Mini Howto for a simple way to block a MAC address on Extreme Network switches

September 12, 2015

Yesterday I needed to block a MAC address on an Extreme Networks switch (XOS) … sure, I could write an ACL for this but there is a better way:

To block a MAC address:

create fdbentry aa:bb:cc:dd:ee:ff vlan <VlanName> blackhole

To unblock a MAC address:

delete fdbentry aa:bb:cc:dd:ee:ff vlan <VlanName> blackhole


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  1. thanks

    Comment by Easy Live Trade — January 6, 2016 #

  2. I was able to create fdbentry but cannot use the blackhole command.

    create fdbentry 78:xx:xx:FF vlan ABCD ports 1:16 <— Ok

    create fdbentry 78:xx:xx:FF vlan ABCD ports 1:16 blackhole <— Error

    FYI, I'm doing this on x480e XOS ver 12.0.3

    Need your advice. THanks.

    Comment by Effendy — February 6, 2016 #

  3. 12.0.3 is really old, 15.x or later is current. I’m even not sure you can update the firmware in one jump from so an old version.

    Comment by robert — February 6, 2016 #

  4. Hi Effendy, use create:
    fdbentry aa:bb:cc:dd:ee:ff vlan blackhole

    Note that ports are not included.

    example: create fdbentry ac:46:fb:a0:3f:43 vlan “sales” blackhole

    Comment by Thomas — February 17, 2016 #

  5. Hi, I use this:

    create fdbentry aa:bb:cc:dd:ee:ff vlan “VLAN_NAME” blackhole

    But, extreme switch says me that blackhole word is wrong.

    %% Invalid input detected


    Comment by Jaime Baez — November 15, 2016 #

  6. Which switch and which EXOS version?

    Comment by robert — November 16, 2016 #

  7. Thanks! Worked a treat to prevent a user from connecting their personal laptop to the company LAN.

    Comment by wrx7m — February 23, 2017 #

  8. On my 5520 running EXOS 31.x:

    create fdb xx:xx… vlan “NAME” blackhole

    Comment by Frank M — March 6, 2023 #

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