Lec-10: Repeaters in Computer Networks | Physical layer devices

Summary

This video explains the concept of repeaters in networking, focusing on their role in the physical layer. A repeater amplifies and regenerates weak signals, enabling them to travel further distances. Unlike amplifiers, repeaters restore signals to their original strength without increasing them. The video also highlights that repeaters do not filter signals, nor do they manage collisions, which are determined by the number of devices connected to the repeater. Overall, repeaters are simple hardware devices that extend signal reach, and the explanation is ideal for exams like UGC NET and PSU exams.

Takeaways

• 😀 A repeater is a hardware device that operates at the physical layer of the OSI model, and does not function at the data link layer where MAC addresses are used.
• 😀 The primary purpose of a repeater is to regenerate and boost weak signals, overcoming attenuation that occurs after a signal travels a certain distance (e.g., 200 meters for 10Base2).
• 😀 Unlike an amplifier, which simply amplifies a signal, a repeater regenerates the signal, restoring it to its original strength, preventing signal corruption over long distances.
• 😀 A repeater allows signals to travel further distances. For example, with a repeater, the maximum distance for a signal can be extended from 200 meters to 400 meters.
• 😀 A repeater is a two-port device, meaning it has two ports to connect two different cables and act as an intermediary for signal transmission.
• 😀 A repeater does forward signals, but it cannot filter signals. It does not have software to stop signals from being forwarded, unlike devices like routers or bridges.
• 😀 The collision domain in a network with a repeater includes all devices connected to the repeater on both sides. The number of potential collisions is equal to the total number of devices connected to the repeater.
• 😀 Repeater does not have a buffer or memory, which means that if multiple signals are sent at the same time, they will collide because the repeater can't store them temporarily.
• 😀 The purpose of a repeater is to regenerate and forward signals, not to process or filter data. It is a purely hardware-based device.
• 😀 The detailed types of repeaters, such as analog, digital, and optical repeaters, are not essential to understand for UGC NET and PSU exams. A basic understanding of the functions of repeaters is sufficient.

Q & A

What is the primary function of a repeater in networking?

The primary function of a repeater is to regenerate weak signals in a network, restoring them to their original strength to overcome signal attenuation and extend the range of transmission.

In which layer of the OSI model does a repeater operate?

A repeater operates at the physical layer of the OSI model.

What is the difference between a repeater and an amplifier?

An amplifier increases the strength of the signal but does not restore it to its original form, whereas a repeater regenerates the signal, restoring it to its original strength to avoid signal degradation.

How does a repeater extend the distance a signal can travel?

A repeater allows signals to travel beyond their normal range by regenerating them, effectively increasing the distance the signal can travel (e.g., from 200 meters to 400 meters).

What is the function of the two ports in a repeater?

A repeater is a two-port device, where one port receives the signal, and the other port transmits the regenerated signal.

Can a repeater filter signals?

No, a repeater cannot filter signals. It simply forwards all signals it receives, whereas devices like routers and bridges use software to filter traffic.

What happens if a repeater is used in a network with many devices?

The number of potential collisions in the network increases because a repeater broadcasts all signals to all connected devices, expanding the collision domain.

What is the maximum size of a collision domain when a repeater is used?

The maximum size of the collision domain in a network using a repeater is equal to the total number of devices connected to both ports of the repeater.

What type of device is a repeater considered to be?

A repeater is considered to be a hardware device, purely operating at the physical layer of the OSI model.

Is the concept of repeaters important for GATE exams?

Repeaters are not particularly important for the GATE exam, but they are relevant for exams like UGC NET and PSU exams, where understanding basic networking devices like repeaters is essential.