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.