Understanding how VLANs function

veritas_libertasveritas_libertas CISSP, GIAC x5, CompTIA x5Greenville, SC USAPosts: 5,735Member ■■■■■■■■■■
Hello Everyone,

I am studying for Security+ certification. I hoping to knock it off next month :) I just finished my first book 500 pages, and have already begun going through my ExamCram book.

I learned about VLANs before but still feel like I am missing something. Now VLANS are used for Security and limiting Broadcast Domains correct? Does it do so by limiting the broadcast to only ports/users that are in the VLAN? Does it do so by tagging the packets? Am I completely off? icon_confused.gif:
Currently working on: Linux and Python

Comments

  • msbachmanmsbachman Posts: 43Member ■■□□□□□□□□
    It has something to do with vlan trunking protocol. Others would be able to help out in more detail, just thought I'd throw in my two cents.

    Note: I reread through your question and I think I'm a bit off, but I'm posting this in case it could be of some use whatsoever.
  • Bl8ckr0uterBl8ckr0uter Posts: 5,031Inactive Imported Users ■■■■■■■■□□
    Hello Everyone,

    I am studying for Security+ certification. I hoping to knock it off next month :) I just finished my first book 500 pages, and have already begun going through my ExamCram book.

    I learned about VLANs before but still feel like I am missing something. Now VLANS are used for Security and limiting Broadcast Domains correct? Does it do so by limiting the broadcast to only ports/users that are in the VLAN? Does it do so by tagging the packets? Am I completely off? icon_confused.gif:

    Think of a Vlan as a "Virtual-Lan". How do Broadcast work in normal circumstances? They go through out the network until they are stop by some sort of layer 3 device. With vlans it is essentially , broadcast go through out the "lan" and that lan, can consist of 1 port on a switch or 1 port on 10 seperate switches and the process is essentually the same. VTP does tag the packets I believe and injects the header of the packet with Vlan information.

    Security? Hmm idk..maybe they mean like how you can assign certian users (computers) certian access based upon there switch port. I could be wrong but i bet that is what they mean.

    Here is some info from cisco's mouth (way better than I could put iticon_wink.gif)

    Understanding VLAN Trunk Protocol (VTP) - Cisco Systems
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