MFCHASH
hash = MFCHASH(origin.s_addr, mcastgrp.s_addr);
hash = MFCHASH(ip->ip_src.s_addr, ip->ip_dst.s_addr);
for (rt = mfctable[MFCHASH(o,g)]; rt; rt = rt->mfc_next)
hash = MFCHASH(mfccp->mfcc_origin.s_addr, mfccp->mfcc_mcastgrp.s_addr);