prefix_cmp
int prefix_cmp(struct prefix *, struct prefix *, int *);
if (prefix_cmp(a, b, &dummy) < 0) {
} else if (prefix_cmp(b, a, &dummy) > 0) {
int prefix_cmp(struct prefix *, struct prefix *, int *);
np->dmetric = prefix_cmp(pp, np, &testall);
if ((preferred = (prefix_cmp(new, xp, &testall) > 0))) {
prefix_cmp(old, xp, &testall);
prefix_cmp(old, xp, &testall);
prefix_cmp(afi, prev_ip_addr, &ip_addr) != -1) {
return prefix_cmp(a->afi, &a->prefix, &b->prefix);