In response to the closed topic:
http://forum.mikrotik.com/viewtopic.php ... &sk=t&sd=a

I would like to post the following solution / explanation for the problem that has been discussed at length. After wrestling with this issue for over a year and reading every post I could find on the topic, I am happy to finally report a solution to the client re-association problem.

We saw this problem develop shortly after replacing a Prism based card in our AP with an SR2 and cutting all clients over to a WPA security configuration with a virtual AP for non-WPA clients. Initially, we had Tranzeo (non-WPA) units mixed with Mikrotik / Atheros gear. We first replaced all gear with Mikrotik boards and Atheros based client radios and removed the virtual AP so that all clients connected via WPA. After this, the association problem persisted and the ACK values seemed way out of whack. We experienced all of the symptoms described in the thread referenced above including poor quality of service, having to disable / re-enable the card to get clients to connect, sometimes only seeing a handful of clients connect, but no traffic passed, etc.

We have determined that this issue is isolated and caused when Ubiquiti SR2 cards are used as Access Points. After trying 4 - 5 different SR2 cards, 2 different antennas and antenna cables, different POE injectors, and 3 different Routerboards in a troublesome Access point, we finally swapped the SR2 out for a Senao 8602+ card and the re-association problem cleared up completely and immediately. Clients immediately connect (as expected) and the ACK values are looking as they should. Traffic is being passed efficiently and there is no degradation of service as before. We have 17 clients on this sector.

The problem here is either something fundamental with the SR2 card itself, or with the drivers that are used on RouterOS for the SR2 as an AP. Only Mikrotik or Ubiquity could shed more light on the issue at this point.

Other scenarios that we were not able to test in our process:

(1) SR2 Access Point in Combination with WPA
(2) SR2 Access Point in Combination with mixed version of Atheros based cards
(3) SR2 Access Point running NSTREME (we did not test if this would solve the re-association issue)
(4) Other contributing factors that I am no thinking of...

All this said, we saw the issue develop, then went through a lengthy process of debugging and troubleshooting, and finally saw the issue go away when swapping out the SR2 for the 8602+ card. Like all of you, we tried every conceivable configuration of the SR2 access point in an attempt to get reliable service. At the end with the SR2, we were able to achieve adequate service for periods of time, but would experience seemingly random variations of the symptoms from time to time and always when the SR2 AP would reboot. The 8602+ has completely cleared the issue up and provided the needed insight on this problem to intelligently avoid it in the future.

This issue was experienced with the 8602+, R52 and a bunch of other Atheros based cards. Not trying to rain on your parade but if swapping out the radios with 8602's would have corrected the problem we'd all have done that by now.

Unfortunately our problem that developed with a CM9 card, where clients
wouldnt associate, but WDS would was solved by replacing it with an SR2, with
some 25-30 clients now associated.

We havent tested further the CM9 card, to detirmine any subtle failure mode
as it ceased stable associations during a storm, but there didnt appear to be
anything wrong with the recieve sensitivity on a 5km WDS connection.

I believe that these disassociation events are caused by something external
initially, possibly a bad client or someone playing with sniffing or WEP cracking
software. Then as clients drop off, there is some sort of race condition that
can develop in the PPPOE server say due to flooding of radius authorisation
requests.. WDS lines never seem to go do, so its a layer 3 thing..

This issue was experienced with the 8602+, R52 and a bunch of other Atheros based cards. Not trying to rain on your parade but if swapping out the radios with 8602's would have corrected the problem we'd all have done that by now.

I agree, nothing new! Sorry. Too generalized. When we tried the 8602 it did solve, but also never picked up any of the far clients. So, it actually doesn't solve!