Four devices form a square-shared network. Why cannot P2P interfaces in the same VLAN establish an OSPF neighbor relationship?

A: A Hello packet sent by a device are broadcast in the entire VLAN because the four interfaces are in the same VLAN and the Hello packet is sent in multicast mode. After receiving the Hello packet from an P2P interface, another device immediately attempts to establish an OSPF neighbor relationship because the P2P interface does not check the mask in the Hello packet. Because an P2P interface can establish only one neighbor relationship, the device ignores the Hello packets sent by other devices. As a result, the neighbor relationship is always in the Init state.

•  If A sends a Hello packet and B receives the Hello packet, A considers B as its neighbor.
•  If B sends a Hello packet and C receives the Hello packet, B considers C as its neighbor.
•  If C sends a Hello packet and D receives the Hello packet, C considers D as its neighbor.
•  If D sends a Hello packet and A receives the Hello packet, D considers A as its neighbor.

As a result, a dead loop occurs, causing a failure to establish an OSPF neighbor relationship.