TCP Header




The Transmission Control Protocol (TCP) is a standard transport layer that coordinates with the internet protocol to establish transmissions over networks. It uses the headers to transfer information across the network connections and they act as a part of the packaging message. The TCP packets are usually transmitted as internet datagrams. TCP headers are also comprised of a set of criterion which are described by the technical specifications of the protocol.




Each header of the TCP consists of twenty bytes totaled by the ten needed fields. These fields include Source and destination port numbers, sequence number, acknowledgement number, TCP data offset and Reserved data. The layout also consists of Control flags, Window size, TCP checksum, Urgent Pointer and TCP optional data. All these fields have their own size in the TCP header layout and execute different functions.

The Source and Destination port numbers have two bytes each, and are the endpoints of communication through which information is conveyed by the sending devices and receivers.

The sequence numbers have a total of 4 bytes and are used by the senders to assign group of messages that have to be ordered. The acknowledgement numbers are utilized by both the receiver and the sender to communicate the sequence numbers of previously received messages or ones that are yet to be sent.

TCP headers have the reserved data which has a zero value. It aligns the size of the total header and is useful in computer data processing. The alignment is executed as a multiple of four bytes. The protocol sender generates the checksum value of the TCP header in an approach that enhances detection of corrupted messages.

The urgent pointer field is usually used as a data offset and can assign a subset of an information. It is often ignored the fact that it is set to have a value of zero. The TCP optional data helps in window scaling algorithms and supports a unique acknowledgement. Window size are used by the senders for regulation of information to be sent to the destination before exchanging an approval. In a case where the window size is smaller in size, the network transfer of information will tend to be slower in its operations unnecessarily.

On the contrary, a bigger window size saturates the entire connection. The receiver might also fail to interpret the incoming information at a faster rate which also results to a low performance. They have been designed to automatically calculate the value sizes. They also utilize the TCP headers in co-relating dynamic changes between the source and receiver.

The data Offset field is useful in storage of the TCP header size in 4 bytes. A data offset of five which represents 20 bytes characterizes a header that doesn’t utilize the optional TCP field. A data offset of fifteen represents 60 bytes and depicts a header that utilizes the maximum size of the optional TCP field.




The control flags are utilized by the Transmission Control Protocol (TCP) to handle the flow of data in special occasions. The TCP connection reset logic can be initiated by a single control flag to manage the transmission of information.