carp_cksum
ch.carp_cksum = 0;
ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip));
ch_ptr->carp_cksum = carp6_cksum(m, sizeof(*ip6),
if (carp_cksum(m, len - iplen)) {
u_int16_t carp_cksum;