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Virtual Extensible LAN

From Wikipedia, the free encyclopedia

Virtual eXtensible LAN (VXLAN) is a network virtualization technology that uses a VLAN-like encapsulation technique to encapsulate OSI layer 2 Ethernet frames within layer 4 UDP datagrams, using 4789 as the default IANA-assigned destination UDP port number,[1] although many implementations that predate the IANA assignment use port 8472. VXLAN attempts to address the scalability problems associated with large cloud computing deployments.[2] VXLAN endpoints, which terminate VXLAN tunnels and may be either virtual or physical switch ports, are known as VXLAN tunnel endpoints (VTEPs).[3][4]

History

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VXLAN addresses the limitations of the VLAN standard for segmenting a physical network into multiple virtual networks. The 12-bit VLAN identifier limits the number of virtual networks on a physical network to 4096, while in some applications, IEEE 802.1ad can be used to extend this limit, this is generally insufficient for large-scale cloud computing infrastructures with many tenants. Also, the VXLAN standard provides for extending a virtual network across multiple geographically distributed physical networks by encapsulating layer 2 frames in UDP packets. This is useful for large distributed data centers.[5]

VXLAN is an evolution of efforts to standardize on an overlay encapsulation protocol that addresses these issues. Compared to single-tagged IEEE 802.1Q VLANs, which provide a limited number of layer-2 VLANs (4094, using a 12-bit VLAN ID), VXLAN increases scalability up to about 16 million logical networks (using a 24-bit VNID) and allows for layer-2 adjacency across IP networks. Multicast or unicast with head-end replication (HER) is used to flood Broadcast, unknown-unicast and multicast traffic.[6]

The VXLAN specification was originally created by VMware, Arista Networks and Cisco.[7][8]

Implementations

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VXLAN is widely, but not universally, implemented in commercial networking equipment. Several open-source implementations of VXLAN also exist,[9] including built-in capabilities in the Linux kernel.[10]

Commercial

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Arista, Cisco, and VMware were the originators of VXLAN and support it in various products.

Other backers of the VXLAN technology include Adtran,[11] Arrcus, Big Switch Networks, Broadcom, Citrix, Cumulus Networks, Dell EMC, Ericsson, Huawei,[12] Joyent, Juniper Networks, Mellanox,[13] MikroTik,[14] Netgate, Netgear, [15] Pica8, and Red Hat.[16]

Open source

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Standards specifications

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VXLAN is officially documented by the IETF in RFC 7348.[16] VXLAN encapsulates a MAC frame in a UDP datagram for transport across an IP network,[20] creating an overlay network or tunnel.

Alternative technologies

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Alternative technologies addressing the same or similar operational concerns include:

  • IEEE 802.1ad ("Q-in-Q"), which greatly increases the number of VLANs supported by standard IEEE 802 Ethernet beyond 4K.
  • IEEE 802.1ah ("MAC-in-MAC"), which supports tunneling Ethernet in a way that greatly increases the number of VLANs supported while avoiding a large increase in the size of the MAC Address table in a Carrier Ethernet deployment.
  • Network Virtualization using Generic Route Encapsulation (NVGRE), which uses different framing but has similar goals to VxLAN.

See also

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References

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  1. ↑ Herrod, Steve (August 30, 2011). "Towards Virtualized Networking for the Cloud". VMware. Archived from the original on 2011-09-12. Retrieved 2013-02-25.
  2. ↑ "Configuring VXLANs" (PDF). Cisco. Retrieved 2024-04-17.
  3. ↑ Andre Pech (2013-11-08). "Running OpenStack over a VXLAN Fabric" (PDF). openstack.org. pp. 8, 12. Retrieved 2016-07-04.
  4. ↑ "Open vSwitch Manual: vtep – hardware_vtep database schema". openvswitch.org. Retrieved 2016-07-04.
  5. ↑ "Understanding VXLAN (Virtual eXtensible Local Area Network)". ExamLabs. Retrieved 13 June 2026.
  6. ↑ "Arista Expands Leaf Switch Product Portfolio" (Press release). Arista Networks. 22 October 2014. Retrieved 8 November 2014. Arista's updated VXLAN implementation eliminates the need for multicast in the underlay network by using Head End Replication for forwarding broadcast, multicast and unknown unicast traffic
  7. ↑ Timothy Prickett Morgan (30 August 2011). "VMware, Cisco stretch virtual LANs across the heavens". The Register. Retrieved 2013-02-25.
  8. ↑ "VXLAN Bridges Virtual and Physical Networks to the Cloud" (PDF). Retrieved 2013-12-01.
  9. ↑ "VXLANs". Open vSwitch. Retrieved 2026-05-12.
  10. ↑ "Virtual eXtensible Local Area Networking documentation". Retrieved 2026-05-12.
  11. ↑ https://www.adtran-networks.com/-/media/adva-main-site/resources/data-sheets/pdfs/fsp-150-xg-480.ashx
  12. ↑ "Huawei CE12800 Series Data Center Switches - Huawei products". Huawei. December 2012.
  13. ↑ Timothy Pricket Morgan (April 23, 2013). "Mellanox adds VM-flitting to ConnectX-3 adapters - Going Pro with VXLAN". The Register.
  14. ↑ "VXLAN - RouterOS - MikroTik Documentation". help.mikrotik.com.
  15. ↑ ?https://www.netgear.com/assets/campaign/121401/images/m4500.pdf
  16. 1 2 M. Mahalingam; D. Dutt; K. Duda; P. Agarwal; L. Kreeger; T. Sridhar; M. Bursell; C. Wright (August 2014). Virtual eXtensible Local Area Network (VXLAN). Internet Engineering Task Force. doi:10.17487/RFC7348. ISSN 2070-1721. RFC 7348. Informational.
  17. ↑ "FreeBSD 10.2-RELEASE Release Notes". The FreeBSD Project. Retrieved 30 June 2016.
  18. ↑ Reyk Floeter (October 14, 2013). "OpenBSD vxlan implementation". Reyk Floeter. Archived from the original on October 29, 2014. Retrieved October 14, 2013.
  19. ↑ "Linux Virtual eXtensible Local Area Networking documentation". Linux Kernel documentation. Retrieved Sep 4, 2025.
  20. ↑ M. Mahalingam (February 22, 2013). "What Is VXLAN". Huawei. Retrieved 2013-02-25.
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