are tested and must be inactive for this many tests, for the physical layer to be brought down. The value must be in the range 0 through 255. The default is
Indicates the numbering modulo used by the frame level. This is used to order the frames within the frame window. The value must be
Indicates the receive data transfer offset to be used by SNA Services. Do not set this value to anything other than 0 unless you are using SNA. The value must be in the range 0 through 1024. The default is
Indicates the maximum number of bytes of data that will be traced on the line. The value must be in the range 1 through 65535. The default is
Indicates whether line monitoring system (LMS) should control the flow of traffic through the X.25 port when there is a shortage of trace buffers. The value must be
Indicates whether the X.25 adapter should allow addresses in the call- accept and call-request packets. The value must be either
Indicates the number of seconds that will elapse between the last call being cleared and the line being disconnected. This only applies if an auto-call unit is attached. The value must be in the range 0 through 1800. (0 means that the line will stay connected, even when there are no calls in progress.The default is
Identifies the PVC being defined. The numbers are from 1 through n, where n is the number of PVCs subscribed to (up to a maximum of 64). (This is not shown on the dialog for defining a default PVC.)
Indicates the logical channel number of the PVC. The value must be in the range of logical channel numbers supplied by the network provider.
Indicates the maximum receive packet size, in bytes, that will be received on permanent virtual circuits. The size must be one of the following values:
Indicates the transmit packet size, in bytes, that will be sent on permanent virtual circuits. The size must be one of the following values:
Indicates the maximum receive packet window (the number of packets allowed to be received without confirmation) on this PVC. The number must be in the range 1 through 127. The default is
Indicates the maximum transmit packet window (the number of packets allowed to be sent without confirmation) on this PVC. The number must be in the range 1 through 127. The default is
Indicates whether the use of the D-bit is allowed on this PVC. The value must be
Indicates the value to be sent in a reset packet at startup of the PVC. A value of
Each X.25 adapter installed is defined to the operating system as a device in the /dev directory. Each X.25 adapter has one X.25 port that, in turn, enables one X.25 link to be established from the adapter to an X.25 network. Each port may be connected to a different network. The link referred to in the X.25 application programming interface (API) corresponds exactly to the X.25 port. Multiple virtual circuits can be established on one link.
Use SMIT to list the adapters installed on your system. SMIT gives a list of the names given to the adapters by the installation process and tells which slot each adapter is in. Use the adapter name as the port name when using the X.25 commands such as xtalk, xmanage and xroute.
Configure the X.25 Co-Processor/2 or Multiport/2 adapter.
If you intend to use SNA Services over an X.25 network, you also need to:
-Define X.25 attachment characteristics.
-Define QLLC (X.25) logical link characteristics.
-Define QLLC (X.25) physical link characteristics.
If you intend to use TCP/IP over an X.25 network, you need to configure the network interface.
The RCM installation process adds a definition for the X.25 adapter. However, the adapter cannot be used for communications until you add the network user address (NUA) and the network identifier; this sets default values for several of the other X.25 adapter attributes. These default values are suitable for the network indicated by the country code part of the NUA and the network identifier.
When completed, the initial configuration gives a partially working, but not fully configured system. You may have to change some of the network attributes to values supplied by your network provider (particularly if the network cannot be identified from the NUA).