Physical Layer Devices : Hub and Repeater

Hub and repeater are the two physical layer network devices that facilitate the communication at physical level.

Hub

All networks required a Centre location to bring media segments (i.e computer) together this central locations are called HUB.

  • Hub Is a multiport repeater.
  • Hub is a physical layer device.
  •  Generally used to connect computers in a LAN.
Hub and Repeater

 

There are three categories of Hub:
 
1) Passive Hub:

Passive hub simply combines the signal of network segments .There is no signal processing of regeneration, because it does not Boost the signal and, in fact, absorb sum of the signal. also, with a passive hub, each computer received the signal send from all other computer connected to hub.

2)Active hub:

Active hub except that they have electronic component that regenerates or amplifier signals. Because of this the distance between device can be increase.
They are also much more expensive then Passive.

 

3) Intelligent Hub:

In addition to signal regeneration intelligent hub perform some network management and intelligent path selection many switching Hub choose which alternative path will be the quickest and send the signal that way.

Repeater:

 

Due to the properties of medium and other reasons, the signal gets weak when it travels long distance weaking of signal limits the distance any medium can carry the data. Adding a device that amplifies the signal can allow it to travel further increase the size of the network.

The device that amplifies signals in the way in this way are called repeaters.

Repeater is a physical layer device

Hub and Repeater

Repeaters Falls into two categories:

  1. Amplifier repeater.
  2. Signal regeneration repeater.
 
1) Amplifier repeater:

 simply amplifier the entire incoming signal that is the amplifier both the signal and noise.

 

2) Single regenerating repeater:

Signal regenerating repeater differentiate between data and noise and retransmitting only the Desire information this reduce the noise

 

Hub and Repeater is a Physical Layer devices.