Abstract: A novel routing algorithm, LRPI (low-overhead routing with piggybacked immunity information) was proposed. LRPI contains the following four new mechanisms: piggybacking the immune information with SV(summary vectors), fast generation of the immune information through a cross-layer method, an improved exchange mechanism of SV, and adaptive compression of SV. Based on the above new mechanism, LRPI not only avoids using special data structure but also can achieve the same immune function more quickly. Theoretical analysis and simulation results show that LRPI outperforms the classical epidemic routing algorithm and a few of its improvements in terms of control overhead, the number of saved packets, and average end-to-end delay.