OSPF with IP unnumbered
I have come around a challenge that two routers connected directly to each other but use different IP subnets. For the purpose of adjacency to form, OSPF has constraint devices connected interfaces to be in same subnet. So, after a search I found followed method. change the opsf network type of the router to point-to-point assign the ip unnumbered to the directly connecting interfaces create new loopback and assign the ip address which previously on directly connected interface advertise networks with ospf network command. General idea here is, in point to point link, ip address is does not matter as packet leaving the sender and will receive only by one receiver as only two participants in the Point-to-Point link. Not like multi access networks, where it is required to ensure the intended recipient has to receive the sender's packet among multiple receivers. Let's dig into detail with followed diagram Diagram details: R1 and R3 connected with ...