HP-UX SNAplus2 R7 General Information

SNA Networking
Enterprise Extender
Because the BrNN appears as an End Node, it does not receive topology information from the backbone
network (topology information is transmitted only between Network Nodes).
The BrNN registers all resources in the branch with its NNS as though they were located on the BrNN itself.
This means that the nodes in the backbone network can locate resources in the branch without having to be
aware of the separate nodes in the branch.
To the branch network, the BrNN appears as a Network Node, acting as the network node server (NNS) for
End Nodes in the branch. Each node in the branch sees the rest of the network as being connected through its
NNS, in the same way as for a standard NNS.
1.3 Mixed SNA 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, enabling the hosts to perform as network nodes
in the APPN network; at the same time, the host provides an SSCP to control subarea SNA functions.
Many SNA networks reect their history, containing 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.
The following additional services are required to achieve this:
Dependent LU server (DLUS)
On the host, DLUS provides access to the old SSCP functions and acts as an interface to the APPN network.
Dependent LU requester (DLUR)
On a network node or end node, DLUR provides passthrough function to the host for dependent LUs.
This combination of DLUR and DLUS (generally known simply as DLUR) enables dependent LU trafcto
be transported over the APPN backbone. Existing SNA applications that use dependent LUs can be retained
without modication, while taking advantage of APPNs network management, dynamic resource location, and
route selection capabilities. In this way, DLUR provides a useful migration path from subarea SNA to APPN.
1.4 Enterprise Extender
Enterprise Extender (HPR/IP) provides a mechanism for integrating SNA applications with an IP network.
SNA applications are designed to use SNA protocols to communicate over SNA networks with other SNA
applications. When installed in a TCP/IP network using Enterprise Extender, SNA applications can still
communicate; the Enterprise Extender function provides a mechanism for transporting SNA protocols over the
IP network. In particular, it provides APPN High-Performance Routing (HPR) functionality, giving the applications
the benets of both APPN and IP connectivity.
Enterprise Extender in SNAplus2 is implemented simply as a communications link. To connect two SNA applications
over IP, you dene an Enterprise Extender link, in the same way as for any other link type such as SDLC or Ethernet.
17