Understanding Switches


  • Level: Beginner
  • Presenter: Eli the Computer Guy
  • Date Created: July 12, 2010
  • Length of Class: 57 Minutes



Purpose of Class

  • This class discusses the purpose of network switches and their functions.

Topics Covered

  • Switches vs. Hubs
  • Managed vs. Unmanaged Switches
  • Speeds and Duplex
  • Quality of Service
  • Power Over Ethernet
  • VLAN
  • Spanning Tree Protocol

Class Notes

  1. Basic Switch Concepts
    1. A hub simply splits the Ethernet signal like a cable splitter
    2. Broadcast storms happen when too many computers are trying to talk at once
    3. Switches allow multiple computers to be able to talk at the same time.
    4. Switches are OSI Model layer 2 devices and use network devices MAC Addresses for identification
  2. Managed vs. Unmanaged Switches
    1. Unmanaged switches are completely automatic
    2. Managed switches can be configured
  3. Speed
    1. Speeds – 10Mbps / 100Mbps / 1000Mbps
    2. Full Duplex means a device can send and receive traffic at the same time
    3. Half Duplex means a device can either receive or transmit traffic
    4. Backplane determines how much total data a switch can handle
  4. Trunk Connection allow multiple switches to be tied together
  5. VLANs are separate LANs on the same switch
  6. POE – Power Over Ethernet allows you to power network devices using cat5 cable
  7. QOS/ COS – allows you to prioritize network packets so that real time communication is not interrupted by file transfers.
  8. Spanning Tree Protocol is a networking protocol that helps prevent network loops


Eli the Computer Guy (2030 Posts)

Eli the Computer Guy has 16 years experience in technology being the guy to fix "it". From the Army, to building out new satellite offices for the enterprise, to running his own shop with 9 full time employees Eli has real world experience with almost all systems that technicians will be working with. Eli has 1600 hours of formal technical beyond his Bachelors Degree in Criminal Justice on technologies ranging from Avaya PBX/ Audix to Microsoft, Red Hat Linux, MySQL, Cisco and much more.

22 Responses to Understanding Switches

  • Stanley says:

    Hi again Eli!
    Knowing that two devices in different VLANs cannot communicate directly with each other unless the two VLANs are connected to a router, is it possible for the devices on the different VLANs on a switch to use the trunk ports to connect to other switches?
    If it is possible, how will traffic be handled along the trunk to prevent collision of signals from devices of different VLANs?

  • Eli the Computer Guy says:

    If you’re using a Cisco Switch, or other high end switch, you can separate traffic into VLANs on the Trunk ports

  • Kojo says:

    Please dont you have a video on :”understanding routers”?

  • Xavier says:

    Well done Eli. I must have to say that you gave me a wonderful Christmas gift by posting this videos. I have to thank you. I know you are a busy man and doing these videos are time consuming. All the books I read about switches are useless in comparison with your well presented video.

  • Furqan Ahmed Khan says:

    Thankyou very much for a great lecture
    my name is furqan ahmed khan from Pakistan where educational department is not is in good progress, these type of lectures help us a lot
    THANKYOU very mush Sir.

  • Jose says:

    Eli Thanks for your explanation, nice video

  • parvej alam says:

    hey man….really u r doing the nice job….god bless u…

  • prasad says:

    Nice video sir you are great

  • Okoro Ikedich says:

    this is awesome, i’m preparing for my CCNP switch Exam by july and this has helped me to comprehend the basic concept of a typical network switch, thaks alot sir, u r good

  • Bart says:


    Thanks for the video, very informative. Just a quick question: you have mentioned that if you dont have switch you dont have a network…got me little bit confused. Now, all routers comes with 4+ ports that acts like a switch(i think) so if you running something small like 4-10 pcs via lan and wlan would you really need a switch? My question would be: when you would really need a switch besides having more physical equipment connected to the same network?

    Thank you in advance,

  • raghu says:

    superb trainig love uuuuuuuuuuuuuuuuuuuuuu

  • billy says:

    thanks. and still dont get the differences between router and switch… can you please tell me about it. is it both that splits the internet to multiple users or one of them?… please explain it to me.. and thanks.

  • agent says:

    simply awesome

  • Nagakrishna says:

    is swtich a layer 2 device…??

  • Eli the Computer Guy says:


  • tarek says:

    Dear Elli,
    a big thanks from bangladesh for such a helpful lecture… thanks…

  • Chris says:

    Thanks Eli,

    So much I’ve seen over the years but never knew the cause or how to explain has been resolved because of your videos.

    This is awesome!

  • Gary says:

    By far the best down to earth videos out there!

  • harish says:

    Thanks Eli,
    Nice tutorial

  • harish says:

    Thanks Eli,

    Thanks for the video, very informative

  • Kenneth says:

    lol i saw a bunch of old half duplex equipment while i was satcom tech in the usaf… you didnt see any when you were in the army?

  • Kenneth says:

    so can you daisy chain trunk ports so you’d have like 10 or 20 switches just linked up or does that overload the network?

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