Controller Based WLANs

Multicast Aggregation at AP

Aruba Employee
Q:

What is Multicast Aggregation on AP and how to configure it?

 

 

 

 



A:

This feature is designed to learn mDNS/DLNA devices at AP’s network.

 

Use case for this feature - AP VLANs are not extended to the controller. In a branch scenario, where the controllers are deployed at the Data center and APs at the branch office, and there are wired AirGroup devices in AP’s local network (VLAN) and that VLAN is not extended to the controller. In this case, Controller will not learn about these wired AirGroup devices.

With iOS8.0, Apple has introduced mDNS service discovery over Bluetooth and media streaming over P2P Wi-Fi. This breaks AirGroup AirPlay functionality. To work around to this, it is recommended to Wire the Apple TVs and disable Bluetooth. mDNS aggregation feature becomes very helpful in this scenario where Apple TVs are wired. 

 

  • Enables mDNS/DLNA devices in AP’s network are learnt at the controller
  • AP aggregates mDNS/SSDP packets it receives from its VLANs and forwards it to the controller through a GRE tunnel   
  • Useful for deployments where mDNS/SSDP device is connected to a switch and is part of a VLAN which is not trunked in the controller
  • Enables wired mDNS/SSDP devices which are not directly connected to controller or not trunked in the controller to be discovered through mDNS/SSDP messages 

 

Feature operations:

  • Tunnel is created between AP and controller when AirGroup and AP multicast aggregation configurations are enabled 
  • If there are multiple APs in the same VLAN, a leader AP is elected for each VLAN that performs multicast aggregation
  • Different use cases how AP forms the tunnel on what VLANs -
  • AP uplink VLAN is used for tunnel if provisioned else Native VLAN is used
  • In case of AP uplink is a trunk port (no uplink VLAN is configured), multicast aggregation happens on the Native VLAN
  • If AP uplink is a trunk port with native vlan as x and allowed vlans as x,y,z and ‘uplink-vlan’ configured as vlan y for AP, then multicast aggregation happens on VLAN y 
  • AP creates a GRE tunnel to send mDNS/DLNA packets to the controller.
  • In case of multiple APs in the same VLAN, a leader AP in that VLAN is selected to which sends mDNS/DLNA packets to the controller.
  • If AP uplink VLAN is configured, that VLAN is used for creating GRE tunnel else Native VLAN is used.
  • If AP uplink VLAN is a trunk port (with no uplink VLAN is configured), multicast aggregation happens on the Native VLAN
  • If AP uplink is a trunk port with native vlan as x and allowed vlans as x,y,z and ‘uplink-vlan’ configured as vlan y for AP, then multicast aggregation happens on VLAN y 

 

GUI- Configuration

 

CLI- configuration 

(Aruba 7210) (config) #ap system-profile airgroup
(Aruba 7210) (AP system profile "airgroup") #ap-multicast-aggregation 
(Aruba 7210) (AP system profile "airgroup") #ap-multicast-aggregation-allowed-vlan 874

 

 

Debugging commands:

 

Command to show if AP is acting a multicast forwarder

One AP acts as multicast forwarder for each VLAN. The command shows if the AP is acting as a multicast forwarder.

 

 

 

 

Version history
Revision #:
2 of 2
Last update:
‎07-16-2015 03:45 AM
Updated by:
 
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