1. OSPF packets are IP packets with protocol number 89.
1. OSPF packets use IP multicast addresses to transport routing information. The multicast addresses used depend on the OSPF message type and the destination of the packet.
1. OSPF packets contain a fixed-length header that includes information such as OSPF version, packet type, packet length, router ID, and area ID.
1. OSPF packets also contain one or more body fields where different types of information can be conveyed, such as router link state, network link state, or summary link state information.
1. OSPF packets use a checksum field to ensure the integrity of the packet. The checksum is calculated over the entire IP packet, including the OSPF header and body fields.
1. OSPF packets can be authenticated using a variety of authentication types, such as plain text, MD5, or SHA.
1. OSPF packets are typically exchanged between neighboring OSPF routers in order to build and maintain the routing table.
