On the spatial capacity of packet radio networks

Pacing Control, Mischa Schwartz (on leave from Columbia University). In this paper a model and analysis is provided of the IBM SN.' virtual route pacing control umd to control congestion in SNA networks. The model is appropriate to single virtual routes only. The analysts uses a Norton equivalent of the virtual route queueing model. Similar analyses of two other end-to-end window control mechanisms are carried out; one a .~liding window with each message individually acknowledged, the other a fixed window control with the final message in the window only producing an acknowledgement, enabling comparisons to be made between all three. The SNA pacing control procedure, in which the first message in a given window induces an acknowledg,~'ment, is found to perform within 4% of the sliding window mechanism. Simulation results validate the analysis and performance curves obtained. The third wh~dow scheme, with the final message in the window generating an acknowledgement, is found to result in considerable reduction in throughput, as expected. [IBM Research Report RC 8490, September 1980; IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598).