Alternate Management Interface on MR Devices with Firmware MR30.x

[MK2]

Hello everyone,

does anyone here know anything about the function of the AltMgt interfaces in the firmware >MR30.x ? The support knows that it does not work, supposedly they are working on a fix.....but for almost a year now.

The whole issue is slowly becoming a show stopper.

[alemabrahao]

It’s designed to provide an alternate path for management traffic, separate from the data traffic.

https://documentation.meraki.com/Firmware_Features/Wireless_%28MR%29_Firmware_Features_Directory

[Purroy]

Hello,

To my knowledge this feature is working as expected.  I have several customers using it.  If it does not work on your environment I kindly suggest you open a support case to check what might be happening.

[MK2]

It is primarily about the RADIUS feature via the AltMgmt interface. Support has confirmed that there is a problem here and there is currently no fix.
The problem is that the requests to the RADIUS are sent via the "normal" and not the "alternative" interface.

[MK2]

After massive testing and tickets it seems this feature to be broken. Followed the advice to use DHCP at the AMI instead of static. Did factory resets but at the end, a wireshark of the attached switch port still shows the RADIUS packets to flow with the Mgmt-IP instead of the AMI-IP. 

I'm really at the end of my tether, I can't update the customer's APs and am stuck in version 28.x. Great.

[cmr]

Is your RADIUS server in the same subnet as the APs normal interface?  In that case I can see why it might be used instead of the management interface.  If it is, can you try changing the normal interface to a new subnetnamd see if that still fails?

[MK2]

No, the RADIUS is located in a different network, it's also a different network class.

MR29.7.1 is the latest version in which it works as expected, either with DHCP or static IPs on the Mgmt and AMI interface.

[MK2]

After more testing it seems the AP uses somtimes both interfaces.....red marked is the MGMT and green marked is the AMI interface. What the hell I'am doing wrong? 😞