If we doing clone/create of vxlan interface automatically will be doing adjust of vxlan MTU according multicast vxlandev interface. I believe that behavior should be like as vlan and bridge interfaces when attache member to them. They acquire mtu according its attached member.
Created attachment 211174 [details] Patch for that feature
Created attachment 257869 [details] Patch for that feature ^Triage: rebase patch.