Layer 2 Flooding is not working!

[OrkhanRustamli]

Hello,

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 1.3.3.3

[JL421-Retired]

Do you have multicast enabled in the underlay?

[OrkhanRustamli]

@JL421-Retired , No, I don`t. I didn`t see it in any documentation requirement. Do you have any guide for it? Which mode? What node should be RP and etc.

[JL421-Retired]

https://www.cisco.com/c/en/us/td/docs/solutions/CVD/Campus/cisco-sda-design-guide.html#L2_Flooding

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 multicast-routing

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