Cisco Cisco Aironet 1522 Lightweight Outdoor Mesh Access Point Guía De Diseño

If 802.11b clients need to receive CAPWAP multicasts, then multicast must be enabled 
globally on the controller as well as on the mesh network (using the config network 
multicast global enable CLI command). If multicast does not need to extend to 802.11b 
clients beyond the mesh network, the global multicast parameter should be disabled (using 
the config network multicast global disable CLI command).

To enable multicast mode on the mesh network to receive multicasts from beyond the mesh 
networks, enter these commands:

config network multicast global enable

config mesh multicast {regular | in | in-out}

To enable multicast mode only the mesh network (multicasts do not need to extend to 802.11b 
clients beyond the mesh network), enter these commands:

config network multicast global disable

config mesh multicast {regular | in | in-out}

Multicast for mesh networks cannot be enabled using the controller GUI.

IGMP snooping delivers improved RF usage through selective multicast forwarding, and optimizes 
packet forwarding in voice and video applications.

A mesh access point transmits multicast packets only if a client is associated with the mesh access point 
that is subscribed to the multicast group. So, when IGMP snooping is enabled, only that multicast traffic 
relevant to given hosts is forwarded. 

To enable IGMP snooping on the controller, enter:

A client sends an IGMP join which travels through the mesh access point to the controller. The controller 
intercepts the join and creates a table entry for the client in the multicast group. The controller then 
proxies the IGMP join through the upstream switch or router.

You can query the status of the IGMP groups on a router by entering the following command:

router# show ip gmp groups

IGMP Connected Group Membership

Group 

Address Interface 

Uptime 

Expires Last 

Reporter

233.0.0.1 Vlan119 

3w1d 

00:01:52 

10.1.1.130

For Layer 3 roaming, an IGMP query is sent to the client’s WLAN. The controller modifies the client’s 
response before forwarding, and changes the source IP address to the controller’s dynamic interface IP 
address.

The network hears the controller’s request for the multicast group and forwards the multicast to the new 
controller.