TCP Header Starting Source port Destination port sequence Sequence number number(byte offset) of data Acknowledgment carried in this HdrLenlo flags Advertised window packet Checksum Urgent pointer Options(variable) DataTCP Header Starting sequence number (byte offset) of data carried in this packet 44 Source port Destination port Sequence number Acknowledgment HdrLen 0 Flags Advertised window Checksum Urgent pointer Options (variable) Data