Guidelines for Using Socket Types

If you are communicating with an existing application, you must use the same socket type and the same protocol as the existing application.

Raw sockets have a special purpose of interfacing directly to the underlying protocol layer. If you are writing a new protocol on top of Internet Protocol (IP) or wish to use the Internet Control Message Protocol (ICMP), then you must use raw sockets.

You should consider the following factors in choosing a socket type for new applications:

• Reliability: Stream and sequenced packet sockets provide the most reliable connection. Connectionless datagram and raw sockets are unreliable because packets can be discarded, duplicated, or received out of order. This may be acceptable if the application does not require reliability, or if the application implements the reliability on top of the sockets API.

• Performance: The overhead associated with reliability, flow control, packet reassembly, and connection maintenance degrades the performance of stream and sequenced packet sockets so that these socket types do not perform as well as datagram sockets acting in a connectionless mode.

• Amount of data to be transferred: Datagram and sequenced packet sockets impose a limit on the amount of data transferred in each packet.