I have a home 802.11N + ethernet router (D-link DIR-655) with MAC filtering enabled. I am trying to connect a switch to one of the ports (D-Link DGS-2208) and connect two devices to that switch.

Both devices work correctly when connected directly to the router, but don't work when the switch is in the middle. My understanding is that this should work, what am I missing? Is there a MAC address for the switch itself that I need to add to the MAC address whitelist on the router? If so, how do I find it (it's not printed on the device anywhere I can find it). Also, if that is the case, will whitelisting that MAC address allow anything connected to the switch to access the network?

  • 2
    Personally, I think you should stop wasting time with mac address filtering. It adds almost no security. Mac addresses are easy to find on the local network and trivial to forge.
    – Zoredache
    Oct 4, 2009 at 2:42
  • In general, I agree with you completely. In my particular situation though, I'm trying to protect against a not particularly savvy roomate who has physical access to the router. I need to mitigate the scenario where he just plugs a laptop into the router.
    – HardTech
    Oct 4, 2009 at 4:41

2 Answers 2


Less of an answer and more of a possible troubleshooting step: Have you tried turning off the MAC address filtering and seeing if the devices work? If so, then you know the problem is related to the filtering; if not, then you can try troubleshooting problems with GigE etc.

More directly related to your original question: I believe that all switches do have their own MAC addresses. You can often find the address printed on a label on the device itself.


Packets from those computers will be tagged with their own MAC address regardless of an intervening switch. Both of your devices are GigE, so there should be no need for a crossover cable. (Auto-MDIX is built into the GigE spec.)

The only thing I can think of is that maybe your computers are sending jumbo packets and the router doesn't understand them? (I'm not even 100% sure that makes sense.)

  • If jumbo frames were the problem, from the way the problem is described it would be the switch that isn't compatible with jumbo frames.
    – Haakon
    Oct 4, 2009 at 1:11
  • Both the switch and the router support jumbo frames. Neither device is set up to use jumbo frames.
    – HardTech
    Oct 4, 2009 at 4:38

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