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Cisco Aironet 1520, 1130, 1240 Series Wireless Mesh Access Points, Design and Deployment Guide, Release 6.0
OL-20213-01
Connecting the Cisco 1520 Series Mesh Access Point to Your Network
Note
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).
Using the CLI to Enable Multicast on the Mesh Network
•
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
}
Note
Multicast for mesh networks cannot be enabled using the controller GUI.
IGMP Snooping
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:
configure network multicast igmp snooping
enable
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
In the case of 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.