Large companies, telephone companies, and Internet companies measure traffic in gigabits per second, since their systems combine hundreds or even thousands of transmissions using the same connection. Calculating Transmission Times Suppose you have a document that contains 100,000 words, and you want to know how long it will take to transfer over a phone line using a 33.6Kbps modem. Protocols Computers can convert information into different forms, so that it can be transferred over different kinds of wiring systems. To ensure that systems created by different manufacturers can communicate with each other, engineering standards called protocols are observed. Physical protocols control how information is sent over physical media like copper wire or fiber optic cabling.
Logical protocols control how information is packaged and addressed for use by applications.
Physical and logical protocols are usually used in conjunction with each other. Ethernet is a physical protocol. Defining Ethernet Technology Ethernet cards transfer computer data more quickly than telephone modems. Instead of trying to carry data over a connection that was intended to carry the human voice, an Ethernet connection is designed to make the most efficient possible use of the wiring and system to carry computer data. The term Ethernet refers to computer communications devices that operate according to the guidelines contained in IEEE802.3, an industry standard that ensures that equipment from different manufacturers can interoperate.