LU 6.2 API Application Programmer's Reference Guide (30294-90008)

20 Chapter1
The SNA Network and LU 6.2 API
Systems Network Architecture (SNA)
Figure 1-1 Node Types in an SNA Network
Peer-to-Peer Communication
As computers have become smaller and less expensive, companies have
replaced cluster controllers with computers like the HP 3000 that
adhere to Node Type 2 protocols. Using an HP 3000 as a cluster
controller allows a remote location to have local processing power as
well as a connection to the mainframe computer.
A newer version of the Type 2 node allows remote processors to take
advantage of their local processing power and perform more complex
data communication functions than traditional Type 2 nodes. This
newer node type is called Node Type 2.1, and the older Node Type 2 is
now referred to as Node Type 2.0. Type 2.1 nodes, or peer nodes, can
establish direct connections between themselves without having to rely
on a mainframe or a communications controller to manage data traffic.
Communication between Type 2.1 nodes is called peer-to-peer
communication.
IBM AS/400s function as Type 2.1 nodes. HP 3000s running MPE XL
can also function as Type 2.1 nodes. Figure 1-2 shows an SNA network
without a host node, where two AS/400s and one HP 3000 communicate
peer-to-peer as Type 2.1 nodes.