I’m a fan of antennas. They’re pretty awesome components of Wi-Fi networks and I think they’re one of the most under-appreciated and oft-overlooked components, so when someone introduces a new antenna related technology, I tend to sit up and take notice!
Recently, Meraki released their new external antenna model APs, the MR42E and MR53E. In the past, if you needed antenna flexibility in a Meraki solution, you had to use their outdoor rated AP. This introduction, in addition to rounding out their AP portfolio, snuck a new innovation into the market that Meraki has dubbed ‘Smart Antennas’. With the promise of auto-identifying an antenna to the AP, I couldn’t not know more about it! One of the more notable aspects of using external antennas is the potential risk to exceed regulatory compliance. While not terribly complex, the risks for getting it wrong could see the Feds breathing down your back – and nobody wants that! In addition to self-identification for compliance reasons, the new models of APs include more connectors than one might otherwise expect – 5 connectors for the MR42E, and 6 for the MR53E! This breaks down to 3 Wi-Fi antennas, 1 security/scan antenna, and 1 BLE/IoT antennas for the MR42E, and the same compliment on the MR53E with one more Wi-Fi antenna to support that 4th spatial stream. Without delving into each individual component, I really wanted to get a feel for if this thing did what it promised it would do, so I hooked them all up to their respective ports:
That’s a lot of cables!
Fired up the AP, claimed the hardware in my dashboard account and went poking on the antenna settings! Sure enough, where you would normally define an antenna, the exact model number of the antenna array I had was shown!
The cloud got it right!
Hoping it wasn’t fluke of some sort, I powered off the AP, disconnected them all, and tried again. Sure enough, this time, the dashboard presented me with the expected drop down list of available antennas.
The cloud still wants to help out.
I was impressed, it was magic, it worked automatically and wonderfully – and I had to know how. One screwdriver later (the tool, not the drink), I had done the unthinkable, and performed the ill-advised dissection of the shiny new antenna looking for something out of place:
No stranger to the inside of an antenna, the culprit jumped out at me pretty readily:
What appears to be a Maxim Integrated DS2431 1-wire EEPROM was sitting inline just before an antenna element. I traced it back to the connector and found it belonged to the externally-labeled IoT connector:
So, I dutifully connected just the IoT port to the AP, fired it up and viola! The dashboard indicated that the antenna was identified properly despite the fact that only 1 of the 6 connections was attached. This seems to reinforce that Meraki has indeed found a pretty intuitive way to integrate a digital component onto an analog line (as opposed to Cisco that has actual digital connectors in the DART) for a one-time polling of the antenna ID. This was further reinforced by booting the AP without the IoT port connected (so it did not identify the antenna correctly) and then re-attaching it without powering down the AP. After a day of uptime, the AP never properly re-identified it’s antenna. This means that, if you’re using the Meraki smart antenna solution:
- Make sure that the antenna cables are attached to the proper port using the silkscreen indicator on the RP-TNC connectors
- Make sure that if you change any antenna ports (especially the IoT port), you should reboot the AP so it can properly identify itself to the AP, and subsequently the cloud
It remains to be seen what kind of ecosystem Meraki intends to develop with 3rd party antenna developers, but rest assured, if you want to use a 3rd party antenna today on these new Meraki APs, you certainly can – you just need to log into the dashboard and make sure you pick the equivalent Meraki antenna that closest matches the gain of your 3rd party antenna.
from
https://sc-wifi.com/2018/04/06/meraki-gets-smart/
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