The overhead in dispatching packets in the traffic nodes is determined
by hardware and is small, approximately 650 ns. This will not in general
be the case when interfacing links to a microprocessor. To demonstrate
the effect of the packet overhead the dispatching delay has been artificially
increased. Figure 8 shows the dependence of network throughput on
packet overhead for a 128 node Clos under random traffic. The fall
off in performance is particularly marked for short packets; the throughput
drops by nearly an order of magnitude when the overhead is increased
from 10 to 100 
s. This underlines the importance of an efficient
processor to link interface.