gtps2m1p | ACF/SNA Data Communications Reference |
There are two types of HPR nodes in the network:
- Automatic network routing (ANR) nodes, which can be only intermediate
nodes for a rapid transport protocol (RTP) connection.
- RTP nodes, which can be end points or intermediate nodes for an RTP
connection. RTP nodes support the RTP tower and, optionally, control
flows over the RTP tower. The TPF system is an RTP node. See RTP Connections for more information about RTP connections.
The major difference between an ANR node and an RTP node is the amount of
work that must be performed. In HPR support, most of the work is
performed by the two RTP nodes that are the endpoints of an RTP connection,
also known as RTP endpoints. RTP endpoints provide the following
functions:
- They detect failures in the network and then start the path switch process
to route the RTP connection around the failure. See Detecting Network Failures for more information.
- They provide end-to-end flow control. See Flow Control for more information.
- They provide the selective retransmission function, which includes
retransmitting specific messages that were lost in the network and requesting
that specific messages be retransmitted. See Selective Retransmission for more information.
- They segment output messages and reassemble input messages when
necessary. See Segmentation and Reassembly for more information.