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DHCP Snooping not working correctly, why?

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  • 1.  DHCP Snooping not working correctly, why?

    Posted Jul 06, 2026 03:25 AM

    Hi, 

    we had DHCP-Snooping enabled in our Network for a while now and so far we didnt notice any Problems.
    i configured that via central but i doubt the switches ned it for the actual task, so that shouldnt matter here.

    This is the config that runs on all of our Switches:
    And today we had a problem with one client acting as a new DHCP server on 192.168.0.1 that this particular switch seemingly ignored?

    this is the device i found via wireshark and i traced it back via mac to this Port here:


    which, as you see, should be in the untrusted Port Range of 1-48.

    so why was this MAC even allowed to send DHCP here? as far as i see it, it shoudlve been stopped right at that switch for being on the wrong port AND being not an authorized Server.



  • 2.  RE: DHCP Snooping not working correctly, why?

    Posted Jul 16, 2026 11:10 AM

    hi,

    i guess u need to activate it on the vlans , that you want to protect with dhcp-snooping: dhcp-snooping vlan <vlan-id>

    hth