I recommend you use different MACs on Ethernet devices that are connected to other Ethernet devices. Especially if they are all on the same collision domain.
Improper operation may result in having both devices use the same MAC. Of course this will continue to be a problem until MAC-V6 is widely implemented, but try to find different MACs. I know they are hard to come by, but it is sure to make you life easier... (I used to have a block of MACs assigned to my company. Not sure if I had to pay Xerox for them or what. Been a long time ago.) From: That One Guy via Af Sent: Thursday, November 13, 2014 11:48 AM To: [email protected] Subject: Re: [AFMUG] For love of all that is evil (mikrotik/routerboard) I always wondered how manufactures reuse their MACs, apparently all in the same batch On Thu, Nov 13, 2014 at 12:35 PM, Sterling Jacobson via Af <[email protected]> wrote: Freaking hell, I just spent 30 minutes trying to unravel a router mystery. Ended up that both of my CCR Mikrotik routers had THE SAME MAC ADDRESSES between them! They are identical. Every port had a consecutive MAC number, but they were the same numbers for both the SFP and GigE ports across the two routers. I'm guessing they flashed them both at the manufacturer the exact same, then didn't make it through a MAC renumbering. Or is this common with Mikrotik now days? I'm sure I've encountered it before, but like once every five years. Just a FYI for all y'all who use Mikrotiks. Watch your backs (I mean MACs)! -- All parts should go together without forcing. You must remember that the parts you are reassembling were disassembled by you. Therefore, if you can't get them together again, there must be a reason. By all means, do not use a hammer. -- IBM maintenance manual, 1925
