DHCP Option 82 and switches


We have moved to Option 82 on all of our wireless subscribers. Works great with Sonar and Mikrotik. We are struggling for a similar solution for our MDUs. What are you all doing that use option 82 and have MDUs where a router is connected to a switch (or a number of switches) at the layer 2 or 3? I see Option 82 as an option in our TP-Link switches but when we turn it on, we are not getting the results we expected. How do a allow a MDU subscriber to change their router but have it still authorize with us (without RADIUS or PPPOE)? Got to believe Option 82 is an option…


@Chad_Wachs have you found any options?


No, but we really need to… Each new MDU reminds us…


Are you using Option 82 with Ubiquity radios in bridge mode?


Cambium ePMP. No Ubiquiti radios.


We are getting much closer to a working solution with Option 82 and Mikrotik. We are working perfectly now with CCRs. If there are no switches in line and customers plug directly into a CCR port, we simply turn on option 82 in the router and set the physical port name to a unique dummy MAC like 2E-1E-02-00-00-01. That unique MAC is passed along as the Agent Remote ID to the batcher. We then assign an inventory item to the customer with that MAC and anything they plug in to that port gets assigned to them via the batcher and option 82.

Well, now we buy a Mikrtotik CSS326 switch. It has option 82. We think we’ll try the very same solution that works on their routers and name each port with a unique dummy MAC. I type in 2E-1E-02-00-00-01 and hit save. It truncates it to: 2E-1E-02-00-00-0 which is clearly not a valid MAC address and never triggers an option 82 lease in Sonar.

What we really need is the ability to add devices to inventory with "MAC address " that is not a MAC address. Let me add inventory to a customer with a MAC of “123-Main-eth11” or something like that. Now, I can name a port something that makes sense, it gets passed along as an Agent Remote ID and Sonar sees it as inventory even though it is not a real MAC address.

Is this possible today? Is it possible in v2? Is there a way to do this at all? Using non-MAC strings in a Agent Remote ID is very common in the industry but how do I get that into Sonar to work?

Example of a DHCP lease in a Mikrotik using a CSS Mikrotik switch. Will this work with no “-” or “:” in the string? We don’t have this test device online…


Well, to answer my previous post, if you put 4E1E02000001 as a port name in a Mikrotik switch, Sonar will automatically translate that to a MAC address and option 82 works.

I would still love the ability to use non MAC strings in Sonar for inventory items to make Option 82 and Agent Remote IDs work a little nicer…


It’s on the list to investigate at some point, I’m not sure how we’re going to do it yet.