Controller Based WLANs

Q:

ADP is Aruba Discovery Protocol which helps the AP discover the master controller. Will it help AP find the master if the AP is in Aruba L-2 vlan?

Aruba Discover protocol works on a L-2 Multicast or L-3 Broadcast:

Protocol                                     : UDP 8200

L-2 multicast IP address         : 239.0.82.11

L3 Broadcast IP address         : 255.255.255.255

We can see the multicast ADP traffic from the datapath session table for multicast address 239.0.82.11:

 #show datapath session table 239.0.82.11

Source IP       Destination IP  Prot SPort DPort  Cntr    Prio ToS Age Destination TAge Packets    Bytes      Flags          

--------------- --------------- ---- ----- ----- -------- ---- --- --- ----------- ---- ---------  --------- ---------------

10.10.12.135    239.0.82.11     17   49152 8200   0/0     0    0   0   0/0/0       b    23         920        FC             

10.10.11.43     239.0.82.11     17   49152 8200   0/0     0    0   0   0/0/0       b    23         920        FC             

10.10.11.67     239.0.82.11     17   49152 8200   0/0     0    0   1   0/0/0       4f   120        4800       FC             

10.10.11.85     239.0.82.11     17   49739 8200   0/0     0    0   0   0/0/0       35   105        4200       FC         

We can see the broadcast ADP traffic from APs datapath table:

(Aruba7210) #show datapath session table  10.10.11.70
 Source IP      Destination      IP Prot SPort DPort Cntr Prio ToS Age Destination TAge Packets Bytes Flags 
--------------- --------------- ---- ----- ----- -------- ---- --- --- ----------- ---- --------- --------- --------------- 
10.10.11.70     255.255.255.255 17   49152 8200   0/0     0    0   1   0/0/0       42   120        4800       FC              
10.10.11.70     239.0.82.11     17   49152 8200   0/0     0    0   1   0/0/0       42   120        4800       FC              
255.255.255.255 10.10.11.70     17   8200  49152  0/0     0    0   4   0/0/0       42   0          0          FY   

We can see the ADP Recieved and transmitted messages:

(master) #show adp counters
ADP Counters
------------
key           value
---           -----
IGMP Join Tx  1
IGMP Drop Tx  0
ADP Tx        6
ADP Rx        6

We can see the ADP configuration using:

(master) #show adp config
ADP Configuration
-----------------
key        value
---        -----
discovery  enable
igmp-join  enable
igmp-vlan  0

A controller will only reply to a received ADP query if ADP is enabled and It is a L-3 Vlan. If the AP is connected to L-2 Vlan on the controller, controller will not send back ADP reply and AP may not find the master using ADP.