NAME

VXLAN, vxlan — Virtual eXtensible Local Area Network

SYNOPSIS

#include <sys/vxlan.h>

DESCRIPTION

VXLAN (RFC 7348) is a network encapsulation protocol that is used by overlay(7) devices. A payload, commonly an Ethernet frame, is placed inside of a UDP packet and prepended with an 8-byte VXLAN header.

The VXLAN header contains two 32-bit words. The first word is an 8-bit flags field followed by 24 reserved bits. The second word is a 24-bit virtual network identifier followed by 8 reserved bits. The virtual network identifier identifies a unique VXLAN and is similar in concept to an IEEE 802.1Q VLAN identifier.

The system provides access to VXLAN through dladm overlays. See dladm(8) and overlay(7) for more information.

The <sys/vxlan.h> header provides information for working with the VXLAN protocol. The contents of this header are uncommitted. The header defines a structure that may be used to encode and decode a VXLAN header. It defines a packed structure type vxlan_hdr_t which represents the VXLAN frame header and has the following members:

	uint32_t	vxlan_flags;	/* flags in upper 8 bits */
	uint32_t	vxlan_id;	/* VXLAN ID in upper 24 bits */

EXAMPLES

Example 1 Decoding a VXLAN header

The following example shows how to validate a header. For more information on this process, see RFC 7348.

#include <sys/types.h>
#include <netinet/in.h>
#include <inttypes.h>
#include <sys/vxlan.h>

...

/*
 * Validate the following bytes as a VXLAN header. If valid, return
 * 0 and store the VXLAN identifier in *vidp. Otherwise, return an
 * error.
 */
int
validate_vxlan(void *buf, int len, uint32_t *vidp)
{
	vxlan_hdr_t *hdr;

	if (len < sizeof (vxlan_hdr_t))
		return (EINAVL);

	hdr = buf;
	if ((ntohl(hdr->vxlan_flags) & VXLAN_MAGIC) == 0)
		return (EINAVL);

	*vidp = ntohl(vxlan->vxlan_id) >> VXLAN_ID_SHIFT;

	return (0);
}

STABILITY

The contents of <sys/vxlan.h> are Uncommitted.

SEE ALSO

overlay(7), dladm(8)

Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger L., Sridhar, T., Bursell, M., and C. Wright, RFC 7348, Virtual eXtensible Local Area Network (VXLAN): A Framework, for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks, August 2014.