— In reliable multicast, data packets can be cached at some nodes such as repair servers for future possible retransmission in loss recovery schemes. How to cache packets to optimize the performance of loss recovery is an important issue in reliable multicast protocol design. In this paper, we present a general solution which addresses the main design problems of caching policies. We first formulate the caching policy design as an optimization problem by employing caching utility as a uniform measure. Based on caching utility, we propose an algorithm called Optimal Caching Time (OCT) for configuring the caching time of packets and demonstrate that it solves the optimization problem. Furthermore, we analyze the performance improvement of OCT caching policy compared to the existing caching policies such as FIFO, Probabilistic FIFO (P-FIFO), and Timer-Based Caching Policy (TBCP). We use ns-2 simulations to demonstrate the performance gains brought by OCT caching policy. The numerical ...