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Posts: 8
Registered: ‎09-26-2017

Re: LAPAC2600 - iOS connectivity issues

We do still encounter the issue and have meanwhile upgraded to V1.0.04.001 as well.

 

According to what we were able to see from the device lists, it seems that the handover to another cluster node is somehow problematic. A device can be stuck at AP1 (from the AP point of view), but the device itself already tries to talk to AP2. But AP2 rejects that approach, as it thinks AP1 is responsible.

 

We have not fully proven that observation yet. To do so, we are currently prepared to gather the following logs:

 

- Network Trace on all APs for the affected SSID

- Network Trace on the Radius server

- Syslog Server logs (not very much outcome, but requested by Linksys support)

- Device Logs (if available, e.g. with iOS WiFi Debugging Profile)

- Diagnostic Download from all APs

 

Once we got managed to log all of this at the same time and have an affected device, we will continue chasing Linksys support Smiley Happy 

 

I'ld be great if you would create a dedicated case to probably put more pressure on this. I would be heavily interested in any outcome Smiley Happy

 

Best regards

Posts: 8
Registered: ‎01-22-2018

Re: LAPAC2600 - iOS connectivity issues

Any idea how to escalate this to Linksys and actually get an engineer to look at this? We (unfortunately) have 8 of these APs now and I wish we had done some more extensive testing before committing to them.

 

I agree that the problem seems to manifest itself when switching from one AP to another.

 

While this is an intermittant kind of bug, it isn't THAT hard to reproduce. You just have to spend an hour or so on it with monitoring gear to capture what is happening. I'm more than a little annoyed that Linksys would have this bug in their flagship business AP.

 

I tried the "fix" suggested in post #2 of this thread and it did not resolve the issue. We "upgraded" from Apple Express APs. We certainly did not have any roaming or connectivity issues with the Apple Expresses. 

 

I wonder if the problem has to do with the fact the LAPAC 2600 units cannot use 802.11r between the two wifi bands (2.4 and 5 GHZ) since it treats the two bands as two different SSIDs even though they have the same name (isn't that a limitation/bug right there? They shouldn't be treated as two different SSIDs, should they?)

 

The reason I upgraded now is that our community of about 2,000 high end homesites is about to get a gigabit fiber network and I wanted to be in a position to recommend equipment for the inevitable wifi upgrades that people will be doing.

AE
Posts: 4
Registered: ‎10-17-2017

Re: LAPAC2600 - iOS connectivity issues

[ Edited ]

I had contacted tech support and they made the following recommendations, which seemed to resolve the problem. YMMV

 

 

"Please ensure that 802.11k and 802.11r are enabled and Bonjour Discovery is disabled. You may also try disabling the Cluster mode and allow the APs to use non-overlapping channels (ie. 1, 6 or 11)."

 

 

I made the changes per the techs recommendation, with the exception of enabling 802.11r because my customer had some older Apple devices that did not play well when the 802.11r (roaming) feature was enabled. So I left it disabled.

 

Since having made these changes, my customer has not had any issues with connectivity when roaming with their devices. 

 

Hoepfully this helps others resolve the problem with these APs.

 

If need be, I do have a case number for reference. DM me for the case number in case I shouldnt post it here. 

 

 

Now, if only I can figure a resolution with the other problem I am having with these APs..... But that's another thread.

AE
Posts: 4
Registered: ‎10-17-2017

Re: LAPAC2600 - iOS connectivity issues

I recommend doing a quick Google search for "iPhone 6 roaming behavior and optimization". Cisco has a good tech reference that explains how iPhones handle handoff between APs.
Hope it helps!
Posts: 8
Registered: ‎01-22-2018

Re: LAPAC2600 - iOS connectivity issues

Thanks, I'll look up that iPhone roaming note.

 

This morning I decided to do a bunch of experiments and had concluded that the problem lies with clustering. Basically, if I keep my settings the same as they were, but administer each AP separately (quite the pain with 8 APs) and not have them clustered, iOS roaming seems to work. I'll have to live with it for a few days and make sure it is stable.

 

In my setup, I want to have the same SSID for 2.4 Ghz and 5 Ghz bands, so I can't use 802.11r (seems to be a limitation of the software design of the 2600), and I did not turn off Bonjour. But so far, just without clustering, it is working. Will update later...

Posts: 8
Registered: ‎09-26-2017

Re: LAPAC2600 - iOS connectivity issues

Regarding:

"Please ensure that 802.11k and 802.11r are enabled and Bonjour Discovery is disabled. You may also try disabling the Cluster mode and allow the APs to use non-overlapping channels (ie. 1, 6 or 11)."

 

 

  • 802.11k is enabled
  • 802.11r is disabled (necessary for compatibility)
  • Bonjour Discovery is disabled
  • Cluster Mode is enabled
  • Channels are chosen manually, no channels of neighbour-APs overlap

The whole configuration has been reviewed by Linksys and was stated to be "awesome".

 

Working without Cluster Mode is not an option for us, as we plan to enable 802.11r soon. This requires the Cluster.

 

So, sadly this is no solution for us. I will keep you tuned, once we get more insight Smiley Happy

Posts: 8
Registered: ‎01-22-2018

Re: LAPAC2600 - iOS connectivity issues

The problem seems to be with cluster mode. But 802.11r does not need cluster mode. You can run with or without 802.11r with or without cluster mode - they are independent. 

 

I'm not running 802.11r, but that's because of a different limitation with the 2600. The 2600 will not allow 802.11r to be turned on for more than one SSID. And if you have the same SSID on both the 2.4 Ghz and 5 Ghz bands, the 2600 considers that TWO SSIDs. So if you want to have one SSID spanning both bands, you cannot enable 802.11r. If you're happy having separate SSIDs, one for 2.4 Ghz and one for 5 Ghz, then you'll be able to enable 802.11r for one of those SSIDs. 

 

As it turns out, I haven't had any problems so far with fast transitions between APs without running 802.11r. I've tested it with voice calls roaming around between various APs, and it holds the call. I'll do a more extensive test today. It is possible that with the latest generation iPhones and the faster processor in this 2600, that it can do fast transitions even without 802.11r.

 

I'd just like to editorilize here and say that whoever wrote the 2600 software seems to have not understood some architectural details about clustering, authentication, and 802.11r. It really does appear that with clustering, when you roam to a new AP, it checks with other APs to see if the client is already attached to other APs, and if they are, punts the new client off the new AP after it connects. But of course, it takes the old AP a while (like up to a minute) to realize that the client is no longer attached to it. I have no idea why it does this when clustering is enable. Some bizarre security check that isn't in a specification anywhere? Some idiotic manager asked that clustering add in a special security layer? 

 

Posts: 8
Registered: ‎09-26-2017

Re: LAPAC2600 - iOS connectivity issues

 But 802.11r does not need cluster mode. You can run with or without 802.11r with or without cluster mode - they are independent. 

 

That is correct, but then the first connection to an AP takes the full time, like without 802.11r. The full potential of 802.11r requires a cluster, so all APs are part of the same mobility domain and can perform the faster handshake.

Posts: 8
Registered: ‎01-22-2018

Re: LAPAC2600 - iOS connectivity issues

I did not realize that 802.11r requires the use of a cluster. It is interesting that the 2600 allow you to enable 802.11r even if you don't have clustering enabled???

 

Note that EVEN IF linksys resolves this bug with clustering, they still have a limitation in that you can't enable 802.11r across WiFi bands (2.4 Ghz and 5 Ghz) since it treats the same SSID across the two bands as two different SSIDs and it won't allow 802.11r across two "different" SSIDs (even though they are the same).

 

I just did another walking around test on a voice call. With 802.11k and WITHOUT 802.11r, the voice call never dropped, but sometimes when transitioning between one AP and another, I would get a voice drop out for a second or so. This was a test while using WiFi calling over WiFi on an iPhone X to a landline voicemail system.

Posts: 8
Registered: ‎09-26-2017

Re: LAPAC2600 - iOS connectivity issues

I did not realize that 802.11r requires the use of a cluster. It is interesting that the 2600 allow you to enable 802.11r even if you don't have clustering enabled???

Not necessarily. Once you connected to an AP (and it's mobility domain), the 2nd handshake will leverage 802.11r and is faster. So it brings a benefit, but only once you connected to all APs once and as long as your token for the mobility domain remains valid. I have to admit, that I don't know how lange they are valid. But as they can be renewed during WiFi usage, it won't be that long I think. 

 

Note that EVEN IF linksys resolves this bug with clustering, they still have a limitation in that you can't enable 802.11r across WiFi bands (2.4 Ghz and 5 Ghz) since it treats the same SSID across the two bands as two different SSIDs and it won't allow 802.11r across two "different" SSIDs (even though they are the same).

Luckily we only use 5 GHz ;-)