Virtual Extensible LAN

Virtual Extensible LAN ( VXLAN ) is a network - virtualization method that serves the problems in very large environments by the limited number of vLANs occur to solve. It is in VXLANs order to MAC -based Layer 2 environments that in Layer 4 - UDP encapsulated datagrams. With VXLAN, a total of 16,777,215 (24 bit) Layer 2 environments are possible, which in turn can contain 4096 vLANs each. This is more than sufficient even for very large hosting providers .

VXLAN was originally developed by Cisco Systems , VMware and Arista Networks and defined as the standard by the IETF in RFC 7348 . The IANA has VXLAN the UDP port assigned to 4789, but there are older implementations that use other ports. The RFC therefore stipulates that the destination port must be configurable.

Structure of the header data area (VXLAN header)

The VXLAN header is located in the OSI layer model between the original L2 header and an outer L4 UDP header. It comprises 8 bytes. Within the VXLAN flag, the R bits (Reserved) must be set to 0 and the I bit must be set to 1. The reserved fields must be set to 0 when sending and ignored when receiving.

0	4th	8th	12	16		20th	24	28	31 bit
VXLAN flags (R | R | R | R | I | R | R | R)		Reserved
VXLAN Network Identifier (VNI)								Reserved

Web links

• RFC7348 Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks