Security in Circuit, Message, and Packet Switching
Robert H. Greenfield, Computer Consulting
Daryle P. Niedermayer, CGI Group Inc.
OSI Reference Model
Circuit, Message, and Packet Switching
Encrypted Packet Transmissions
Security Concerns with TCP Packets
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 ...