Next-Hop Selection Algorithm over ECMP

A novel algorithm for next-hop selection over a set of equal cost multiple paths (ECMP) in a router is presented, which provides for load sharing among multiple routes. The main idea of proposed algorithm called prime number modulo-N (PMN) is that the remainders are distributed equally when the multiples of a number are divided by prime number. Based on this specific property, PMN assigns incoming flows to a next-hop selected. The hashed value of flow is divided by the number of multiple paths. If a next-hop pointed the remainder is available, this next-hop selected to forward packet. But if not, prime number not exceeding the remainder divides the hashed value and a next-hop is selected using this remainder. The disruption characteristic is remarkably improved using prime number division scheme The lookup performance of PMN is an optimal O(1) and disruptive behavior is between 0.14 and 0.54 in case N is the number of next-hops and N is equal to eight. And the disruption average of PMN is 0.32. In case N is equal to sixteen, disruptive behavior is between 0.07 and 0.61 and the disruption average is 0.26. The optimal disruption average is 0.16 where N is equal to sixteen. As compared with other algorithm decided which next-hop to use, the performance of PMN like modulo-N is an optimal O(1), disruptive behavior of PMN is better than that of modulo-N and that of hash-threshold algorithm. But highest random weight (HRW)'s disruptive behavior with 1/N is better than that of PMN. Load balancing per flow is nearly good if each flow has the same distribution in input packet streams