HP-UX SNAplus2 General Information (October 1998)

Chapter 2 27
Introducing SNAplus2
SNAplus2 Resources
multiple ports for a single adapter. In this case, the
different ports are distinguished by addresses such as
the service access point (SAP) number.
Link stations
A link station (LS) represents the logical path through
the SNA network between the SNAplus2 local node
and a remote computer. The remote computer can be
any of the following:
• A host computer
• A peer computer, with SNAplus2 and the remote
computer communicating as equal partners (the
typical arrangement in an APPN network)
• A downstream computer that uses the SNAplus2
PU concentration to access a host
A link station is associated with a specific port; one or
more link stations can be associated with each port.
Each link station has an associated PU (physical unit).
Because such PUs are associated with link stations,
SNAplus2 does not treat them as separate resources;
they are configured as part of link station
configuration, and started and stopped as part of
starting and stopping link stations.
If a remote node attempts to connect to the local node,
and a suitable port is defined on the local node, but no
link station is defined that matches the address
specified on the incoming call, SNAplus2 can define a
dynamically created link station for the duration of the
connection.
Connection networks (CNs)
In an APPN network, an end node is often connected
only to a single network node, and each network node
is connected only to its nearest neighbors. Any node in
the network can communicate with any other node,
even if there is no direct connection between them,
because the communications path can be established
through the intermediate nodes.
If all the end nodes and network nodes are connected to
the same FDDI, token ring or Ethernet network, there
is a direct communications path between all nodes, so
that in theory any two nodes can communicate directly.