Chapter 2 - Installing and Configuring the X.25 Option
This chapter explains how to install and configure the X.25 option.
If you ordered X.25 with your server, the required hardware and software is installed in the server already. Skip to the section "Assigning a Line at the Server Console" to set up the option.
If you ordered X.25 separately, the hardware and software that the option requires must be installed before you continue, as described in the next section.
Configuring the X.25 option consists of performing the following tasks:
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Assigning a Line at the Server Console ![]()
Defining connections using SVCs and PVCs ![]()
Managing connection information
To use the X.25 option, your server must have one ICA, ICAplus, or ICAmC card installed.
If you have not installed an ICA card, add an ICA card to the server. To do so, determine how adding X.25 affects the card' s performance. Use one or two ports for X.25 communications. Configure the card, then add it to the server. For instructions, see the ICA Installation Guide.
If you are using an ICA card, connect the modem or 7500 Data Module directly to the ICA port you want to use for X.25 communications.
If you purchased the X.25 option after you purchased your server, you must install the X.25 Option Key. To install the X.25 Option Key, follow these steps:
1. Make sure the Server Key is in place on a parallel port. Insert the X.25 Option Key into the Server Key.
2. From the Operator Menu, select Shut Down Server Software.
3. From the Shutdown Menu, select Shut Down Services and Return Console to Operator Menu.
4. From the Operator Menu, select System Maintenance.
5. Select Manage Software Options.
6. Select the function, Install Option Key Contents. When the operation is complete, you see the Manage Software Options screen. All the options on the server are displayed, including the X.25 option.
7. Return to the Operator Menu and select Restart Services.
8. Remove the Option Key from the Server Key, taking precautions against static electricity. The Option Key now has the status, USED.
If you disconnected a printer cable from the Server Key, reconnect it.
Store the Option Key in a secure place because you may need to use the key if you move the option to another server later.
Assigning a Line at the Server Console
After you connect a line to the serial communications card, you must specify certain information at the server console to enable the line. You must also provide parameters that you obtained from the PDN or the telephone company providing the ISDN service. Refer to your worksheets (PVC and SVC) in Chapter 1.
Note that PVCs through a PDN or ISDN network activate automatically when you assign the communications line. The connections to those sites are available without any intervention on your part.
To assign a line, follow these steps:
1. From the Operator Menu, select the Manage Communications function.
2. From the next menu, select Serial Communications.
3. Select the function, Manage Lines.
4. Select the function, X.25 Server-to-Server.
The system prompts you for the information in the next section.
System Prompts
When prompted, fill in the following information:
Slot Number. Enter the number of the slot that the card occupies.
Line Number. Enter the number of the line on the ICA card.
Line Speed. Enter the speed at which your modem or Data Module operates.
Is This a Leased (Dedicated) Line (Y/N)? Enter Y if the line is leased or N if the line is switched.
Is This Line Connected to a Public Data Network? Enter Y if you are using a PDN or ISDN network or assigning a switched or dedicated line to a host computer. The system displays the Select PDN/PTT menu. Skip to that paragraph below.
Enter N if you are not using a PDN. The system displays the prompt, "Will this server act as a DTE?" Enter Y if you want the server to act as DTE. Be sure to designate the server at the other end of the line as DCE. To designate a server as a DCE, enter N. Either server can have either designation, but you must have one DCE and one DTE. If the line is used for X.29 dial-in sessions, the server should be DCE. No further prompts appear.
Select PDN/PTT Menu. If the line is connected to a PDN, select the number of the PDN/PTT that you use. Some PDNs use the same name so check the country field to ensure that you select the correct one.
For X.29 dial-in sessions select the CCITT 84 Generic PDN.
Local DTE Address. Some PDNs or ISDN providers require the DTE address of the server that attempts to make the connection. You must enter the DTE address if the server supports X.29 dial-in sessions. If so, enter the DTE address here. If not, just press ENTER.
Number of Permanent Virtual Circuits (PVCs). Enter the number of permanent virtual circuits for which you contracted. If you enter zero, the system displays the prompt, "Number of Incoming Virtual Circuits (IVCs)." Skip to that paragraph below.
Starting PVC Number. The PDN assigns PVC logical channel numbers sequentially. The range of starting channel numbers (from 1 to 4095) tells the ICA card which circuits are PVCs. Enter the starting number here.
PVC Receive Packet Size. For each PVC, enter the size of the received data packets as agreed upon with your PDN/PTT at subscription time.
PVC Transmit Packet Size. For each PVC, enter the size of the transmitted data packets as agreed upon with your PDN at subscription time.
PVC Receive Window Size. For each PVC, enter the size of the receive window as agreed upon with your PDN/PTT at subscription time.
PVC Transmit Window Size. For each PVC, enter the size of the transmit window as agreed upon with your PDN/PTT at subscription time.
Number of Incoming Virtual Circuits (IVCs). Enter the number of virtual circuits for which you contracted. If you enter zero, the system displays the prompt, "Number of Two-way Circuits (TVCs)." Skip to that paragraph below.
Starting IVC Number. IVC logical channel numbers are assigned sequentially by the PDN or ISDN service provider. The range of starting channel numbers (from 1 to 4095) tells the ICA card which circuits are IVCs. This range cannot overlap the PVC range you specified earlier. Enter the starting number here.
Number of Two-way Virtual Circuits (TVCs). Enter the number of two-way virtual circuits for which you contracted. If you enter zero, the system displays the prompt, "Number of Outgoing Circuits (OVCs)." Skip to that paragraph below.
Starting TVC Number. Two-way virtual circuit logical channel numbers are assigned sequentially by the PDN or ISDN service provider. The range of starting channel numbers (from 1 to 4095) tells the ICA card which circuits are TVCs. This range cannot overlap the PVC/IVC ranges you specified earlier. Enter the starting number here.
Number of Outgoing Virtual Circuits (OVCs). Enter the number of outgoing virtual circuits for which you contracted. If you enter zero, the system displays the prompt, "SVC receive packet size." If any incoming or outgoing SVCs were specified earlier, skip to that paragraph below. If no SVCs were specified earlier, the system displays the prompt, "Facilities for this line." Skip to that paragraph.
Starting OVC Number. The PDN assigns OVC logical channel numbers sequentially. The number of channels added to the starting number (from 1 to 4095) tells the ICA card which circuits are IVCs. This range cannot overlap the PVC/IVC/TVC ranges that you specified earlier. Enter the starting number here.
Switched Virtual Circuits (SVCs) Receive Packet Size. Enter the size of received data packets on all SVCs as agreed upon with your PDN or ISDN service provider at subscription time.
SVCs Transmit Packet Size. Enter the transmit window size for all SVCs, as agreed upon with your PDN at subscription time.
Window Size. This value applies to all types of SVCs. It indicates the maximum number of packets transmitted or received without receiving an acknowledgment. You select a valid window size for all PDNs or ISDN networks specified. The window size is usually 2, but can be from 1 to 7. If a PDN supports only one window size, that size is used and you are not prompted for information.
Facilities for This Line. Your PDN or gives you any necessary facilities strings to request special services when a connection is made. Answer Y here if you want to provide facilities information. Then enter the appropriate values in hexadecimal two-character strings from 00 to FF. Enter N if you don' t want the option. Remember that facilities do not apply to X.29 dial-in sessions.
Caution: Enter the facilities carefully. If you make a mistake or enter a facility that is invalid for a specific PDN, all the calls made on that line fail.
Link Level Window Size. Enter the link level window size as agreed upon with your PDN at subscription time.
After you complete the above steps, the line is assigned for X.25.
Example Managing Serial Lines
In the following example, 16 two-way virtual circuits are configured on line 6, which is connected to the Telenet PDN.
If you do not use a PDN or ISDN network and the line between the two sites is leased, the two servers or the server and the host are connected as soon as you assign the line. If you use a PDN, all PVCs you defined are activated automatically. You shut down the line to deactivate these PVCs.
For switched lines to host computers, the server and the host computer are connected as soon as you dial the host. For X.29 dial-in sessions, the connection is made as soon as a workstation calls the server. For switched lines to other servers, treat the connection as an SVC. See the later section "Adding Connections to Remote Sites with SVCs." These sections also explain how to use the X.25 option for PDN connections that use SVCs.
When a connection between two servers is in effect, the two servers and any devices connected to them become one VINES network, subject to internetwork settings and access lists defined at each site. Depending on how these controlling elements are set up, users at one site may use services at the other site, and the servers may attempt to exchange Network Mail messages. For more information, see Managing VINES Security.
Adding Connections to Remote Sites with SVCs
This section describes how to add connections to remote servers through a PDN using SVCs.
You can use an SVC to connect any two sites, as long as both servers meet the hardware, software, line configuration, and PDN subscription requirements. You can schedule connections to take place at predetermined times or simply set up connections and use them as needed.
To add a remote server connection using SVCs, follow these steps:
1. From the Operator Menu, select the Manage Communications function.
2. Select Serial Communications.
3. Select the function, Manage Remote Site Connections.
4. Select the function, Add a Remote Site Name.
5. Select X.25 to describe how the remote site is connected to this server.
System Prompts
The system then prompts you for the following information:
Site Name. Enter a name to identify the remote site. The name does not have to match any StreetTalkTM name or any other data you enter. Choose a name that is easy to remember.
Slot Number. Enter the number of a slot that contains a serial communications card used for the X.25 option.
Line Number. For an ICA card, enter the number of the line or port on the serial communications card that connects this server to the remote site. This line must be assigned to X.25 and have the appropriate SVCs.
DTE Address. Enter the DTE address of the remote site provided by the PDN. To make the connection, the serial card uses one of the SVCs in the range you provided when you configured the line. Treat a switched non-PDN connection as a PDN and enter an address.
Accept Reverse Charges. Enter Y if you want this site to accept the charges for incoming connections from other sites. (Remember that answering Y uses up one virtual circuit.) Normally, incoming connections with reverse charging specified in the facilities field are rejected.
Facilities. Your PDN provides you with any necessary facilities strings to request special services when a connection is made.
Answer Y if you want to provide facilities information.
Enter the appropriate values, in hexadecimal two-character strings from 00 through FF.
Schedule. If you want connections made on a regular basis, enter a weekly schedule to connect to the remote site. Specify:
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The days of the week that connections should be made. ![]()
The time that the connection should be initiated. Specify the time using a 24-hour clock (for example, 14:30). ![]()
The duration of the connection in hours and minutes.
You can also configure the automatic reconnection of a transient link to remote X.25 sites if the connection is lost. See the section "Reconnecting an X.25 Transient Link" later in this chapter.
You can omit the scheduling information and make unscheduled connections from the server console. You can also initiate a connection that has a schedule by following the same procedure for initiating a connection that has no schedule. The next section explains this process.
Example Serial Communications
The following example shows the prompts displayed when a connection is added to a remote site.
If you schedule connections when you define remote sites, the connections are made automatically. This process makes the most sense if you have a private line to a PDN since a physical connection is always available. If your connection to the PDN or directly to the other server is through a switched telephone line, you must dial the proper number before attempting to make the connection.
Procedure
To make an unscheduled connection between two servers, follow these steps:
1. From the Operator Menu, select the Manage Communications function.
2. Select Serial Communications.
3. Select the function, Manage Remote Site Connections.
4. Select the function, Connect to a Remote Site.
5. Select the number that corresponds to the Site Name to which you want to connect.
If you make an unscheduled connection to a site that has a schedule and you later want to disconnect the two servers, you must do it manually. See the section "Disconnecting from a Remote Site" later in this chapter.
Note that a connection may fail if the PDN is overloaded or if all of the SVCs are in use.
Reconnecting an X.25 Transient Link
You can configure the automatic reconnection of a transient link to remote X.25 sites if the connection is lost for any reason.
To use this feature, follow the instructions in the "Procedures" section earlier in this chapter. When you set up a schedule, the system prompts you to answer the following:
Do you wish the connection re-established automatically if lost?
If you answer N, the system does not try to re-establish the connection.
If you answer Y, the system checks the connection at 5-minute intervals. If the connection was lost and the connection should be in progress according to the connection schedule, the system tries to re-establish the connection. Note that the system does not try to re-establish the connection if it closed during an idle period.
Disconnecting from a Remote Site
You can disconnect two servers at any time at the server console, whether or not the connection was initiated by a schedule. However, if automatic reconnection was configured, the connection is re-established if you disconnect it.
Procedure
To disconnect two servers, follow these steps:
1. From the Operator Menu, select the Manage Communications function.
2. Select Serial Communications.
3. Select the function, Manage Remote Site Connections.
4. Select the function, Disconnect from Remote Site.
5. Select the number that corresponds to the site from which you want to disconnect.
If your connection to the PDN is through a switched telephone line, you must also hang up the line.
If you want to disconnect an incoming call from another server, you need the local session number of the X.25 virtual circuit. If your server runs VINES Network and Systems Management (VNSM) software, you can use VNSM to find out the local session number.
With the local session number, you can clear the SVC for use by other incoming calls.
Finding the Local Session Number
To discover the local session number, follow these steps:
1. Enter the MNET command.
2. Select the server that uses the line you want to clear.
3. Select the function, DISPLAY Neighbors.
4. Look at the server names on the screen. The X.25 virtual circuit number appears above the line that displays the remote server' s name. Find the X.25 virtual circuit you want to clear and record its number.
5. Press ESC until you return to the Operator Menu.
Example Neighbors Screen
In the sample Neighbors screen, the local session number appears on the Neighbors screen next to the entry that reads "X.25 VC" and on the same line that displays the name of the remote server. Remote server BEBRUE001 has a local session number of 05 and server CAWN005 has 06 as its local session number. For details on Network Management, see Monitoring and Optimizing Servers.
Clearing the Circuit
To clear an X.25 virtual circuit, follow these steps:
1. From the Operator Menu, select the Manage Communications function.
2. Select Serial Communications.
3. Select Manage Lines.
4. Select Clear X.25 Virtual Circuit.
5. Enter the local session number of the virtual circuit that you want to clear.
When the virtual circuit clears, the system returns you to the Manage Serial Lines menu.
Managing Connection Information
This section explains how to manage information on remote connections. You also use the information in this section to manage a switched line connection that does not use a PDN.
Displaying Connection Information
Follow these steps to display, delete, and change the information associated with each SVC connection you have defined:
1. From the Operator Menu, select the Manage Communications function.
2. Select Serial Communications.
3. Select the function, Manage Remote Site Connections.
4. Select the function, Display Remote Sites.
The system displays the names of all connections you defined with an identifier for those that use X.25, and provides details about each connection (channel information, schedule, and so on).
Deleting a Connection
You can delete a connection at any time. Follow these steps:
1. From the Operator Menu, select the Manage Communications function.
2. Select Serial Communications.
3. Select the function, Manage Remote Site Connections.
4. Select the function, Remove a Remote Site Name. The system displays the names of all defined connections with an identifier for those that use X.25.
5. Select the number that corresponds to the connection you want to delete. All of the associated information is erased. You now re-use the site name if desired.
Changing Connection Information
To change the schedule or other connection information, first delete the connection, then add it with the new information. Follow the steps in the corresponding sections earlier in the chapter.