Inner ethernet frame is send out of VXLAN interface. The outer UDP header has destination port set to 4789 and source port 3440. The recommended port range in https://tools.ietf.org/html/rfc7348#section-5 is 49152-65535

pkt = (Ether(src="02:00:00:00:00:01", dst="02:00:00:00:00:02") /
IP(src='192.168.2.1', dst='192.168.1.1') /
UDP(sport=15, dport=15, chksum=0))
VXLAN tunnel: source 172.16.1.1, destination 172.16.1.2, vni 2