This tool allows you to easily see what each protocol adds to your packet. A nice and easy to understand example of UDP checksum calculation is done by Gerd Hoffmann. The Fields of the Pseudo IP header are:-. Length - 16 bits. The size of the 6th row representing the Options field vary. TCP packets are part of a stream, a fragment of the whole stream. The length of UDP payload for selected packet is 32 bytes. networking - Why UDP header has 'length field'? - Stack Overflow IPV4 Header Format explanation with an Example Header I tend to break a Wireshark capture down and try to correlate that to the three most relevant layers and their headers L2-L4. PDF Chapter 14 User Datagram Program (UDP) Hex Packet Decoder If all of the bits in this field were "on," the maximum value would be 15. IP of the Source. The maximum length of a TCP segment is described in . Assume we have a ethernet link with an MTU of 1300 bytes, while an application want to send 5200 bytes of data. The udp_send module does the first step of this. IP Fragmentation Calculator - GitHub Pages UDP is faster, simpler, and more efficient than TCP. Because the length of the header may vary, the actual length depends on the presence or absence of the optional parameters. I left out UDP since connectionless headers are quite simpler, e.g. UDP header contains information only about the compulsory functions and it is 8 bytes in the length. The UDP Length field. Note that TCP does not define "total length" like UDP does, but rather . To calculate UDP checksum a "pseudo header" is added to the UDP header. It displays information such as the IP version, the packet's length, the source, and the destination. This means that the content of the "pseudo-header", which is used for TCP checksum calculation . TCP Throughput Calculator - Tools - SWITCHlan - SWITCH The length of the data is the length of the whole packet — the length of the header i.e. For Ethernet, no compression is allowed and the frame flag is equal to zero. This makes header length = 32 bytes. If it was padded, the length field tells you the actual length. src mac . The number in the length column is the total size of the captured frame (ethernet + ip) in your case 214.