When all APs are receiving multicast traffic instead of only the APs that need it, the issue is likely due to Multicast IGMP snooping not being enabled. Here’s why:
IGMP Snooping:
IGMP (Internet Group Management Protocol) snooping is a feature that allows switches to listen to IGMP messages and forward multicast traffic only to the ports where it is needed. If IGMP snooping is not enabled, the switch will flood multicast traffic to all ports, including those connected to APs that do not need the traffic.
Why it’s the cause:
Without IGMP snooping, the switch cannot determine which APs have clients interested in the multicast traffic. As a result, it sends the multicast traffic to all APs, causing unnecessary network congestion.
A. The multicast group includes all APs:
This is not a valid scenario because multicast groups are defined by IP addresses, not by APs. APs do not join multicast groups; clients do.
B. The wrong multicast address was used:
Using the wrong multicast address would result in the wrong clients receiving the traffic, but it would not cause all APs to receive the traffic.
C. The multicast group is assigned the wrong VLAN:
Assigning the multicast group to the wrong VLAN would prevent clients in the correct VLAN from receiving the traffic, but it would not cause all APs to receive the traffic.
Brothers, Answer is A, take a look below
"the controller snoops to learn which wirelessclients want to join which multicast groups on which APs. The multicast traffic will be forwardedto all APs over their CAPWAP tunnels via the CAPWAP multicast address. However, only theAPs hosting clients that are registered for the multicast group will transmit that traffic onto theWLAN. The other APs will not."
When IGMP Snooping is enabled on the WLC, still all the APs will receive the multicast traffic:
The multicast traffic will be forwarded to all APs over their CAPWAP tunnels via the CAPWAP multicast address. However, only the APs hosting clients that are registered for the multicast group will transmit traffic onto the WLAN.
Looks correct, when IGMP snooping is enabled, multicast traffic is sent only to the ports which sent IGMP joins. If IGMP snooping is disabled, then traffic is flooded to all the ports in that VLAN.
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