Security in Circuit, Message, and Packet Switching

Robert H. Greenfield, Computer Consulting

Daryle P. Niedermayer, CGI Group Inc.


Layering Models

OSI Reference Model

TCP/IP Model

Broadcast Model

Circuit, Message, and Packet Switching

Circuit Switching

Message Switching

Packet Switching

Security Considerations

Packet Addressing

Encrypted Packet Transmissions

Security Concerns with TCP Packets



Cross References


Further Reading


Circuit, message, and packet switching are techniques for transferring information. These concepts are not unique to electronic networking. They have common, everyday models and historical prototypes. A ubiquitous example of circuit switching is a voice telephone conversation between two people. Message switching is seen every day in the paper-based postal system.

Visualizing packet switching takes more imagination. Let's move a complete business including staff, furniture, files, business machines, and so forth from an old location to a new one. We assume that the business is sufficiently large that it needs several automobiles and buses to move the people and a number of trucks to move the nonhuman assets. All these vehicles, each containing a portion of the company, move over a system of roads. Each vehicle travels independently, yet as an aggregate, the company is the sum of the payloads of all the vehicles.

We look at security aspects of circuit, message, and packet switching for digital communications ...

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