OSPF networks are classified into four types of networks by link layer protocol.

Network Types and Corresponding Link Layer Protocols

Broadcast : Ethernet

Point-to-Point (P2P) : PPP, HDLC

Point-to-Multipoint (P2MP) : PPP

Non-Broadcast Multi-Access (NBMA) : Frame Relay

 OSPF Network Types:

OSPF classifies networks based on link layer protocols into the following types:

Broadcast: This type assumes that all routers on the network can communicate directly with one another using multicast or broadcast frames. Ethernet networks are typical examples.

Point-to-Point (P2P): This type is used for links that connect two routers directly. Common protocols include PPP (Point-to-Point Protocol) and HDLC.

Point-to-Multipoint (P2MP): This type simulates multiple point-to-point connections over a single physical network, often used in WAN scenarios where PPP is employed.

Non-Broadcast Multi-Access (NBMA): These networks connect multiple devices but lack native broadcast capability, such as Frame Relay.