Network type supported by OSPF
1.P2P network:
Only two routers are interconnected
Support broadcast, multicast packet forwarding
2.Broadcast network
The broadcast network supports two or more devices to access the same shared link and can support broadcast and multicast packet forwarding. It is the most common network type of OSPF.
At the same time, because there are multiple devices in a broadcast network, neighbor relationship establishment and link information synchronization. OSPF has corresponding features to reduce the adverse effects of multiple devices on the same network.
The above two network types are the most common, in addition to two rare network types
3.NBMA network
Two or more routers are interconnected via VC
Unlike broadcast networks, NBMA does not support broadcast and multicast packet forwarding by default.
On an NBMA network, OSPF simulates operations on a broadcast network, but each router's neighbors need to be manually configured.
Example of an NBMA type network: a router network connected through a fully interconnected frame relay link
In today's network deployments, NBMA networks are rare.
4.P2MP network
Considering a non-broadcast network as a group of P2P networks, such a non-broadcast network becomes a P2MP network. On a P2MP network, the OSPF neighbors of each router can be discovered using Inverse ARP. P2MP can be regarded as a collection of multiple P2Ps, and P2MP can support broadcast and multicast forwarding.
No link layer protocol belongs to the P2MP type network by default, which means that it must be forced to be changed to P2MP by other network types. A common practice is to change a non-fully connected frame relay or ATM to a P2MP network.
