HP HP-UX SNAplus2, Administration Manual

Page: 64 / 398

64 Chapter 1
SNA Terms and Concepts
Accessing Subarea Networks from APPN Networks
Accessing Subarea Networks from
APPN Networks
Although APPN networks do not require a host to control resources in
the network, hosts often participate in APPN networks. APPN has been
implemented on many host platforms, and allows the hosts to perform as
network nodes in the APPN network while still providing an SSCP to
control any old subarea SNA function.
Many SNA networks contain elements of both subarea SNA and APPN.
The backbone of the network is built from network nodes that must
bridge the gap between a dependent LU and the facilities on the host.
Two additional services are required to achieve this:
• Dependent LU server (DLUS) on the host provides access to the old
SSCP functions and interfaces to the APPN network.
• Dependent LU requester (DLUR) on a network node or end node
provides a means of transporting session traffic from dependent LUs
to a host through an APPN network. This function enables dependent
LU sessions to take advantage of the more versatile routing functions
provided by APPN.
This combination of DLUR and DLUS (generally known simply as
DLUR) allows dependent LU traffic to be transported over the APPN
backbone. Existing SNA applications that use dependent LUs can be
retained without modification, while taking advantage of APPN's
network management, dynamic resource location, and route selection
capabilities. In this way, DLUR provides a useful migration path from
subarea SNA to APPN.
The dependent LU does not need to reside on the node that provides the
DLUR function. If the DLUR function is provided by a network node, the
dependent LU can be on an adjacent network node, end node, or LEN
node. If the DLUR function is provided by an end node, the dependent
LU must be on the end node itself.