Mini Case 1 Chapter 4 Smith, Smith, and Smith

MINI CASE 1 Chapter 4

Smith, Smith, and Smith

Most network errors, occur during transmission, and are controlled by the network hardware and software. There are two categories of network errors: corrupted data (data that have been changed) and lost data. Networks should be designed to (1) prevent, (2) detect, and (3) correct both corrupted data and lost data. Network errors are a fact of life in data communications networks. Depending on the type of circuit, they may occur every few hours, minutes, or seconds because of noise on the lines. No network can eliminate all errors, but most errors can be prevented, detected, and corrected by proper design.

One of the biggest sources of errors is noise there are different categories but most can be limited. There are many techniques to prevent errors (or at least reduce them), depending on the situation. Shielding (protecting wires by covering them with an insulating coating) is one of the best ways. Many different types of wires and cables are available with different amounts of shielding.

* Moving cables away from sources of noise (especially power sources) can also reduce errors, this means avoiding lights and heavy machinery, locating communication cables away from power cables, and physically separating the cables from other communication cables.

* Improper multiplexing can be of concern also this can be corrected by changing multiplexing techniques (e.g., from FDM to TDM) or changing the frequencies or size of the guard bands in FDM can help.

* Poorly maintained equipment or poor connections and splices among cables is of great concern. This is particularly true for echo in fiber-optic cables, which is almost always caused by poor connections. The solution here is obvious: Tune the transmission equipment and redo the connections.

* Repeaters are commonly used on digital circuits. This may be needed depends on the amount of power lost per unit length of the transmission line. A repeater...