IPv4 point to point addresses

In order to conserve IPv4 addresses, it is possible to use a /31 prefix for a point-to-point link. In such a case, such a subnet will have only two IP addresses, both of which will be used as host addresses. There are no network or broadcast addresses in such a scenario.

When such an address space is being advertised using a routing protocol, it is still the first address that is installed in the routing table. For example, for the subnet, there are two host addresses, specifically and Even so, if advertised by a routing protocol, would appear in the routing table as the network address. The following is an example of a routing entry advertised via OSPF:

O [110/2] via, 00:02:45, GigabitEthernet0/1