On aggregation in almost all optical networks

Based on discrete time Markov Chains, we develop an exact mathematical model for the performance evaluation of packet aggregation on the edge router of an optical network. This device works as an interface between the electronic and optical domains: it receives IP packets from the client layer and converts them into optical packets to be sent inside the optical network. We suppose the optical packet to be of constant length. To reduce the aggregation delay, a timer is added to the aggregation mechanism, in such way that an optical packet is transmitted whether the timer expires or the aggregation unit becomes full or cannot accommodate more IP packets. We derive closed formulas for the probability density function of the aggregation delay, the optical inter transmission time, and of the transmitted optical packet length. Performance measures such as aggregation delay and efficiency show the importance of the timer in bounding the delay of transmitted packets without much altering the aggregation efficiency.