Controller Based WLANs

Q:

How to find which GRE tunnel is used for a specific BSSID? 
 

For tunnel and split-tunnel mode SSIDs, APs establish a GRE tunnel to controller for every BSSID.  

To find which tunnel is used for a specific BSSID, 

1. Check the bss-table of the AP to find the BSSID.  
 

(FloorAccessMD_103) #show ap bss-table ap-name FloorAccessAP

fm (forward mode): T-Tunnel, S-Split, D-Decrypt Tunnel, B-Bridge (s-standard, p-persistent, b-backup, a-always), n-anyspot

cluster (cluster role): U-UAC, A-AAC, sU-Standby UAC, sA-Standby AAC

Aruba AP BSS Table
------------------
bss                ess          port  ip         phy    type  ch/EIRP/max-EIRP  cur-cl  ap name        in-t(s)  tot-t    mtu   acl-state  acl  fm  cluster  datazone
---                ---          ----  --         ---    ----  ----------------  ------  -------        -------  -----    ---   ---------  ---  --  -------  --------
40:e3:d6:8c:c8:f0  FloorAccess  N/A   10.0.0.10  a-VHT  ap    60E/23.0/23.0     0       FloorAccessAP  0        18m:22s  1578  -          73   T            no
40:e3:d6:8c:c8:e0  FloorAccess  N/A   10.0.0.10  g-HT   ap    1/25.0/25.0       0       FloorAccessAP  0        18m:22s  1578  -          73   T            no

Channel followed by "*" indicates channel selected due to unsupported configured channel.
"Spectrum" followed by "^" indicates Local Spectrum Override in effect.

Num APs:2
Num Associations:0
(FloorAccessMD_103) #

2. Check the datapath tunnel table for the specific BSSID and use the command --- "show datapath tunnel table | include #,----,<BSSID-in-Upper-Case>" to find the tunnel #.  

Example: 

(FloorAccessMD_103) #show datapath tunnel table | include #,----,40:E3:D6:8C:C8:F0
-----------------------------
 #          Source       Destination    Prt  Type  MTU   VLAN       Acls                    BSSID          Decaps     Encaps   Heartbeats Flags            EncapKBytes  DecapKBytes
------  --------------  --------------  ---  ----  ----  ---- -----------------------  ----------------- ---------- ---------- ---------- --------------- ------------- -----------
14      10.0.0.103      10.0.0.10       47   8200  1578  10   0   0    73   0    0     40:E3:D6:8C:C8:F0          0          0          0 IMASPab
(FloorAccessMD_103) #

From the tunnel table, we can find that "tunnel 14" is used for the BSSID 40:E3:D6:8C:C8:F0.