SNA Distinction Between XID Format 0 and Format 3

• Microsoft SNA Server for Windows NT, versions 2.0, 2.1, 2.11 and 2.11 Service Pack 1

SUMMARY

SNA Server supports two types of XIDs: Format 0 and Format 3. XIDs are used to uniquely identify a Physical Unit (PU) to the SNA Network. Depending on the type of PU defined, a particular XID format may have to be used.

MORE INFORMATION

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 Formats Guide 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 Reference Guide, 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 Format Guide XID I-fields chapter for details. You can configure this in the following location in SNA Server Admin:

1. Select the Connection Properties (located in the Servers and Connections window of SNA Admin).

2. Select the Setup button and configure the Local Node ID from the Local Node Name section.

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

1. Select the Connection Properties (located in the Servers and Connections window of SNA Admin).

2. Select the Setup button, and then select the Advanced Button. You will see the XID Type dialog box.