The header format for OSPF is shown in the Fig.1.

OSPF header analysis is given below.

1.Version: This field specifies the protocol version.

2.Type: This field indicates messages as one of the following type.

a. Hello

b. Database description

c. Link status

d. Link status update

e. Link status acknowledgement.

3.Packet length: This field specifies the length of OSPF packet in bytes, including the OSPF header.

4.Router ID : It identify the sending router. This field is typically set to the IP address of one of its interfaces.

5.Area ID: This field identifies the area this packet belongs to (Transmitted) . 6.Checksum :The checksum field is used to detect errors in the packet. The checksum is performed on the entire packet.

7.Authentication type: It identifies the authentication type that is used.

8.Authentication : This field includes a value from the authentication type.