Blocking and Delay Analysis of Optical Buffer with General Packet Length Distribution

Buffers are essential components of any packet switches for resolving contentions among arriving packets. Currently, optical buffers are composed of Fiber Delay Lines (FDL), whose blocking and delay behavior differ drastically from that of conventional RAM in at least two folds: (i) only multiples of discrete time delays can be offered to arriving packets; (ii) a packet must be dropped if the maximum delay provided by optical buffer is not sufficient to avoid contention, this property is called balking. As a result, optical buffers only have finite time resolution, which may lead to excess load and prolong the packet delay. In this paper, the closed-form expressions of blocking probability and mean delay are derived to explore the tradeoff between buffer performance and system parameters, such as the length of the optical buffer, the time granularity of FDLs, and to evaluate the overall impact of packet length distribution on the buffer performance.