gtps2m1rACF/SNA Data Communications Reference

Activating Links

The sequence of exchange identifier (XID) flows is the same for HPR support as it is for base APPN support. If a node supports HPR, additional information now flows in the XID. Whether an adjacent node supports HPR is determined dynamically during the XID process. The same is true for determining whether the adjacent node supports APPN.

If a node supports HPR, it includes control vector (CV) X'61' in its XID. Bits in CV X'61' indicate whether the node supports the RTP tower and control flows over the RTP tower. The ANR label assigned by this node to the link is also included in CV X'61'.

A link is HPR capable if, and only if, the XIDs sent by both sides include CV X'61'. If one or both XIDs do not include CV X'61', the link is base APPN and is not HPR capable.

If HPR support is enabled on the TPF processor where the link is being activated, CV X'61' is included in the XID sent by the TPF system. See Installation and Tuning for more information about how to enable HPR support in the TPF system.

A link that supports APPN, but does not support HPR, is limited to base APPN flows, meaning that only format identification 2 (FID2) path information units (PIUs) can flow across this link. An HPR-capable link supports not only FID2 PIUs, but also NLPs.

Because the TPF system is an APPN end node (EN), whenever a new link is activated, the TPF system sends a topology database update (TDU) request to register the new link in the APPN network. The TDU now includes HPR support information.

Use the ZNAPN command with the TOPOLOGY parameter specified to display information about the active PU 2.1 links connected to the TPF loosely coupled complex. The information displayed indicates whether the link supports HPR and, if so, whether the link connects to an RTP node or an ANR node. See TPF Operations for more information about the ZNAPN command.