Introduction
This article is based on this specific issue with apple ios clients (ipads with iOS 6.1.3 in my case).Client shows connected to two wlans/ssids, underlying here is BSSID mac overlap. BSSID Mac Overlap issue with Apple iOS dual band clients
Problem
Dual band Apple clients running 6.1.3 (perhaps other flavours as well) behaves incorrectly and shows connected/associated to two wlans on CUWN.
What Exactly Can we see on this Client
(Check mark against the two wlans signifies association)
How can we verify Bssid Mac overlap?
1. Identify the wap this client is associated with.
2. Issue following commands on the wlc cli,
config paging disable
sh ap wlan 802.11a/802.11b <ap name>
Sample outputs
sh ap wlan 802.11a 10-2a-ap2109
Site Name........................................ default-group
Site Description................................. <none>
WLAN ID Interface BSSID
------- ----------- --------------------------
1 umd 00:26:cb:4c:a0:7f
3 umd 00:26:cb:4c:a0:7d
4 umd 00:26:cb:4c:a0:7c
5 umd-secure 00:26:cb:4c:a0:7b
6 umd-voip 00:26:cb:4c:a0:7a
7 umd-dev 00:26:cb:4c:a0:79
9 ip6 00:26:cb:4c:a0:77
10 umd 00:26:cb:4c:a0:76
11 umd-secure 00:26:cb:4c:a0:75
sh ap wlan 802.11b 10-2a-ap2109
Site Name........................................ default-group
Site Description................................. <none>
WLAN ID Interface BSSID
------- ----------- --------------------------
1 umd 00:26:cb:4c:a0:70
3 umd 00:26:cb:4c:a0:72
6 umd-voip 00:26:cb:4c:a0:75
7 umd-dev 00:26:cb:4c:a0:76
9 ip6 00:26:cb:4c:a0:78
10 umd 00:26:cb:4c:a0:79
11 umd-secure 00:26:cb:4c:a0:7a
(The concerned wlan ids in our case and the overlapping bssid mac is highlighted as above, wlan id 7 and 10)
Note1# For 802.11a Bssid mac starts with last hexadecimal F and continue to go down. For 802.11b it starts with last hexadecimal 0 and continues to go up.
Note2# Generally you can see this issue when there are large number of wlans being serviced by the acces point. But that in no means an absolute necessity for this problem to occur.
Workarounds Feasible
1. Have wlan serviced on only 802.11a/n or 802.11b/g/n.
2. Reduce the number of wlans being served on the AP.
3. Renumber the wlans.
CSCud88177 Apple iOS clients report two associated wlans with bssid mac overlap
Resolution
1. Employ workarounds as above.