Preferred AP List - functionality details

I'm curious to see how this works if it can see more than one AP.

In my deployment I'm doing ABAB frequency reuse with 90* sectors NSWE.  I'll be using my naming scheme tower-ap1, tower-ap2, tower-ap3, tower-ap4.

If I put all four SSIDs in the ePMP SM and it can see both ap1 and ap2, how will it decide which to connect to?  Will it ever change to a different SSID based on the AP statistics?


The 2.3 user guide didn't have any details on how this list works.

Hi Josh, 

The SM chooses an AP based on the highest RSSI and CINR values. In your example you have all four APs in the Preferred List. So first off all, the SM will never connect to an AP that's not in the preferred list (unless its empty). The SM will first scan all the channels in the scan list, record the SSIDs, RSSI and CINR value of all the APs that it sees. It will then choose the AP with the best RSSI value. If it sees two or more APs with the same or similar RSSI values, then it will pick the AP with the best CINR. If all things happen to be equal, then the third criteria is the channel bandwidth. The SM will pick the AP with the widest channel bandwidth (throughput biased). If that is also equal across the APs, then it picks the AP with the lowest BSSID. 

Once an SM picks an AP and connects to it, it will not periodicially rescan for a better AP until it is disconnected. This is a pending feature still to be implemented. 

Hope that helps. 

Thanks,

Sriram

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Hi,

have you implemented the feature that allow the SM to rescan periodically to connect with the AP with best signal?

This is a usefull feature.

Thanks in advance.

also it would be nice to have it pick prefered based on mac address, if its prefered mac isn't around then grab an alt. AP...   the idea of having all APs the same SSID the same to make the field work shorter is always nice.   jump up, check lights and call teir 1 for alignment.    

currently we do have all APs set to the same SSID so if one drops, the customers can move to an alt for the time being.  being able to rescan after say 30 minutes for its prefered AP would be handy as well as seletecting the primary via MAC as well.    we use a lot of contractors when we get slammed and the simply see lights and hookup method saves a lot of time.   (we set the ethernet mac address as the name of the device as the hostname to have tier 1 support grab it fast)

probably the only thing i liked about UBNT gear actually works with this respect,

we use a management VLAN to ping the watch dog through, if it moves to a new AP, it ended up in a new subnet which caused the management watchdog ping to fail, after 15 minutes, the unit would reboot.

the customers data vlan is the same on all APs, only the management LANs change tripping a reboot.

downside, that only works in bride mode, in router mode it finds its way throught the customers data vlan, and ubnt gear you cant control the number of macs LAN side, which makes that a two sided tool.  

overall the selection method in cambium works well, but I'd love to see just a little extra added to it :)


@vrega wrote:

Hi,

have you implemented the feature that allow the SM to rescan periodically to connect with the AP with best signal?

This is a usefull feature.

Thanks in advance.


Hi - Not yet but this is in progress. We'll let you know as soon as we have a target release. 

Thanks,
Sriram


@Chris_Bay wrote:

also it would be nice to have it pick prefered based on mac address, if its prefered mac isn't around then grab an alt. AP...   the idea of having all APs the same SSID the same to make the field work shorter is always nice.   jump up, check lights and call teir 1 for alignment.    

currently we do have all APs set to the same SSID so if one drops, the customers can move to an alt for the time being.  being able to rescan after say 30 minutes for its prefered AP would be handy as well as seletecting the primary via MAC as well.    we use a lot of contractors when we get slammed and the simply see lights and hookup method saves a lot of time.   (we set the ethernet mac address as the name of the device as the hostname to have tier 1 support grab it fast)


Hi Chris, 

rescan after a certain time period is something we're working on. I'll keep you posted as soon as we have a target release. 

MAC based selection is an interesting idea. Something we'll look into. 

Thanks,

Sriram


@Chris_Bay wrote:

probably the only thing i liked about UBNT gear actually works with this respect,

we use a management VLAN to ping the watch dog through, if it moves to a new AP, it ended up in a new subnet which caused the management watchdog ping to fail, after 15 minutes, the unit would reboot.

the customers data vlan is the same on all APs, only the management LANs change tripping a reboot.

downside, that only works in bride mode, in router mode it finds its way throught the customers data vlan, and ubnt gear you cant control the number of macs LAN side, which makes that a two sided tool.  

overall the selection method in cambium works well, but I'd love to see just a little extra added to it :)


Hi Chris, 

With the ability to rescan after a period of time to come to the primary AP, this mechanism of pinging the SM to see if its on a specific subnet will no longer be needed, correct? Let me know if I have misunderstood you. 

Thanks,

Sriram

Yes sir! If they rescan after a period of time that would replace the watch dog rig we put in place for the ubnt gear.

I like the idea of a preferred MAC address as we also use a common said for all access point to simplify the install process but the only downfall is if you have a failure of an access point you will need to reconfigure all the subscribers again with the new MAC address.

Why not set the priority to SSID and the device name or some other unique identifier that can be set in the GUI of the access point.

Looks like this promised functionality didn’t eventuate, 6 years later?

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Pretty sure it doesn’t " chooses an AP based on the highest RSSI and CINR values." it connects to the AP that is first on the list, if it doesn’t see that one it connects to the one second on the list etc… etc…