s = format (s, "via %U ", format_ip6_address, mp->next_hop_address);
else
s = format (s, "via %U ", format_ip4_address, mp->next_hop_address);
s = format (s, "via %U ", format_ip6_address, mp->next_hop_address);
else
s = format (s, "via %U ", format_ip4_address, mp->next_hop_address);