Chapter 5. Configuring X.25 Options

SX.25 offers several options that may be added to the basic X.25 connection service. Some options affect the SX.25 application globally; these options are accessed from the Edit menu on the primary window. Other options pertain only to the individual ports where they are configured; these options are accessed from the Options menu and the Run Time Stacks menu on the WAN and LAN port configuration windows.

This chapter describes the configuration options that SX.25 offers and explains how to configure them:


Note: To make the procedures in this chapter take effect, you must stop and restart the network on the SX.25 host. For this reason, you might want to delay the network restart sequence until you have configured all the options that you plan to use.


The IP/IXE Option

Use the IP/IXE option to connect a port on the SX.25 host to an IP network. To support an IP connection, the IXE driver, which is the interface between the X.25 and the IP network, needs information about the IP network and the associated X.25 subnetworks (see “IP Network Connections” in Chapter 1 for more information). You provide this information by specifying parameter settings in the IP/IXE configuration window (shown in Figure 5-1).

Consider implementing the IXE map in conjunction with the IP network connection service. The IXE map enables hostnames to be entered in network transactions instead of addresses (see “The IXE Map Option” for instructions).


Note: If you are implementing IP on an unconfigured WAN port, you must rebuild the IRIX kernel to put the port into operation. Otherwise, you must stop and restart the network to put the new IP connection into effect.

Click these topics to view more information about using the IP/IXE option:

IP/IXE Configuration Procedure

Follow this procedure to configure a port for an IP network connection:

  1. Complete the “Port Selection Procedure” in Chapter 4.

    When you complete the port selection procedure, the WAN or LAN port configuration window is displayed (see Figure 4-7 or Figure 4-10).


    Note: If this is an unconfigured WAN port, complete the instructions in “Setting WAN Port Kernel Parameters” in Chapter 4 before going on to step 2, below.


  2. Specify the basic connection parameters for the port that you selected.

    If this is port is already configured, go directly to step 3 of this procedure. If this is an unconfigured port, complete steps 2 through 8 of “Creating a WAN Port Configuration Record” in Chapter 4 or steps 2 through 8 of “LAN Port Configuration Procedure” in Chapter 4 to configure the port. When you complete the instructions in Chapter 4, return to step 3, below.

  3. Select the ``IP/IXE'' option from the Options menu of the port configuration window.

    After your selection, the IP/IXE Configuration parameters window is displayed:

    Figure 5-1. IP/IXE Configuration Parameters


  4. Specify IXE driver information in the IP/IXE configuration window.

    Refer to the information in “IP/IXE Parameters” for an explanation of the IXE parameters that must be specified. When you complete the IXE specifications, click OK on the IP/IXE configuration window to confirm your IXE entries. The IP/IXE configuration window closes after your confirmation.

  5. Click OK on the port configuration window to confirm this port configuration.

    Clicking OK confirms the parameter settings for the basic connection service and for the IP/IXE function on this port. These settings are recorded in the SX.25 configuration file when you save it (step 6, which follows).

  6. Save your selections in the configuration file.

    Use the ``Save'' option from the File menu to save your configuration selections in the /etc/config/snetd.options file. If you opened a new file in step 1 of this procedure, use the ``Save As'' option instead. (See “Using the File Menu” in Chapter 3 if you need instructions for saving files.)

The IP option is configured on this port. It will go into effect the next time you restart the network (see “The Network Option” in Chapter 3 for instructions). However, if you have configured IP on a previously unconfigured WAN port, you must rebuild the IRIX kernel to put the new port into operation (see “Procedure to Rebuild the IRIX Kernel” in Chapter 4 for instructions).

IP/IXE Parameters

Use this information to determine how to set IP/IXE parameters in the IP/IXE configuration window:

IP Address 

Specifies the Internet address of the network to which this port will connect. Use dotted notation in your entry. The address for a new network should not duplicate an address that is already in use. (See Appendix A for address formatting information.)

IP Mask 

Specifies the subnet mask for this network, which designates the network portion of the Internet address. Use dotted notation in your entry.

For example, the mask 255.254.0.0 shows that the network portion of the address is 15 bits long and the host portion is the remaining 17 bits. The default subnetwork mask is 255.0.0.0.

Forward Broadcast Packets 


Specifies whether broadcast packets are received or rejected at this port; a check marks indicates that broadcast packets will be received.

NSDU High Water Mark 


Specifies the length at which a data packet, marked with the “More Data” mark (M-bit), is concatenated into a single network service data unit (NSDU). Override concatenation by specifying a maximum length. When the maximum is exceeded, concatenation stops and currently held data is passed to the Network Service user (with the More parameter set). Increase this value if you want IP to send or receive packets of over 576 octets, the default value.

Maximum Idle Time 


Specifies the time, in tenths of a second, that a connection on this network can remain idle before being closed. A timer is configurable for each X.25 network. When this timer expires, if there is no data on a connection, the virtual circuit to that network is closed. If data arrives from IP after the circuit is closed, the circuit is reopened. The default is 30.

Minimum Connection Time 


Specifies, in seconds, the minimum time that a connection must remain open before it can be preempted by another connection. If all X.25 circuits that are available to IXE are in use when an IP packet arrives for transmission to a new destination, one of the existing connections is closed. The connection that was idle for the longest time is selected for closing. The default value is 20.

X.25 mode 

Specifies whether the network operates in X.25(80), X.25(84), or X.25(88) mode.

CCITT/DDN Mode 


Specifies whether the network uses CCITT or DDN X.25. This is the way in which IP addresses are mapped onto X.25 addresses, as described in “IP Network Connections” in Chapter 1.

Reset Action 

Specifies how to handle reset requests. Select ACK to acknowledge the reset and discard it. Select DISC to disconnect the connection in response to reset requests.

Expedited Data Action 


Specifies how to handle expedited data requests. Select one:

ACK - acknowledge the expedited data but discard it.
DISC - disconnect the connection in response to expedited data.
RESET - reset the connection in response to expedited data (no reset).

PVC Channel Range 


Specifies how to handle the logical channels on this port that are allocated to PVCs. Select Ignore PVC Range Values to ignore all logical channels allocated to PVCs; or specify Low PVC Value and High PVC Value, in hexadecimal numbers, to include these PVC channels in the IXE configuration.

Low and high PVC comprise three hexadecimal digits and must be separated by a dash (“-”). For example, “009-00b” allocates three IXE PVC channels.

Listen Information 


Sets the application to listen for incoming calls with the specified CUD fields and called addresses. There are two possible formats:

CUD field, called addresses field; 
I|S bytes | X , I|S D|N semi-octets | X;

The fields in the previous address format signify:

I means “match this field identically”
S means “match this field starting with”
X means “ignore this field”
D means “this field refers to an X.25 DTE”
N means “this field refers to an X.25 NSAP”

This is the last IXE parameter. Return to step 5 of “IP/IXE Configuration Procedure” to complete the IXE configuration process.

Removing the IP/IXE Service From a Port

To remove the IP/IXE service from a port, display the IP/IXE parameters window (shown in Figure 5-1; see steps 1 through 3 of “The IP/IXE Option” for details). Click Clear on the IP/IXE parameters window to remove all IP/IXE information for the port.

To put your changes into effect, stop and restart the network (see “The Network Option” in Chapter 3 for more information).

The PVC Map Option

Use the PVC Map option to configure a port to operate with permanent virtual circuits. Because the default settings in SX.25 parameter files do not provide for PVCs, you must first create a custom X.25 parameter file that specifies the logical channel ranges for the PVCs. After you create this file, you can configure the remaining PVC parameters, shown in Figure 5-2, and use the customized file to store your settings.


Note: If you are implementing PVCs on an unconfigured WAN port, you must rebuild the IRIX kernel to put the port into operation. Otherwise, you must stop and restart the network to put new PVCs into effect.

Click these topics to view more information about using the PVC Map option:

PVC Configuration Procedure

Use this procedure to create an X.25 parameter file and configure PVCs.

  1. Perform the “Port Selection Procedure” in Chapter 4 to select the port for the PVCs.

    After your selection, the WAN or LAN configuration window is displayed (see Figure 4-7 or Figure 4-10).


    Note: If this is an unconfigured WAN port, complete the instructions in “Setting WAN Port Kernel Parameters” in Chapter 4 before going on to step 2, below.


  2. Specify the subnet ID and DTE address if the port is unconfigured.

    If this is a configured port, the subnet ID and DTE address are automatically displayed on the WAN or LAN configuration window, and you can go directly to step 3. If this is an unconfigured port, these fields are empty; enter the subnet ID and DTE address of the port where the PVCs will operate; then go on to step 3.

  3. Open an X.25 parameter file to use as a template.

    You cannot modify a factory-shipped X.25 parameter file, but you can open an existing file, specify changes, and save the file under a different name. To open a file, select the X.25 parameter file that is most appropriate for the port where the PVCs will operate; then, click the Open button to display the contents of the file.

  4. Select the Logical Channels tab and reset the PVC channel range.

    Selecting the Logical Channels tab displays the list of logical channel parameters and their settings (see Figure 7-3). By default, Low PVC Channel and High PVC Channel are set to zero. Refer to the information following Figure 7-3 or use the values recommended by your service provider to reset these values.

  5. Click the Save As button to record your changes.

    The Save As button (shown in Figure 7-1) prompts you to assign the new X.25 parameter file a name. Enter the new filename in the dialog box and click the OK button.

    Notice that the new file is listed in the X.25 Parameter Files list.

  6. Assign the new X.25 parameter file to this port.

    Select the new X.25 parameter file and click the Assign button (shown in Figure 4-7 and Figure 4-10) to designate it as the packet-level parameter file to be used on this port.

  7. Select ``PVC Map'' from the Options menu to configure the remaining parameters.

    After your selection, the PVC Map is displayed (shown in Figure 5-2).

    Figure 5-2. PVC Map Parameters


  8. Allocate the logical channels for this port.

    To allocate a channel for a PVC, select it and modify the packet-size and window-size parameters according to the specifications of your network service provider; then, click the Allocate button. When you finish the channel allocations, click the Close button to close and save the PVC map and return to the port configuration window.

  9. Specify the link procedure for this port.

    Refer to step 6 of “Creating a WAN Port Configuration Record” or the step 6 of “LAN Port Configuration Procedure” if you need more information on this step.

  10. Specify the LAPB (for WANs) or LLC2 (for LANs) parameter file for this port.

    Refer to step 8 of “Creating a WAN Port Configuration Record” or the step 8 of “LAN Port Configuration Procedure” if you need more information on this step.

  11. Click OK to confirm your settings.

    After your entry, the WAN or LAN port configuration screen closes; however, the PVC configuration is not recorded until you explicitly save it to a configuration file (step 12, which follows).

  12. Save the PVC configuration in an SX.25 configuration file.

    To save the PVC information in an SX.25 configuration file, use the ``Save'' option from the File menu on the Primary Window; use the ``Save As'' option from the File menu if you opened a new file in step 2 of “Port Selection Procedure”. (See “Using the File Menu” in Chapter 3 if you need instructions for saving files.)

This port is configured for PVCs. It will go into effect the next time that you restart the network (see “The Network Option” in Chapter 3 for instructions). However, if you configured PVCs on a previously unconfigured port, you must rebuild the IRIX kernel to put the new port into effect (see “Procedure to Rebuild the IRIX Kernel” in Chapter 4 for instructions).

Removing a Permanent Virtual Circuit

To remove a PVC from a port, display the PVC map for the port (shown in Figure 5-2; see steps 1 through 7 of “The PVC Map Option” for details). Then, select the PVC that you want to remove and click the Free button. Notice that the PVC is now designated free on the PVC map.

To put your changes into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).

Run Time Parameters Option

A run-time stack provides a means to operate a port using alternate protocol parameters to test or tune port operation. The port can remain in operation while you configure and test its run-time parameters. If you wish, you can save the run-time parameters in a file and use them as the permanent configuration settings for the port.

Use this procedure to set run-time parameters on a configured port:

  1. Complete the “Port Selection Procedure” in Chapter 4.

    Open the configuration file that contains the port's configuration information (normally /etc/config/snetd.options); then, select the port from the list of configured ports. The WAN or LAN port configuration window is displayed after your selection (see Figure 4-7 or Figure 4-10).

  2. Select a stack from the Run Time Parameters menu.

    The Run Time Stacks menu contains two options: ``X.25'' and ``LAPB.'' Select ``X.25'' to reset packet-level parameters or ``LAPB'' to reset link-level parameters for run-time operation.

    If you select ``X.25,'' the X.25 General Parameters window is displayed (see Figure 7-2). If you select ``LAPB,'' the LAPB General Parameters window is displayed (see Figure 7-14). The parameter settings that you see in the general parameter window are the settings that the port is currently using: settings from the parameter file that were applied to the port during the previous port configuration session, or settings that were most recently assigned as run-time parameters.

  3. Set the new run-time parameters for the port.

    Adjust the port parameters that require changes. If you need more information, see “Creating an X.25 Parameter File” in Chapter 7 for resetting packet-level parameters and “Creating a LAPB Parameter File” in Chapter 7 for resetting link-level parameters.

  4. Click OK to put the run-time parameters into effect.

    The new parameters that you set take effect as soon as you click OK.

  5. Save the run time parameters in a file (optional).

    If you decide that you want to save these parameters in a file, click the Save As button; then, enter the name of the new file in the filename dialog box. If you decide to use the new parameters permanently, reconfigure the port and apply the new parameter files in the port configuration procedure (described in the “WAN Port Configuration Procedure” and the “LAN Port Configuration Procedure” in Chapter 4).

The IXE Map Option

Use the IXE map to enable users to designate IP network hosts by their hostname instead of their address. This map contains the IP address or hostname of each IP network node to which the SX.25 host will connect. Hostname entries in the IXE map must appear in the /etc/hosts file of the SX.25 host. The IXE Map Configuration window, shown in Figure 5-3, allows you to add, delete, and change IP host entries.


Note: You must stop and restart the network to put a new IXE map into effect.

Click these topics to view more information about using the IXE Map option:

IXE Map Configuration Procedure

To create the IXE map, follow this procedure:

  1. Select the ``IXE Map'' option from the Edit menu.

    After your selection, the IXE Map Configuration window is displayed:

    Figure 5-3. IXE Map of IP Hosts


  2. Click the Add button on the IXE map configuration window.

    Clicking the Add button displays the IP/IXE map record, shown in Figure 5-4.

    Figure 5-4. IP/IXE Map Record


  3. Complete a map record for each IP network to which this SX.25 host connects.

    Each record associates a port with an IP network by associating the port DTE address with the IP address of the remote node. The record also specifies the window and packet size for data exchanges over the connection. Refer to “IP/IXE Map Parameters” to enter your specifications for each record.

  4. When a record is complete, click OK to record your specifications.

  5. Close and save the IXE map.

    When the IXE map contains a record for each IP host, click the Close button on the IXE Map Configuration window (see Figure 5-3) to close and save the map.

To put the new IP/IXE map into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).

IP/IXE Map Parameters

Use this information to determine how to set IP/IXE map parameters:

  1. IP Address/Host Name 


    Specifies the Internet address of the reciprocating host on the IP network. You can use the IP hostname instead of its address if the IP node is listed in the SX.25 /etc/hosts file. See “IP Network Connections” in Chapter 1 for information on address formats.

    X.25 Address 

    Specifies the DTE address of the port that supports the connection to the IP network. The DTE address is specified in the port configuration procedure (see Figure 4-7 and Figure 4-10).

    Packet Size 

    Specifies the maximum packet size of incoming and outgoing datagrams; fragmentation takes place if a packet exceeds the maximum packet size configured for the port (default packet size is 576 octets). Use the Packet Size option menu to select a packet size.

    Window Size 

    Specifies the maximum window size for incoming and outgoing data. The valid range is 0 through 127.

Changing the IXE Map

To remove a record from the IXE Map, select an entry on the map and click the Delete button (see Figure 5-3). To modify information in an IXE map record, select an entry and click the Edit button. Clicking the Edit button displays the record for the selected entry and allows you to change it. Click OK to record your changes; then, click Close on the IXE Map Configuration window to save the IXE map.


Note: To put your changes into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).


The PAD Map Option

The PAD map allows users to designate X.25 network hosts by their hostname instead of their address. This map contains the name, address, and call information for each X.25 network host reciprocating in PAD connections. The address and call information is automatically supplied in user connection requests. Hostnames can be associated with aliases. The PAD map configuration window (shown in Figure 5-5) allows you to add, delete, and change X.25 host entries. The record that you create for a PAD host comprises several screens.


Note: You must stop and restart the network to put a new PAD map into effect.

Click these topics to view more information about using the IP/IXE option:

PAD Map Configuration Procedure

To create a PAD map, follow this procedure:

  1. Select the ``PAD Map'' option from the Edit menu on the primary window.

    After your entry, the PAD Map Configuration window is displayed:

    Figure 5-5. PAD Map Configuration Window


  2. Click the New button on the PAD Map Configuration window.

    Clicking the New button displays the first field of the PAD map record, shown in Figure 5-6. Each record identifies a reciprocating X.25 host and defines its services.

  3. Complete a PAD map record for each X.25 network host to which users will connect.

    A complete PAD map record comprises four groups of parameters, which are shown in Figure 5-6 through Figure 5-9. Refer to the parameter descriptions that follow each figure to enter your specifications for each record.

  4. When a record is complete, click OK to record your specifications.

  5. Close and save the PAD map.

    When the PAD map contains a record for each X.25 host, click the Close button on the PAD Map Configuration window (see Figure 5-5) to close and save the map.

The new PAD map is ready to use. To put it into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).

General Parameters of the PAD Map

The General tab is illustrated in Figure 5-6; its parameters are described in the information that follows the figure.

Figure 5-6. General Parameters in a PAD Map Record


Host Name 

Specifies the name of the X.25 host reciprocating in the connection.

X.25 Address 

Specifies the X.25 address of the reciprocating host. An X.25 address comprises four fields (refer to the x25addr(5) reference page or “X.121 Addresses” in Appendix A). The field entries should be separated by a dot. Only the first field is mandatory for a WAN address. Two fields are mandatory for a LAN address. Trailing dots may be omitted. This is a valid X.25 address:

A.234231500010.N.38826110002345678941

X.29 Type 

Specifies the X.29 protocol to be used in connections. Accept the default or use the option menu beside the X.29 Type field to reset it to 1980, 1984, or 1988. The default is the value set in the X.25 parameter file.

Call User Data 

Specifies the Call User Data string that is sent in a call request. It may be of any length up to 124 ASCII characters. If you enter more than 12 characters, fast select is automatically used.

Facilities Parameters of the PAD Map

The Facilities tab is illustrated in Figure 5-7; its parameters are described in the information that follows the figure.

Figure 5-7. Facilities Parameters in a PAD Map Record


Incoming and Outgoing Packet Size 


Specifies the incoming and outgoing packet sizes. The range for the parameter is 16 to 4096 bytes.

Incoming and Outgoing Window Size 


Specifies the values of the incoming and outgoing window sizes. The range for the window size is 1 through 127.

Fast Select 

Specifies whether fast select is in effect (check mark indicates that fast select is active).

Reverse Call Charges 


Specifies whether reverse call charges is in effect (check mark indicates that reverse call charges is active).

CUG and RPOA Parameters of the PAD Map

The closed user group (CUG) and recognized private operating agency (RPOA) tab is illustrated in Figure 5-8; its parameters are described in the information that follows the figure.

Figure 5-8. CUG and RPOA Parameters in a PAD Map Record


CUG Settings 

Specifies the user group class. Select Multi-user or Bilateral.

CUG Number 

Specifies that the call is to be made to the specified Closed User Group on the specified host. Enter the CUG number (up to four digits).

RPOA Settings 

Specifies additional routing information about calls to this host to transit networks. Enter up to four RPOA numbers; each entry consists of four digits.

Aliases Parameters of the PAD Map

The Aliases tab is illustrated in Figure 5-9. An alias is any alternative hostname that a user might enter in connection requests to the host.

Figure 5-9. Alias Parameters on a PAD Map Record


Changing the PAD Map

To remove a record from the PAD Map, select an entry on the map and click the Delete button (see Figure 5-5). To modify information in a PAD map record, select an entry on the map and click the Edit button. Clicking the Edit button displays the record for the selected entry and allows you to change it. Click OK to record your changes; then, click Close on the PAD Map Configuration window to save the PAD map.

To put your changes into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).

The PADD Listen Strings Option

PADD listen strings specify the called addresses and CUD field values for which the SX.25 application is prepared to accept calls. The PADD Listen String Configuration window is shown in Figure 5-10.


Note: If you add, delete, or modify a listen string, you must stop and restart the network to put your changes into effect.

Click these topics to view more information about PADD listen strings:

Listen Strings Configuration Procedure

To add PADD listen strings, follow this procedure:

  1. Select the PADD option from the Options menu on the primary window.

    After your selection, the PADD Listen String Parameters window is displayed:

    Figure 5-10. PADD Listen String Parameters


  2. Enter the string in the Listen String field.

    See “PADD Listen String Formats,” which follows, for information on entering listen strings.

  3. Click Add to add your entry to the Listen String list.

  4. Repeat steps 1 and 2 for each listen string you want to add.

  5. Click Close when the list is complete to save the Listen Strings list.

The listen string list is ready to use. To put it into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).

PADD Listen String Formats

Listen strings restrict the hosts that are allowed to access PAD services on this host. The strings have two formats:

CUD field, called addresses field; 
I|S bytes | X , I|S D|N semi-octets | X; 

The fields in the previous address format signify:

I means “match this field identically”
S means “match this field starting with”
X means “ignore this field”
D means “this field refers to an X.25 DTE”
N means “this field refers to an X.25 NSAP”

For example, suppose the CUD field starts with 01000000; the address field starts with 2342 and contains an X.25 DTE address. The following listen string would be entered:

S01000000,SD2342; 

Changing and Removing PADD Listen Strings

To change a PADD listen string, display the PADD Listen String Parameters window (shown in Figure 5-10), select the listen string that you want to change, and click Clear. Enter the new listen string and click Add to add it to the Listen String list. When your changes are complete, click Close to save the modified Listen String list.

To remove a PADD listen string, display the PADD Listen String Parameters window, select the listen string that you want to remove, and click Delete to remove it from the Listen String list.

To put your changes into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).

The Subnetwork Names Option

As a convenience to users, you can assign names to WAN and LAN subnetworks so that users can enter a name to designate a subnetwork instead of its address. The Subnetworks Configuration window (shown in Figure 5-11) allows you to create the records that associate subnetwork addresses with their name and description.


Note: After you configure subnetwork IDs, you must stop and restart the network to put your changes into effect.

Click these topics to view more information about the using subnetwork names:

Subnetwork Names Configuration Procedure

To configure subnetwork names, follow this procedure:

  1. Select the ``Subnetworks'' option from the Edit menu on the primary window.

    After your selection, the Subnetworks Configuration window is displayed:

    Figure 5-11. Subnetworks Configuration Window


  2. Enter the name, address, and description of the subnetwork.

    The subnetwork name is a name that is easily identified by users on the SX.25 host; the X.25 address is the DTE address that you assigned in the port configuration procedure (see Figure 4-7 and Figure 4-10) and the description field is any information about the subnetwork that helps to identify it.

  3. Click the Add button to enter the subnetwork on the Subnetwork Names list.

  4. Complete a record for each subnetwork that you want to make available by name.

  5. When all subnetwork names are entered, click Close to save the Subnetwork Names list.

The subnetwork names list is ready to use. To put the list into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).

Changing the Subnetwork Names List

To change a subnetwork record, select the subnetwork in the Subnetwork Names field and click Clear; then enter the new record for the subnetwork. To remove a subnetwork record, select the subnetwork in the Subnetwork Names list and click Delete (removing a subnetwork record does not remove the port from service; it simply makes it unavailable by its subnetwork name). After you make your changes, click Close to save the modified subnetwork names list.

To put your changes into effect, stop and restart the network (see “The Network Option” in Chapter 3 for instructions).