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Forum Replies

  1. Hi Rene, could you describe using your simply language, for what we need option 82?

  2. Hi Yevgeniy,

    DHCP Option 82 stands for “DHCP Relay Agent Information Option”. If you haven’t seen how DHCP relay works before, take a look at this lesson:


    Option 82 was originally created for really large (WAN) networks where we have a lot of DHCP relays and central DHCP servers. The idea behind it is that the DHCP relay can add extra information which the DHCP server can use to decide which pool to use for assigning an IP address. Option 82 has a “Circuit ID” and a “Remote ID”

    ... Continue reading in our forum

  3. Zaman,
    IOS XE is a different from the “traditional” IOS operating system in terms of its architecture. IOS XE still runs the traditional IOS, but it runs as a single process (daemon) within a larger linux operating system. Notice in your output, there is an indication of this (linux):


    So, “Version 03.12.00a.S” refers to the large linux operating system, while “Version 15.4(2)S0a” refers to the IOS version being run by the IOS daemon within IOS XE. Make sense?

    Here’s some more info on IOS XE if you want to read about the new

    ... Continue reading in our forum

  4. Hello Manuel

    Rene describes what option 82 does in this post very well.

    As to why you should disable option 82, when DHCP snooping is enabled on a switch, option 82 is enabled by default. That is, any DHCP request packets that are sent from a host will enter the switch and will have option 82 information ADDED to the request before it is sent on to the DHCP server. Specifically, enabling DHCP snooping on the switch adds the giaddr value of in the DHCP packet. However, the DHCP server is expecting this field to be set to that of the relay agent (a non

    ... Continue reading in our forum

  5. Hello Harry

    When you post a question, try to find a thread that is close to the topic that you are asking about. This is the perfect thread for this question. However, if you find that there is no thread that matches your question, you can always post a new topic, and we may re-categorize it into the appropriate thread.

    As for your question, keep in mind that the IP helper address command installed on the local router will just take any DHCP request that it hears on the network and forward it to the DHCP server that exists on a different subnet. This does no

    ... Continue reading in our forum

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