Selected IP v4 Packet Header Fields
Version (4 bits): The IP version number
Time to live (8 bits): The number of router hops left before the packet is discarded.
Source address (32 bits): The IP address of the host sending the packet.
Destination address (32 bits): The IP address of the host the packet is being routed to.
Total length (16 bits): The total length of the packet, in bytes.
Data (variable length): The actual data being sent between the hosts.
Selected TCP Frame Header Fields
Source port (16 bits): Identifier of the program that sent the data.
Destination port (16 bits): Identifier of the program that should receive the data.
Sequence number (32 bits): The sequence number of this frame in the session.
Checksum (16 bits): A number the sending host computes based on the frame contents. It is recalculated by the receiving host to be sure the data is correct.
Selected IP v6 Packet Header Fields
Version (4 bits): The IP version number
Priority (4 bits): The priority is used to differentiate data like e-mail where speed is not of the essence from more demanding data like router-control information or audio or video data streams.
Flow label (24 bits): Identifier of information that will guide the routers in quickly passing packets that are of high priority.
Source address (128 bits): The IP address of the host sending the packet.
Destination address (128 bits): The IP address of the host the packet is being routed to.