VXLAN and multicast

[Leftz]

Hi, As we know vxlan needs multicast config. If using broadcast instead of multicast, what would happen? thanks

[MHM Cisco World · Accepted solution]

You can not use Broadcast !!! Yes you can not why ? because we run VXLAN over L3 underlay and L3 underlay can not accept broadcast (L3 behave) but it accept multicast. 
so we broadcast over L3 multicast. 

[Leftz]

Thanks for your reply. 

"L3 underlay can not accept broadcast (L3 behave) but it accept multicast.  .." 

Its because L3 underlayer would get mess with broadcast, or something else? 

[MHM Cisco World]

router by default will not forward broadcast traffic. 
as you know the router not like SW forward broadcast. 

[MHM Cisco World]

[Leftz]

Right, so each VTEP communicate each other via multicast. and can we say VXLAN is used only on ACI? if so, there should be some table in leaf and spine to allow us to check their status, right? 

[MHM Cisco World]

Yes each other connect via multicast.

[Leftz]

Thank you!