It identifies the combined length of UDP Header and Encapsulated data. UDP (RFC 768) header encoder/decoder class. So 0x1c175 + 0x0011 + 0x0! UDP uses a concept called as "pseudo header". 4. Connectionless service UDP provides connectionless service. If header compression is used, the total for the IP/UDP/RTP headers will be only 2 bytes. The number in the length column is the total size of the captured frame (ethernet + ip) in your case 214. answered Dec 30, 2016 at 10:20. I tend to break a Wireshark capture down and try to correlate that to the three most relevant layers and their headers L2-L4. . UDP Segmentation Offload (USO) - Windows drivers | Microsoft Docs Similarly, if the value in this field is 10, then the length of the header will be 10 x 4 = 40 bytes. What are Ethernet, IP and TCP Headers in Wireshark Captures The length field specifies the number of bytes in the UDP segment (header plus data). UDP checksum calculation on improperly padded packets UDP Header Format is shown. I noticed that UDP has a total length field (bytes 5 & 6) but TCP does NOT! This requires buffering 2 words inside the module so the 2-word-length header can be transmitted to IP_send before the actual data. UDP Segmentation Offload (USO) - Windows drivers | Microsoft Docs It is a 16-bits field. The UDP header consists of four fields each of 2 bytes in length: Source Port (UDP packets from a client use this to indicate the session on the local client that originated the packet.) Checksum - The checksum allows the receiving device to verify the integrity of the packet header and payload. . IPV4 header format is 20 to 60 bytes in length. This document describes a robust method for calculating checksums for use with UDP Options. TCP header contains information for both compulsory and optional functions. The header also identifies the next layer up protocol. TCP vs. UDP - Lifewire ; Destination UDP port number (2 bytes): The destination UDP port number is the communication endpoint for the receiving device. This is based on the IP checksum calculation, but uses an updated pseudoheader. UDP — Ryu 4.34 documentation - Read the Docs . Calculation of TCP Checksum - GeeksforGeeks