Question

What is a message called that is delivered by TCP? What is a message called that is delivered by UDP? At which layer do the two protocols work?

Answer 1

Answer:

• Transmission Control Protocol is a Transport Layer protocol.  
• This protocol is connection oriented which means that a connection is set up before the data packets are transmitted between the source and destination host which is a very reliable way of data transmission.
• The connection is established between the source and the destination, after this the data is transmitted between them and lastly the connection is ended or terminated after the data transmission.
• The packet or a messages that is delivered by TCP is called segment.
• Basically TCP divides the data into small parts or chunks which are called segments.
• The segment has a header and data section.
• The segment header is further divided into the following parts.
• Source port (sending port), destination port (receiving port), sequence number which is allocated to the first byte in the segment so that if the segments at the destination are sent out of order then it will help to rearrange these segments, Acknowledgement Number is number that the acknowledgement number sender expects to receive, header length, control flags which are used to control connection set up, connection termination and flow control, window size that a sender is ready to receive, Checksum field enables error control, Urgent pointer which is used to refer to data that is urgently needed to reach the receiving phase as soon as possible.  
• User Datagram Protocol (UDP) is a Transport Layer protocol and a part of Internet Protocol suite.
• This protocol is connection-less which means there  is no need to establish a connection between source host and destination host prior to the transmission of data which is an unreliable data transmission way.
• The message in UDP is called datagram .
• Unlike TCP segments there is no need to consider the order in which datagrams are sent or received.
• Datagram has a header part which contains routing information a data section which shows the data to be transmitted.
• Header has source port, destination port, checksum and length fields.
• TCP and UDP protocols work in Transport Layer.
• This layer is responsible for end to end delivery of data between source and destination hosts.
• It ensures reliable data transmission and manages flow control and also ensures that packets reach in the right order in which they were sent.