Configuring Multicast Packet Forwarding to User VLAN on Catalyst 9800

[LSW7716]

I'm encountering challenges in configuring the forwarding of Multicast packets to the user VLAN on a Catalyst 9800, version 17.9.4. Here are the conditions and issues I'm experiencing:

• Desired: To disable IGMP Snooping.
• Objective: To forward Multicast packets from the C9800 through APs to wireless client devices without configuring multicast routing on switches or routers.

Following the Configuration Guide for Wireless Multicast setup, when sending Multicast packets from VLAN 50 on the wired side, the C9800 seems to receive these packets and forwards them using the management VLAN 100 instead of the intended VLAN 50. Consequently, neither the APs nor the wireless client devices receive these packets.

The ideal packet flow should involve the C9800 receiving packets on VLAN 50, encapsulating them with CAPWAP, and flooding them to wireless client devices through APs associated with the WLAN configured for VLAN 50.

Is there a recommended setup or configuration adjustments that would allow the Catalyst 9800 to correctly forward these Multicast packets as desired?

I'd appreciate any guidance or assistance on configuring the C9800 to achieve this Multicast packet forwarding to the user VLAN.

Thank you for your help.

[Rasika Nayanajith]

You have to enable multicast on your wired network for the vlan on WLC management and AP management. Otherwise your AP won't receive multicast traffic send by WLC (encapsulated in capwap)

HTH
Rasika
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[LSW7716]

Thank you for the response.

In the wired network, we've disabled Multicast routing and IGMP Snooping, and it's challenging to modify this design. We've previously used the WLC5500 series and were able to forward Multicast packets in Multicast Unicast mode. We aim to continue forwarding Multicast packets without altering the wired network's configuration in the future.

[Rasika Nayanajith]

WLC point of view, if it has to send all wireless multicast to each individual APs as unicast, that is not the ideal design. Pls refer 9800 best practice document given below
https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9800-series-wireless-controllers/guide-c07-743627.html#Multicast 

"Multicast-forwarding mode is the recommended setting. Use unicast forwarding only for small deployments and when multicast routing support in the network infrastructure is not possible. Unicast forwarding is not supported on the C9800-80, C9800-40, and C9800-CL medium and large template platforms."

HTH
Rasika
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[MHM Cisco World]

@Rasika Nayanajith fully correct

9800 not send multicast it instead replicated unicast to all ap/clients.

MHM

[Rasika Nayanajith]

At the AP (over the air) it convert Multicast to Unicast to provide QoS, Reliability and faster transmission. By default Wireless Multicast traffic goes highest basic rates (6-54Mbps) configured.
WLC (9800) to APs, it is recommend to use Multicast delivery to have efficient traffic flow on your wired network. That is what above best practices document explain. If it is a 9800 hardware platform or 9800-CL (VM) for excepts small scale deployment, Unicast methods is not supported

HTH
Rasika
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