INFO: SNA Distinction Between XID Format 0 and Format 3

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Format 3

Format 3 is required to support independent LU6.2 sessions, and it is used to uniquely identify a PU 2.1 node to the adjacent node in the SNA network. A PU2.1 node can support independent LU6.2 as well as LU0, 1, 2, 3, and dependent LU6.2 sessions. When SNA Server sends a format 3 XID, the following information is sent:

• The Local Node ID configured in the connection dialog.
• The local SNA Server's fully qualified control point name (made up of the network name and control point name specified in the Server Properties dialog box), if configured.
  
  NOTE: The local SNA Server network name and control point name does not need to be configured to support independent LU6.2 sessions to a host. However, this information is required when you connect to an APPN network node, such as to an AS/400, a 3174 network node, or to VTAM if the "CPNAME" parameter is coded in the PU definition and the IDBLK and IDNUM parameters are not configured.
• Bytes 6-18, as defined in the IBM SNA [ASCII 147]Formats Guide[ASCII 148] Chapter 2 (IBM# GA27-3136).
• Various control vector information, such as Product ID subvector (as documented in Chapter 2 of the SNA Server 2.11 [ASCII 147]Reference Guide,[ASCII 148] page 25).

Format 0

Format 0 is used to uniquely identify PU2.0 nodes that rely on the host domain's System Service Control Point (SSCP). Examples of this configuration are PUs that support Dependent LU6.2 and LU0, 1, 2, 3 sessions. Format 0 uses the bytes 2-5 of its XID command to send the Block Number (idblk) and Node Number (idnum) for its unique identification. See the IBM SNA [ASCII 147]Format Guide[ASCII 148] XID I-fields chapter for details. You can configure this in the following location in SNA Server Admin:

1. For SNA Server version 2.11, select the Connection Properties located in the Servers and Connections window of SNA Admin. For SNA Server versions 3.0 and 4.0, go to the Connections folder, select the appropriate connection, and view the Properties window with the System Identification tab.
2. For SNA Server version 2.11, select the Setup button and configure the Local Node ID from the Local Node Name section. For SNA Server versions 3.0 and 4.0, the change can be made to Format 0 under Connections; select the appropriate connection, go to the Properties window with the System Identification tab, and select Format 0.

If SNA Server is configured to support 3270/Dependent LUs only, then either Format 0 or Format 3 will work. Contact the host administrator to determine which one to use.

To toggle SNA Server between XID types, do the following:

1. For SNA Server version 2.11, select the Connection Properties located in the Servers and Connections window of SNA Admin. For SNA Server versions 3.0 and 4.0, go to the Connections folder, select the appropriate connection, and view the Properties window with the System Identification tab.
2. For SNA Server version 2.11, select the Setup button, and then select the Advanced Button; you will see the XID Type dialog box. For SNA Server versions 3.0 and 4.0, the change can be made to Format under Connections; select the appropriate connection, go to the Properties window with the System Identification tab, and select Format 0 or Format 3.