TABLE OF CONTENTS This chapter shows how embedded systems can use the User Datagram Protocol (UDP) and the Transmission Control Protocol (TCP) to send messages over a network. The messages can contain any type of data. The systems must support IP, because TCP and UDP use IP addresses to identify a message s source and destination. The In Depth section of the chapter discusses UDP and TCP in detail, including when to use each and what s involved in supporting the protocols in an embedded system.
UDP and TCP are standard, well-supported protocols for computers that need to send and receive messages within local networks or on the Internet. Many application protocols transfer information using UDP or TCP. For example, a computer that sends a request for an IP address to a DNS server places the request in a UDP datagram. A request to a server for a Web page and the page sent in response both travel in TCP segments. But you can also use UDP and TCP to transfer messages of any type, including information in application-specific formats.
In general, UDP is a simpler protocol to implement but has no built-in support for acknowledging receipt of messages, determining the intended order of messages, or flow control. If you use a module with support for both UDP and TCP, the programming effort to use the protocols is likely to be about the same for each. In some cases, TCP programming may be easier.
This section presents examples of UDP and...
