I needed to enable Layer 2 flooding on one little subnet/vlan and I have enabled it on Virtual Network of Host Onboarding section same as https://community.cisco.com/t5/networking-documents/cisco-sd-access-layer2-flooding/ta-p/3943916. However, when I tested ping to broadcast from one switch to another, it was not working. What else can be possible cause which prevent flooding? I have multicast enabled on the same network. DNAC version is 220.127.116.11
Generally you would configure your RPs on your LAN Automation seed devices, or on the Core/Distribution layer of your design. I'll see if I can find the deeper guide to setting up multicast for the underlay.
I can't find anything more in-depth than this excerpt: Manually configure multicast on all underlay devices. This includes ip multicast-routing globally and ip pim sparse-mode on all routed uplinks.
Looking through my configs, it really is a fairly sparse config:
Loopback0 - ip pim sparse-mode, ip router isis
Transports - ip pim sparse-mode
ip pim rp-address $ipofanycastrp
ip pim register-source Loopback0
ip pim ssm default
Then on your RPs you add:
ip msdp peer $ipofpeer connect-source loopback0
Loopback60000 - Anycast ip address, ip router isis