Figure 1(1) shows the latency for a send/recv operation inside the stack. This is a ``ping'' test in which a message is received, and an immediate response is sent back to the origin. The amount of time spent inside the Ensemble stack is measured. As we can see, the regular and authenticated stack are quite close, meaning that the computational overhead of an MD5 hash over a message is not significant. On the other hand, the encrypted stack is relatively expensive. As message size grows the computation required grows. For a 900 byte message the latency is 140 microseconds. Note that the base line is a low and constant 24 microseconds. Hence, the basic overhead imposed by the system is very low. Furthermore, the cost difference between the different stacks is almost entirely due to the MAC and encryption algorithms, not to the layering structure.
(1) (2) (3)
Figure 1: A standard stack is denoted REG. An authenticated stack is denoted AUTH. An authenticated encrypted stack is denoted SECURE. (1) send-recv latency in the Ensemble stack. (2) Total Latency for point-to-point send/recv. (3) Throughput.
These figures show rekey times, in milliseconds, as a function of group size. As we can see, the Diamond algorithm, which is specifically geared for single process failures, is much faster than the more general dLKH. However, dLKH will outperform Diamond in the event of multiple failures.
This document was translated from LATEX by HEVEA.