Design, Performance

We demonstrate that the Internet has a formula linking de-mand, capacity and performance that in many ways is the analogue of the Erlang loss formula of telephony. Surpris-ingly, this formula is none other than the Erlang delay for-mula. It provides an upper bound on the probability a flow of given peak rate suffers degradation when bandwidth shar-ing is max-min fair. Apart from the flow rate, the only rel-evant parameters are link capacity and overall demand. We explain why this result is valid under a very general and re-alistic traffic model and discuss its significance for network engineering. Categories and Subject Descriptors C.2.5 Local and wide-area networks –Internet, C.4 Perfor-mance of systems – modeling studie