VxLAN: Use Layer 3 transport to carry layer 2 data. Any servers connected on different broadcast domain can talk to each other as if they are on same link.VXLAN is a MAC-in-IP/UDP encapsulation type, adding a total of 50 bytes to the original packet post-encapsulation. This is not just a single header, but multiple headers added to the original packet—this includes a VXLAN header, a UDP header, an IP header, and an Ethernet header.
VxLAN frame: outer Mac + outer IP + UDP + VxLAN + original frame ( DMAC + SMAC + Ether Type + Payload + CRC). outer MAC(14 bytes) + outer IP(10 bytes) + outer UDP(8 bytes) + VxLAN (8 bytes) = 50 bytes of extra bytes.
UDP destination port is 4789.
VxLAN header: Flags + RES + VNI(24 bits) + RES
VTEP: Switches and routers which participate in VxLAN has a special interface called VTEP. The VTEP provides connection between overlay and underlay. Each VTEP has IP address in the underlay network and VTEP also has one or more VNIs.
VXLAN Flood and Learn (F&L)
One alternative to IP multicast for handling multidestination traffic in a VXLAN environment is to use ingress replication (IR), or head-end replication.
With IR, every VTEP must be aware of other VTEPs that have membership in a given VNI. The source VTEP generates ncopies for every multidestination frame, with each destined to other VTEPs that have membership in the corresponding VNI.