OSPF adjacency is established when two OSPF routers have matching interface parameters. This includes the OSPF router ID, network address, area ID, and other OSPF-specific configurations such as MTU size and network type. For example, the configuration commands provided in the image description suggest setting the OSPF router ID, network address with a wildcard mask, and specifying the OSPF area. Additionally, the interface is set to a point-to-point network type with a specific MTU size, which is important for OSPF adjacency as mismatched MTU sizes can prevent OSPF neighbors from forming an adjacency.

References: For a comprehensive understanding, refer to the “Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR)” official Cisco documentation and study guide,