Peripheral-node addresses, which are considered local addresses, differ depending on whether the node is T2 or T2.1. Subareas exist within domains in SNA subarea routing. Routing APPN routing is dynamic and is based on a least-weight path calculated from input received from all APPN network nodes. Topology information is passed until all APPN nodes receive it. When a node receives data it already has, it stops forwarding the data to other nodes.
Duplicate information is recognized via a check of update sequence numbers.
APPN network nodes link to ENs, LENs, and other network nodes. Several underlying functions and capabilities enable APPN routing. Routing Node Type 2.1 routing involves routing traffic between one or more APPN network nodes. The ISR process involves bind session BIND requests and responses flowing from network node to network node. With ISR, a map is generated of the session identifier and port from one side of a node to the other.