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The TCP/IP Guide  9  Networking Fundamentals       9  Fundamental Network Characteristics

Circuit Switching and Packet Switching Networks 1 2 3 Messages: Packets, Frames, Datagrams and Cells

In the previous topic I described and contrasted networking technologies based on whether or not they use a dedicated path, or circuit, over which to send data. Another way in which technologies and protocols are differentiated has to do with whether or not they use connections between devices. This issue is closely related to the matter of packet versus circuit switching.

Protocols are divided into two categories based on their use of connections:

• Connection-Oriented Protocols: These protocols require that a logical connection be established between two devices before transferring data. This is generally accomplished by following a specific set of rules that specify how a connection should be initiated, negotiated, managed and eventually terminated. Usually one device begins by sending a request to open a connection, and the other responds. They pass control information to determine if and how the connection should be set up. If this is successful, data is sent between the devices. When they are finished, the connection is broken.
  
  
• Connectionless Protocols: These protocols do not establish a connection between devices. As soon as a device has data to send to another, it just sends it.

Circuit Switching and Packet Switching Networks 1 2 3 Messages: Packets, Frames, Datagrams and Cells