What is overhead - Examples and Applications

What is Overhead:

Data that is not part of the user data, but that is stored or transmitted with it. Overhead can be used for a wide variety of purposes, such as circuit monitoring, channel separation, addressing, error control, priority indication, and congestion management, in fact it is control/management information related to the user data. Although overhead is essential to the integrity of data storage and transmission, it reduces the amount of user data that can be stored or transmitted.

Example of Overhead:

The examples includes all the address related information like the source address and destination address the CRC value and the information about the port no to which the information must be transmitted all are the parts of the overhead.

Which one has more overhead, a repeater or a bridge?

A bridge has more overhead than a repeater. A bridge processes the packet at two layers; a repeater processes a frame at only one layer. A bridge needs to search a table and find the forwarding port as well as to regenerate the signal; a repeater only regenerates the signal. In other words, a bridge is also a repeater (and more); a repeater is not a bridge.

What is meant by Overhead in this Sentence?

A DS1 circuit is made up of twenty-four 8-bit channels (also known as timeslots), each channel being a 64 kbit/s (multiplexed) carrier circuit. A DS1 is full-duplex circuit, which means the circuit transmits and receives 1.544 Mbit/s concurrently.

A total of 1.536 Mbit/s of bandwidth is achieved by sampling each of the twenty-four 8-bits, 8000 times per second .With these an additional 8 kbit/s of overhead is also obtained from the placement of one framing bit that make total bandwidth of 1.544 Mbit/s.