David’s Cisco Networking Blog

Jun 27 2008   10:02PM GMT

What is the difference between a Repeater, Hub, and Switch?

David Davis David Davis Profile: David Davis

One of the junior admins at my company was studying for his Cisco CCNA. He asked me about Repeaters, Hubs, and Switches. What is the difference? Well, let’s see. A repeater does exactly that- it repeats any electrical signals that come into one port, out its other port. (there are only 2 ports on a repeater). It is a very “dumb” device (no offense to any of you repeaters out there).

Hubs are very similar to repeaters. A Hub is essentially a multiport repeater. Any electrical signal that comes into one port, goes out all other ports. Again, a very dumb device.

A repeater and a hub both work on the Physical Layer of the OSI Model.

On the other hand, you have a switch. A switch is much more intelligent. It keeps track of all Ethernet devices connected to it using their MAC address and recording what port that MAC address is connected to. Then, it intelligently uses that table (MAC Address table) to switch Ethernet frames only to the Ethernet port where that traffic is destined to go to. This saves bandwidth and PC processing power. Additionally, most switches have mangement capabilities that allow you to see what is going on, see what device is on what port, if there are any errors, and configure speed & duplex.

A switch works at the Data-Link layer of the OSI Model, Layer 2.

All of these facts are excellent to remember for your Cisco CCENT/CCNA certification.

7  Comments on this Post

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  • Abaiku
    Hi David, I was confused when I was asked the same question in a CCNA Class today, but thanks I understand better now.
    10 pointsBadges:
  • vandusharma
    Very appropriate answer. It really helps me to clear all my confusions regarding these topics.
    10 pointsBadges:
  • samar199077
    Thank you very much David. Much more info covered in this answer.
    10 pointsBadges:
  • daniel1996
    Ohhh! That is the correct answer bro.
    10 pointsBadges:
  • ahmedbile
    Hi man, thanks for this. But I have a question: What is different between hub and repeater?
    10 pointsBadges:
  • FredFlinstone
    I know this sounds arrogant/douchy, but if he is asking the difference between a repeater/hub/switch then he might want to study for CCENT first, get the certification, THEN study for the 200-105 CCNA exam.

    From my experience, if you don't understand those core concepts you will fail the CCNA exam, especially if he is taking CCNAX (accelerated) which is absurdly difficult, even for experienced network associates.

    Again, I know I sound like a douche, but trust me. I barely got these certs recently and I know from experience. All my classmates that failed were the ones that never truly understood the difference between a switch and a router.
    10 pointsBadges:
  • Mofope
    Thanks man
    10 pointsBadges:

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