Its used to detect an error if the packet may be mis-routed. I'm not 100% sure.
In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.
Only TCP will automatically discard a packet with a bad checksum. UDP packets have a checksum field, but it is rarely used, and then only by the application (not UDP itself)
It is a TCP Header
a tcp header contains the information of the source and destination networks and well as what port to access with out it the packet would not know where to go
both tcp and udp
• checksum • destination port • source port
An Ethernet frame has a 14 byte header, a data section, and a 4 byte trailer 14 byte header consist of destination address, source address and type The trailer is for CRC (Cyclic redundancy Check) An Ethernet frame can contain an IP and TCP PDU. IP header most important parts consists of (Version,IHL, Total length,Protocol, source and destination address) In details (Version,Header length,Differentiated services field, total Length, Identification, Flags, fragment offset, Time to live, protocol, header checksum, source and destination address). TCP header most important parts consists of (Source port, Destination port and header Length) In details (Source Port, Destination Port, Sequence number, Acknowledgment number, Header length,Flags,Window and check sum). The details of the IP and TCP header have been taken from a Network protocol Analyzer Wireshark on my own pc.
The sequence number, acknowledge number, and Window fields.
time to live
A UDPheader contains four 16-bit fields. They are the source port, destination port, length, and checksum -- in that order.
To reassemble the segments into data.
2^16 bytes - size of TCP header