HP-UX SNAplus2 R7 Administration Guide

SNA Terms and Concepts
Basic APPN Concepts
Figure 1–12 Branch Extender
APPN Backbone Network
Branch Network Node
End Nodes
Network Node Server
As the name implies, Branch Extender is designed for networks that can be divided into distinct areas such as
separate branches of a large organization. It works by separating out branches from the main backbone APPN
network (for example, the network in the organization’s headquarters).
Each branch contains a node of a new type called Branch Network Node (BrNN), which is connected to a Network
Node in the main APPN backbone network. The BrNN combines the functions of an APPN network node and an
APPN end node.
• To the backbone network, the BrNN appears as an End Node, connected to its Network Node Server (NNS) in
the backbone network:
• The nodes in the backbone network are not aware of the nodes within the branch, reducing the amount of
topology information that must be stored.
• 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 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.
37