22 - Building SNA Server

• How to configure your SNA Server - Enhance your understanding of the SNA Server Admin program by learning about the Servers and Connections, LU Pools, and Users and Groups windows.

• How to configure connections between the SNA Server and the host computer - Learn what the common connection properties are and how to set them up.

• How to complete the detailed configuration of SDLC, 802.2, X.25, and Channel Attached connections - See the basic and advanced configuration dialog boxes for each of these connections and gain an understanding of what the different configuration parameters actually do.

After the initial installation of SNA Server, including the installation and setup of link services, has been successfully completed by using the SNA Server Setup program, you must use the SNA Server Admin program to build the SNA Server. This initial build process requires you to configure the server and the SNA Server-to-host connections. Then you must implement the SNA Server (make it operational) by performing procedures covered in Chapter 23, "Implementing SNA Server."

This chapter examines the concepts and procedures for configuring the SNA Server and also for configuring the SNA Server-to-host connections.

Configuring Your SNA Server

• The Servers and Connections window, which is used to configure servers, connections, and LUs; start and stop servers and connections; and reset LUs

• The LU Pools window, which is used to configure LU pools

• The Users and Groups window, which is used to assign properties, LUs, and LU pools for users

Fig. 22.1 - The SNA Server Admin display contains the Servers and Connections, LU Pools, and Users and Groups windows.

Perform the following steps to configure your SNA Server:

1. In the Servers and Connections window, click any item to make the Servers and Connections window the active window on the SNA Server Admin screen. Then select the SNA Server to be configured.

2. In the SNA Server Admin menu, choose Services, Properties. The Server Properties dialog box appears (see fig. 22.2).

   Fig. 22.2 - The Server Properties dialog box is used to define the basic parameters for the SNA Server.

3. In the Comment box, enter any comment you would like to assign to the server. Comments can be up to 25 characters long. You may want to enter a comment, for example, that describes the role of the server (primary, backup, and so on), or you may desire to leave this box blank. Entries in this box are optional.

4. In the SNA Network Control Point Name area, enter the local Network Name and Control Point Name if required. Generally, if the SNA Server will be accepting incoming calls that use Format 3 Exchange Identifiers (XIDs) (the default type of incoming call identifiers), or if it is to be used for 6.2 type LUs, you should specify both the local Network Name and the Control Point Name. These two names work together to identify this local server node to the other network resources. For this reason, if either of the names is supplied, the other name should also be supplied. The SNA host system administrator should advise you as to whether these two names are required, and if so, what the names should be.

   
   When you are connecting to a host system and you are using a local Network Name, the local Network Name must match the NETID parameter in the VTAM Start command for the local VTAM system, and the local Control Point Name must match the CPNAME parameter in the PU definition for the host. In such cases, the local Network Name and local Control Point Name should be supplied by the SNA host system administrator.
   

5. When used, each name can contain up to eight alphanumeric characters (including the special characters @, #, and $). Lowercase letters are automatically converted to uppercase.

   If this SNA Server is going to connect to an AS/400 host, use the Control Point Name of the SNA Server for the Network Name.

6. Click OK.

Configuring SNA Server-to-Host Connections

Assigning New Connections to the SNA Server

1. In the Servers and Connections window, click any item to make the Servers and Connections window the active window on the SNA Server Admin screen. Then select the server to which the new connection is being assigned.

2. In the SNA Server Admin menu, choose Services, New Connection to display the Insert Connection dialog box shown in figure 22.3.

   Fig. 22.3 - The standard Insert Connection dialog box with the default channel type selected.

3. In the Connection area of the dialog box, select the type of connection being assigned by clicking the appropriate radio button.

4. Click OK to close the Insert Connection dialog box and display the Connection Properties dialog box for the connection type specified. Figure 22.4 portrays the Connection Properties dialog box for an 802.2 connection.

Fig. 22.4 - The Connection Properties dialog box for an 802.2 connection.

Configuring Common Connection Properties

The following steps detail the procedure for configuring the properties common to all the different connection types:

The first step is really a continuation of the procedure described earlier for assigning a new connection to the SNA Server. The last step of that procedure caused the Connection Properties dialog box (for the connection type assigned) to be displayed.

1. In the Connection Name box, enter a unique name for this connection. The name has a maximum length of eight alphanumeric or special (@, #, and $) characters and cannot be the reserved name SNASERVR.

2. In the Comment box, enter any comment up to 25 characters. Entries in this box are optional.

3. In the Link Service box, click the drop-down list box and select the desired link service from the list. Remember the link service allows this connection to access your installed communications adapter. If the link service you need is not listed, you must cancel this part of the configuration and go back to install the link service using the SNA Server Setup program.

4. If this connection is of the X.25 type, the Connection Properties dialog box contains a Virtual Circuit Type option. Either accept the default selection (Switched), or override the default by making your own selection. Switched virtual circuits (SVCs) are dynamically called and cleared, and the destination address is supplied when the circuit is called. On the other hand, permanent virtual circuits (PVCs) are constantly active, and the destination address is preset.

5. In the Remote End area of the Connection Properties dialog box, select the remote system type for this particular connection. If this is a "direct-connect" connection (Channel type, Twinax type, or DFT type), the correct remote end is automatically selected. The available types are as follows:
   • Host System. This is usually a mainframe system that controls interactions to the devices connected to it. If this connection will be using dependent Advanced Program-to-Program Communication (APPC), select this type of remote system. Also select this type of remote system if this connection will be used for 3270 or LUA LUs.

   • Peer System. This can be any size computer system that communicates with another computer system on an equal basis, and each computer system shares communications control. Do not select this type of remote system if the connection will be using dependent APPC.

   • Downstream. This can be any client system that accesses host connections available on the SNA Server directly instead of using the SNA Server client/server interface.

   
   Because this connection is being used for communications between the SNA Server and the SNA host (a host or peer system), do not select the Downstream option. Downstream connections (connections between the SNA Server and special kinds of remote systems) are discussed later in this chapter.
   

6. The Activation setting applies only to outgoing calls. Therefore, if the Allowed Directions setting (described in step 7) includes outgoing calls, a default option will be highlighted. You can accept the default option or override it by making your own selection. If the connection is configured to accept incoming calls, the connection starts listening for calls whenever the SNA Server is started. The options for the Activation setting are as follows:
   • On Server Startup. This is the default option for 802.2 and DFT connections. When this option is selected, the connection is started whenever the SNA Server used by this connection is started. This option results in faster access time for the first user who connects after SNA Server startup and is the best choice when communications line charges are fixed regardless of time used rather than assessed for only the time used. Therefore, this option is best for X.25 permanent virtual circuit connections, SDLC leased-line connections, and 802.2 connections.

   • On Demand. This is the default option for all connection types except 802.2 and DFT connections. When this option is selected, the connection is started when the user tries to activate an LU session on the connection and stopped when the session is completed. The cost benefits of this option are obvious as line charges are assessed only for the time used. This option would be best suited for SDLC switch-line connections and X.25 switched virtual circuit connections.

   • By Administrator. When this option is selected, the administrator must control the connection activation on a case-by-case basis.

7. In the Allowed Directions area of the Connection Properties dialog box, select the appropriate call directions, outgoing, incoming, or both. The default selection is the Outgoing Calls option. For an SDLC type downstream connection, Outgoing Calls must be selected. For Channel, Twinax, and DFT connections, the call direction is preselected.

8. Click Setup to configure basic and advanced properties for SDLC, 802.2, X.25, and Channel Attached connections; or click OK to accept these initial configuration settings and exit the dialog box. Because DFT and Twinax connections only require the settings in the Connection Properties dialog box, their configurations are completed by also clicking OK.

Completing Configuration of SDLC Connections

The first step is really a continuation of the procedure described earlier for configuring common connection properties. The last step of that procedure is repeated in the first step here for continuity.

1. Click Setup in the Connection Properties dialog box to display the SDLC Setup dialog box, shown in figure 22.5.

   Fig. 22.5 - This SDLC Setup dialog box is used to define the basic configuration parameters for an SDLC connection.

2. In the Dial Data box, enter the telephone number (up to 40 characters) of the modem to be called. If your modem is attached to an SDLC adapter with a built-in COM port, it probably is capable of accepting a phone number from the SNA Server. In this case, enter the phone number that the SNA Server should send to your modem. Be sure to use the format expected by your modem. If your modem only accepts manually dialed numbers, then enter the phone number as it should appear in the pop-up message when the SDLC connection is started.

   
   The Dial Data box in the SDLC Setup Dialog box is available only if the SDLC connection is using a switched line. Because leased SDLC lines are essentially point-to-point lines not requiring a phone number to establish the distant-end modem connection, this Dial Data box is not available for SDLC connections using leased lines.
   

3. In the Local Node Name area, enter the Local Node ID, an eight-digit hexadecimal value that uniquely identifies the local SNA Server to the remote host, peer, or downstream system. After the first three digits (the block number) of the Local Node ID are typed, the cursor positions itself in the second half of the Local Node ID box so that the remaining five digits (the node number) can be entered. Be sure that you use the same Local Node ID for all the connections and link services on this SNA Server. The default Local Node ID value is 05D FFFFF. The block number portion of the Local Node ID cannot be 000 or FFF, and the node number portion cannot be 00000, as these values are reserved.

   
   Coordinate the Local Node ID value with the remote system administrator so that corresponding VTAM parameters in the host system can be set up to match the Local Node ID. For host systems, the block number should match the IDBLK variable, and the node number should match the IDNUM variable in the VTAM PU definition.
   

4. In the Remote Node Name area, enter the Network Name and Control Point Name if they are required. The Network Name identifies the remote system's SNA network and is required if you will be using Format 3 XIDs. Likewise, the Control Point Name identifies the remote system on the SNA network and is required if Format 3 XIDs will be used. These two names work together to identify this system to the other network resources. For this reason, if either of the names is supplied, the other name should also be supplied. The SNA host system administrator should advise you as to whether these two names are required, and if so, what the names should be.

   
   When you are connecting to a host system and you are using a remote Network Name, the name must match the NETID parameter in the VTAM Start command for the remote VTAM system. The remote Control Point Name must also match the SSCPNAME parameter in the VTAM Start command for the remote VTAM system. In such cases, the remote Network Name and remote Control Point Name should be supplied by the remote system administrator.
   

5. When used, each name can contain up to eight alphanumeric characters (including the special characters @, #, and $). Lowercase letters are automatically converted to uppercase.

   If this connection will access an AS/400 host, use the network name of the AS/400 in the Network Name box and the AS/400 name in the Control Point Name box.

6. Also in the Remote Node Name area, enter the Remote Node ID, an eight-digit hexadecimal value that uniquely identifies the remote host, peer, or downstream system. The remote system administrator should provide the proper value to enter. After the first three digits (the block number) of the Remote Node ID are typed, the cursor positions itself in the second half of the Remote Node ID box so that the remaining five digits (the node number) can be entered. The block number portion of the Remote Node ID cannot be 000 or FFF, and the node number portion cannot be 00000, as these values are reserved.

7. If you want to change the connection activation limit defaults (also called retry timers), click Retry Timers in the SDLC Setup dialog box. The two activation limits available for modification are described in the following list:
   • Maximum Number of Attempts. This is the number of times the SNA Server should attempt to establish the connection with the host. When the specified number of unsuccessful attempts has been made, the SNA Server quits trying and makes the appropriate entries in the event log. Any number of attempts can be specified, from 1 through No Limit, with No Limit being the default.

   • Delay After Failed Attempts. This is the number of seconds the SNA Server should wait after each failed attempt before it tries once again to establish the connection. The permissible range for this timer limit is from 5 seconds to 255 seconds, with 10 seconds being the default.

8. SNA Server is designed to provide reasonable defaults for the advanced SDLC settings, and under normal circumstances, these defaults work fine. If you want to accept the basic settings just entered and use the SDLC default advanced settings as well, go to step 9. Otherwise continue with step 8.

9. If you need to view and/or modify these advanced SDLC default settings, click Advanced in the SDLC Setup dialog box to expand the SDLC Setup dialog box to include the advanced settings (see fig. 22.6). Each advanced SDLC configuration setting is described in the following list:

   Fig. 22.6 - When you click Advanced in the basic SDLC Setup dialog box, the dialog box expands to display the advanced configuration parameters for SDLC connections.

   • XID Type. Specify the type of identifying information the SNA Server should send. Two formats (types) can be selected: Format 0 and Format 3. When Format 0 XIDs are used, only the Node ID is sent. This type should only be used for hosts that do not support Format 3 XIDs, which send up to 100 bytes of identification information, including the Local Node ID and Control Point Name. If independent APPC LUs are going to be used on this connection, Format 3 XIDs must be specified. Format 3 is also the default XID type.

   • Encoding. Specify the encoding scheme your modem should use for this connection. Both the local and remote modems should use the same encoding scheme. Also, when multiple SDLC connections using the same link service will be accepting incoming calls, the encoding scheme for all the connections must match. The two possible schemes are Nonreturn to zero (NRZ) and Nonreturn to zero inverted (NRZI). Contact your host system administrator to determine the NRZI setting in the LINE/GROUP definition in VTAM. Your modem's encoding scheme must match this setting. If VTAM does not specify a setting, use the standard default setting of NRZI.

   • Duplex. Select the setting appropriate for your modem. If you did not set the Constant RTS option for any of your adapters during installation using the SNA Server Setup program, then only the default setting of half-duplex (Half) is available. Otherwise, both half-duplex and full-duplex (Full) are available.

     
     Because IBM SDLC and MPCA adapters cannot handle full-duplex transmission at high speeds due to the lack of a coprocessor, you should use the half-duplex setting when you want to use transmission speeds greater than 9600 baud.
     

   • Data Rate. Select the setting appropriate for your modem. The Low setting can be used to increase the reliability of transmissions over lines that are noisy and produce errors at higher rates of speed. The High setting gives faster transmissions and is the default setting.

     
     Errors occur at the High setting. Poor-quality lines may be the problem. Try transmitting with the Low setting selected to see if the errors disappear.
     

   • Poll Address. Either accept the C1 default value or enter a two-digit hexadecimal number that uniquely identifies this SNA Server connection to the remote system. If the remote system is an IBM host mainframe, contact the host system administrator for the ADDR parameter in the VTAM PU definition. The poll address and the ADDR parameter must match. If the remote system is a peer system, however, the poll address can be any value except those reserved for special use (00 and FF).

   • Poll Rate. Either accept the default value of 5 or enter a new value from 1 through 50 to represent the number of polls per second that should occur. Poll rate can only be specified if the remote system is a peer or downstream system. Otherwise, this box will be unavailable.

   • Poll Timeout. Either accept the default value of 10 or enter a new value from 1 through 300 to represent the length of time, in tenths of a second, the local system should wait for a poll response before polling the remote system again. Poll timeout is only applicable for sessions in which the SNA Server is functioning in the primary link role, and therefore, affects all downstream and some peer system sessions.

   • Poll Retry Limit. Either accept the default value of 10 or enter a new value from 1 through 255 to represent the number of times the local system should poll the remote system without getting a poll response. The poll retry limit is only applicable for sessions in which the SNA Server is functioning in the primary link role, and therefore, affects all downstream and some peer system sessions.

   • Contact Timeout. Either accept the default value of 10 or enter a new value from 5 through 300 to represent the length of time, in tenths of a second, the local system should wait after an unsuccessful connection attempt before trying to connect to the remote system again. Contact timeout is only applicable for outgoing calls and, therefore, is ignored for incoming calls.

   • Idle Timeout. Either accept the default value of 300 or enter a new value from 1 through 300 to represent the length of time, in tenths of a second, the local system should wait for a transmission response before trying again. The idle timeout is only applicable for sessions in which the SNA Server is functioning in a secondary link role, and therefore, affects all host mainframe and some peer system sessions.

   • Idle Retry Limit. Either accept the default value of 10 or enter a new value from 1 through 255 to represent the number of times the local system should attempt to transmit data to the remote system without getting a response. The idle retry limit is only applicable for sessions in which the SNA Server is functioning in a secondary link role, and therefore, affects all host mainframe and some peer system sessions.

   • Max BTU Length. Either accept the default value of 265 or enter a new value from 265 through 16393 to represent the maximum length of the basic transmission unit (BTU). A BTU, also known as an I-frame, is the number of bytes that can be transmitted in a single data-link control frame. If you are using a mainframe host connection, the Max BTU length should be equal to or less than the value specified for the MAXDATA parameter in the VTAM PU definition. If you are using a downstream connection, you should specify a Max BTU length equal to or less than the maximum supported value of the downstream system. Contact the host or downstream system administrator for the values to use.

   • Multidrop Primary. Click this check box to mark it (with an X) if you are using a leased line for the SDLC connection to a downstream system and the SNA Server will be functioning as a primary node communicating with multiple secondary nodes at the same time (using the same transmission mechanisms). Click the marked check box to unmark it (remove the X) when the SNA Server is not functioning in a multidrop capacity.

   • Select Standby. The default for this setting is off (the check box is empty, or unmarked). If your modem is capable of supporting a standby line and you want to activate that capability, simply click the Select Standby check box to mark it (with an X).

   • Switched Connection Establishment Timeout. Either accept the default value of 300 or enter a new value from 10 through 500 to represent the length of time, in seconds, the user or modem will have to actually dial the number of the remote system. This setting is only available when switched SDLC lines are used for outgoing calls. If manual dialing is required, allow sufficient time for the remote system to answer and establish the connection.

10. Click OK to accept the settings and exit the SDLC Setup dialog box, or click Cancel to exit the dialog box without accepting the settings.

Completing Configuration of 802.2 Connections

The first step is really a continuation of the procedure described earlier for configuring common connection properties. The last step of that procedure is repeated in the first step here for continuity.

1. Click Setup in the Connection Properties dialog box to display the 802.2 Setup dialog box, shown in figure 22.7.

   Fig. 22.7 - This 802.2 Setup dialog box is used to define the basic configuration parameters for an 802.2 connection.

2. In the Remote Network Address box, enter the 12-digit hexadecimal network address of the remote host, peer, or downstream system. This network address should be provided by the SNA host system administrator or network administrator. The standard default Remote Network Address is 400000000000.

3. In the Local Node Name area, enter the Local Node ID, an eight-digit hexadecimal value that uniquely identifies the local SNA Server to the remote host, peer, or downstream system. After the first three digits (the block number) of the Local Node ID are typed, the cursor positions itself in the second half of the Local Node ID box so that the remaining five digits (the node number) can be entered. Be sure that you use the same Local Node ID for all the connections and link services on this SNA Server. The default Local Node ID value is 05D FFFFF. The block number portion of the Local Node ID cannot be 000 or FFF, and the node number portion cannot be 00000, as these values are reserved.

   
   Coordinate the Local Node ID value with the remote system administrator so that corresponding VTAM parameters in the host system can be set up to match the Local Node ID.
   

4. In the Remote Node Name area, enter the Network Name and Control Point Name, if required. The Network Name identifies the remote system's SNA network and is required if you will be using Format 3 XIDs. Likewise, the Control Point Name identifies the remote system on the SNA network and is required if Format 3 XIDs will be used. These two names work together to identify this system to the other network resources. For this reason, if either of the names is supplied, the other name should also be supplied. The SNA host system administrator should advise you as to whether these two names are required, and if so, what the names should be.

   
   When you are connecting to a host system, and you are using a remote Network Name, the name must match the NETID parameter in the VTAM Start command for the remote VTAM system. Also, the remote Control Point Name must match the SSCPNAME parameter in the VTAM Start command for the remote VTAM system. In such cases, the remote Network Name and remote Control Point Name should be supplied by the remote system administrator.
   

   When used, each name can contain up to eight alphanumeric characters (including the special characters @, #, and $). Lowercase letters are automatically converted to uppercase.

   If this connection will access an AS/400 host, use the Network Name of the AS/400 in the Network Name box and the AS/400 name in the Control Point Name box.

5. Also in the Remote Node Name area, enter the Remote Node ID, an eight-digit hexadecimal value that uniquely identifies the remote host, peer, or downstream system. The remote system administrator should provide the proper value to enter. After the first three digits (the block number) of the Remote Node ID are typed, the cursor positions itself in the second half of the Remote Node ID box so that the remaining five digits (the node number) can be entered. The block number portion of the Remote Node ID cannot be 000 or FFF, and the node number portion cannot be 00000, as these values are reserved.

6. If you want to change the connection activation limit defaults (also called retry timers), click Retry Timers in the 802.2 Setup dialog box. The two activation limits available for modification are described as follows:
   • Maximum Number of Attempts. This is the number of times the SNA Server should attempt to establish the connection with the host. When the specified number of unsuccessful attempts has been made, the SNA Server quits trying and makes the appropriate entries in the event log. Any number of attempts can be specified, from 1 through No Limit, with No Limit being the default.

   • Delay After Failed Attempts. This is the number of seconds the SNA Server should wait after each failed attempt before it tries once again to establish the connection. The permissible range for this timer limit is from 5 seconds to 255 seconds, with 10 seconds being the default.

7. SNA Server is designed to provide reasonable defaults for the advanced 802.2 settings, and under normal circumstances, these defaults work fine. If you want to accept the basic settings just entered and use the 802.2 default advanced settings as well, go to step 9. Otherwise continue with step 8.

8. If you need to view and/or modify these advanced 802.2 default settings, click Advanced in the 802.2 Setup dialog box to expand the 802.2 Setup dialog box to include the advanced settings. The advanced 802.2 configuration setting are shown in figure 22.8 and described in the following list:

   Fig. 22.8 - When you click Advanced in the basic 802.2 Setup dialog box, the dialog box expands to display the advanced configuration parameters for 802.2 connections.

   • XID Type. Specify the type of identifying information the SNA Server should send. Two formats (types) can be selected: Format 0 and Format 3. When Format 0 XIDs are used, only the Node ID is sent. This type should only be used for hosts that do not support Format 3 XIDs, which send up to 100 bytes of identification information, including the Local Node ID and Control Point Name. If independent APPC LUs are going to be used on this connection, Format 3 XIDs must be specified. Format 3 is also the default XID type.

   • Remote SAP Address. Enter the remote system access point (SAP) address, or as recommended in most cases, accept the default of 04. SAP addresses must be two-digit hexadecimal numbers, evenly divisible by 4, in the hexadecimal range between 04 and EC. Coordinate with the remote system administrator to determine the proper Remote SAP Address value.

   • Retry Limit. Enter the number of times, from 0 to 255, the SNA Server should retransmit a frame without receiving a response from the remote host, peer, or downstream system. The default value is 10. If 0 is used for the retry limit, the SNA Server will use its internal default retry limit.

   • Max BTU Length. Enter the maximum length of the basic transmission unit (BTU), using values in the range from 265 to 16393. A BTU, also known as an I-frame, is the number of bytes that can be transmitted in a single data-link control frame (see fig. 22.9).

     Fig. 22.9 - Suggested Max BTU Lengths to use under the stated conditions.

   • XID Retries. Either accept the default value of 3 or enter a new value from 0 through 30 to represent the number of times the local system should retransmit an identifying message when the remote system is not responding.

   • Response (t1) Timeout. Enter the amount of time the local system should wait before attempting to retransmit to a nonresponding remote system. This setting has two default values. One is for a remote system on a local ring (default is expressed in milliseconds), and the other is for a remote system on a remote ring (default is expressed in seconds). These default values are 400 milliseconds and 2 seconds, respectively. If you choose to enter a specific timeout value rather than accepting the default values, the timer always waits the specified amount of time regardless of whether the remote system is on a local or a remote ring. Therefore, it is usually best to use the default values if they are sufficient.

   • Receive ACK (t2) Timeout. Enter the maximum amount of time the local system should wait before acknowledging receipt of a transmission. This setting should be less than the value used for the Response Timeout (t1) setting. Acknowledgments automatically are sent at the expiration of this timer unless some other condition has already prompted an acknowledgment. This setting has two default values. If the remote system is on a local ring, the default value is 80 milliseconds; and if the remote system is on a remote ring, the default value is 800 milliseconds. If you choose to enter a specific timeout value rather than accept these default values, the timer always waits the specified amount of time regardless of whether the remote system is on a local or a remote ring. Therefore, it is usually best to use the default values if they are sufficient.

   • Inactivity (ti) Timeout. Enter the maximum amount of time the local system should wait before shutting down an inactive link. This setting has two default values, depending on whether the remote system is on a local or remote ring. These default values are 5 seconds and 25 seconds, respectively. If you choose to enter a specific timeout value rather than accept these default values, the timer always waits the specified amount of time regardless of whether the remote system is on a local or remote ring. Therefore, it is usually best to use the default values if they are sufficient.

   • Receive ACK Threshold. Either accept the default value of 2 or enter a new value from 1 through 127 to represent the maximum number of frames the local system can receive before it is required to send a response to the remote system.

   • Unacknowledged Send Limit. Either accept the default value of 8 or enter a new value from 1 through 127 to represent the maximum number of frames the local system can send before it receives a response from the remote system.

9. Click OK to accept the settings and exit the 802.2 Setup dialog box, or click Cancel to exit the dialog box without accepting the settings.

Completing Configuration of X.25 Connections

The first step is really a continuation of the procedure described earlier for configuring common connection properties. The last step of that procedure is repeated in the first step here for continuity.

1. Click Setup in the Connection Properties dialog box to display the X.25 Setup dialog box reflected in figure 22.10.

   Fig. 22.10 - This X.25 Setup dialog box is used to define the basic configuration parameters for an X.25 connection.

2. In the Remote X.25 Address box, enter the 12-digit or 15-digit hexadecimal network address of the remote host, peer, or downstream system. If a 15-digit address is used, the last three digits are used for routing between host, peer, and downstream systems having the same 12-digit address. This network address should be provided by the SNA host system administrator or network administrator. If the host is a system using VTAM, this address value must also match the DIALNO parameter in the VTAM PORT definition.

3. In the Local Node Name area, enter the Local Node ID, an eight-digit hexadecimal value that uniquely identifies the local SNA Server to the remote host, peer, or downstream system. After the first three digits (the block number) of the Local Node ID are typed, the cursor positions itself in the second half of the Local Node ID box so that the remaining five digits (the node number) can be entered. Be sure that you use the same Local Node ID for all the connections and link services on this SNA Server. The default Local Node ID value of "05D FFFFF" can be used if the connection is using a permanent virtual circuit (PVC) because the destination address will be preset. The block number portion of the Local Node ID cannot be 000 or FFF, and the node number portion cannot be 00000, as these values are reserved.

   
   Coordinate the Local Node ID value with the remote system administrator so that corresponding VTAM parameters in the host system (if used) can be set up to match the Local Node ID. Ensure the block number matches the IDBLK parameter, and the node number matches the IDNUM parameter value in the VTAM PU definition.
   

4. In the Remote Node Name area, enter the Network Name and Control Point Name if they are required. The Network Name identifies the remote system's SNA network and is required if you will be using Format 3 XIDs. Likewise, the Control Point Name identifies the remote system on the SNA network and is required if Format 3 XIDs will be used. These two names work together to identify this system to the other network resources. For this reason, if either of the names is supplied, the other name should also be supplied. The SNA host system administrator should advise you as to whether these two names are required, and if so, what the names should be.

   
   When you are connecting to a host system, and you are using a remote Network Name, the name must match the NETID parameter in the VTAM Start command for the remote VTAM system. Also, the remote Control Point Name must match the SSCPNAME parameter in the VTAM Start command for the remote VTAM system. In such cases, the remote Network Name and the remote Control Point Name should be supplied by the remote system administrator.
   

   When used, each name can contain up to eight alphanumeric characters (including the special characters @, #, and $). Lowercase letters are automatically converted to uppercase.

   If this connection will access an AS/400 host, use the network name of the AS/400 in the Network Name box and the AS/400 name in the Control Point Name box.

5. Also in the Remote Node Name area, enter the Remote Node ID, an eight-digit hexadecimal value that uniquely identifies the remote host, peer, or downstream system. The remote system administrator should provide the proper value to enter. After the first three digits (the block number) of the Remote Node ID are typed, the cursor positions itself in the second half of the Remote Node ID box so that the remaining five digits (the node number) can be entered. The block number portion of the Remote Node ID cannot be 000 or FFF, and the node number portion cannot be 00000, as these values are reserved.

6. If you want to change the connection activation limit defaults (also called retry timers), click Retry Timers in the X.25 Setup dialog box. The two activation limits available for modification are described in the following list:
   • Maximum Number of Attempts. This is the number of times the SNA Server should attempt to establish the connection with the host. When the specified number of unsuccessful attempts has been made, the SNA Server quits trying and makes the appropriate entries in the event log. Any number of attempts can be specified, from 1 through No Limit, with No Limit being the default.

   • Delay After Failed Attempts. This is the number of seconds the SNA Server should wait after each failed attempt before it tries once again to establish the connection. The permissible range for this timer limit is from 5 seconds through 255 seconds, with 10 seconds being the default.

7. SNA Server is designed to provide reasonable defaults for the advanced X.25 settings, and under normal circumstances, these defaults work fine. If you want to accept the basic settings just entered and use the X.25 default advanced settings as well, go to step 9. Otherwise continue with step 8.

8. If you need to view and/or modify these advanced X.25 default settings, click Advanced in the X.25 Setup dialog box to expand the X.25 Setup dialog box to include the advanced settings. The advanced X.25 configuration settings are shown in figure 22.11 and described in the following list:

   Fig. 22.11 - When you click Advanced in the basic X.25 Setup dialog box, the dialog box expands to display the advanced configuration parameters for X.25 connections.

   • Packet Size. Either accept the default value of 128 or enter a new value from the following permissible set of values: 64, 128, 256, 512, or 1024. This value represents the maximum number of bytes, not including header information, that can be transmitted in a single frame. Coordinate with your network administrator to determine this value. Packet size is only applicable to connections using PVCs.

   • Window Size. Either accept the default value of 2 or enter a new value from 1 through 7 to represent the maximum number of frames the local system can send without receiving a response from the remote system. Coordinate with the remote system administrator to determine this value. Window size is only applicable to connections using PVCs.

   • PVC Alias. Either accept the default value of 1 or enter a new value from 1 through N (where N is the number of configured PVC channels) to identify the number of the channel. PVC alias is only applicable to connections using PVCs.

   • Facility Data. Enter up to 126 hexadecimal characters to request non-default X.25 network functions for a particular SVC connection. If required, this facility data information string can be obtained from your network and/or remote system administrator. The Facility Data box is only available for connections using SVCs.

   • User Data. Either accept the default value of C3 (specifies the QLLC protocol) or enter an even number of hexadecimal characters (32 maximum) to supply required user data to the network. One of the primary pieces of user information supplied in this way is the communications protocol used by the X.25 network. Required user data strings can be obtained from your network administrator. The User Data box is only available for connections using SVCs.

   • XID Type. Specify the type of identifying information the SNA Server should send. Two formats (types) can be selected: Format 0 and Format 3. When Format 0 XIDs are used, only the Node ID is sent. This type should only be used for hosts that do not support Format 3 XIDs that send up to 100 bytes of identification information, including the Local Node ID and Control Point Name. If independent APPC LUs are going to be used on this connection, Format 3 XIDs must be specified. Format 3 is also the default XID type.

   • Max BTU Length. Either accept the default value of 265 (host connections) or 1033 (peer connections) or enter a new value from 265 through 16393 to represent the maximum length of the basic transmission unit (BTU). A BTU, also known as an I-frame, is the number of bytes that can be transmitted in a single data-link control frame. If you are using a mainframe host connection, the Max BTU length should be equal to or less than the value specified for the MAXDATA parameter in the VTAM PU definition. If you are using a downstream connection, you should specify a Max BTU length equal to or less than the maximum supported value of the downstream system. Contact the host or downstream system administrator for the values to use.

9. Click OK to accept the settings and exit the X.25 Setup dialog box, or click Cancel to exit the dialog box without accepting the settings.

Completing Configuration of Channel Connections

The first step is really a continuation of the procedure described earlier for configuring common connection properties. The last step of that procedure is repeated in the first step here for continuity.

1. Click Setup in the Connection Properties dialog box to display the Channel Attached Setup dialog box (see fig. 22.12).

   Fig. 22.12 - This Channel Attached Setup dialog box is used to define the basic configuration parameters for a Channel Attached connection.

2. In the Channel Address box, either accept the FF default value or enter a two-digit hexadecimal number from 00 through FF that uniquely identifies this channel.

3. In the Local Node Name area, enter the Local Node ID, an eight-digit hexadecimal value that uniquely identifies the local SNA Server to the host system. After the first three digits (the block number) of the Local Node ID are typed, the cursor positions itself in the second half of the Local Node ID box so that the remaining five digits (the node number) can be entered. Be sure that you use the same Local Node ID for all the connections and link services on this SNA Server. The default Local Node ID value is 05D FFFFF. The block number portion of the Local Node ID cannot be 000 or FFF, and the node number portion cannot be 00000, as these values are reserved.

   
   Coordinate the Local Node ID value with the host system administrator so that corresponding VTAM parameters in the host system can be set up to match the Local Node ID. For host systems, the block number should match the IDBLK variable, and the node number should match the IDNUM variable in the VTAM PU definition.
   

4. If you want to change the connection activation limit defaults (also called retry timers), click Retry Timers in the Channel Attached Setup dialog box. The two activation limits available for modification are described in the following list:
   • Maximum number of attempts. This is the number of times the SNA Server should attempt to establish the connection with the host. When the specified number of unsuccessful attempts has been made, the SNA Server quits trying and makes the appropriate entries in the event log. Any number of attempts can be specified, from 1 through No Limit, with No Limit being the default.

   • Delay after failed attempts. This is the number of seconds the SNA Server should wait after each failed attempt before it tries once again to establish the connection. The permissible range for this timer limit is from 5 seconds to 255 seconds, with 10 seconds being the default.

5. SNA Server is designed to provide reasonable defaults for the advanced Channel Attached settings, and under normal circumstances, these defaults work fine. If you want to accept the basic settings just entered and use the Channel Attached default advanced settings as well, go to step 7. Otherwise continue with step 6.

6. If you need to view and/or modify these advanced Channel Attached default settings, click Advanced in the Channel Attached Setup dialog box to expand the Channel Attached Setup dialog box to include the advanced settings. The advanced Channel Attached configuration settings are shown in figure 22.13 and described in the following list:

   Fig. 22.13 - When you click Advanced in the basic Channel Attached dialog box, the dialog box expands to display the advanced configuration parameters for Channel Attached connections.

   • XID Type. Specify the type of identifying information the SNA Server should send. Two formats (types) can be selected: Format 0 and Format 3. When Format 0 XIDs are used, only the Node ID is sent. This type should only be used for hosts that do not support Format 3 XIDs that send up to 100 bytes of identification information, including the Local Node ID and Control Point Name. If independent APPC LUs are going to be used on this connection, Format 3 XIDs must be specified. Format 3 is also the default XID type.

   • Max BTU Length. Either accept the default value of 265 or enter a new value from 265 through 16393 to represent the maximum length of the basic transmission unit (BTU). A BTU, also known as an I-frame, is the number of bytes that can be transmitted in a single data-link control frame. If you are using a mainframe host connection, the Max BTU length should be equal to or less than the value specified for the MAXDATA parameter in the VTAM PU definition. Contact the host system administrator for the values to use.

7. Click OK to accept the settings and exit the Channel Attached Setup dialog box, or click Cancel to exit the dialog box without accepting the settings.

From Here...

• To review basic SNA concepts and SNA Server installation procedures, see Chapter 21, "SNA Server Preparation and Installation."

• For information on configuring the logical units and downstream connections so that clients can access network resources, see Chapter 23, "Implementing SNA Server."

• For information on managing the SNA Server on a daily basis as the SNA Server administrator, see Chapter 24, "The Role of the SNA Server Administrator."

• For information on using the Windows NT Server administrative tools as the SNA Server administrator, see Chapter 6, "The Role of the Network Administrator."

Table of Contents

21 - SNA Server Preparation and Installation

23 - Implementing SNA Server