Windows in the sky—Flow control in SNA networks with satellite links

Geosynchronous communications satellites provide a unique means of high-speed computer-to-computer transmission of large volumes of data over long distances. The physical distances involved in transmitting to and from the satellites cause relatively long propagation delays for messages. In order that the high bandwidth be used effectively, large quantities of data have to be transmitted before pausing for an acknowledgment. This condition creates a potential for some new and unique types of traffic jams. This paper discusses these situations in the context of Systems Network Architecture (SNA) networks. In particular, the issues related to SNA's flow control and traffic management facilities in the presence of satellite links are discussed, along with potential solutions to ensure efficient network operation.