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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
[edit]VXLAN is an evolution of efforts to standardize on an overlay encapsulation protocol. 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.[5]
The VXLAN specification was originally created by VMware, Arista Networks and Cisco.[6][7]
Implementations
[edit]VXLAN is widely, but not universally, implemented in commercial networking equipment. Several open-source implementations of VXLAN also exist.
Commercial
[edit]Arista, Cisco, and VMware were the originators of VXLAN and support it in various products.
Other backers of the VXLAN technology include Huawei,[8] Broadcom, Citrix, Pica8, Big Switch Networks, Arrcus, Cumulus Networks, Dell EMC, Ericsson, Mellanox,[9] Red Hat,[10] Joyent, and Juniper Networks.
Open source
[edit]- FreeBSD,[11]
- OpenBSD,[12]
- Open vSwitch is an example of a software-based virtual network switch that supports VXLAN overlay networks.
Standards specifications
[edit]VXLAN is officially documented by the IETF in RFC 7348.[10] VXLAN encapsulates a MAC frame in a UDP datagram for transport across an IP network,[13] creating an overlay network or tunnel.
Alternative technologies
[edit]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 which 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
[edit]- Distributed Overlay Virtual Ethernet (DOVE)
- Ethernet VPN (EVPN)
- GENEVE, an industry effort to unify both VXLAN and NVGRE technologies
- Generic routing encapsulation (GRE)
- IEEE 802.1ad, an Ethernet networking standard, also known as provider bridging, Stacked VLANs, or simply Q-in-Q.
- IEEE 802.1ah, an IEEE Ethernet networking standard, also known as Provider Backbone Bridging (PBB) or MAC-in-MAC.
- NVGRE, Network Virtualization using GRE, which is a similar competing specification to VxLAN.
- Overlay Transport Virtualization (OTV)
- Virtual LAN (VLAN)
- Layer 2 Tunneling Protocol (L2TP)
References
[edit]- ^ Herrod, Steve (August 30, 2011). "Towards Virtualized Networking for the Cloud". VMware. Archived from the original on 2025-08-05. Retrieved 2025-08-05.
- ^ "Configuring VXLANs" (PDF). Cisco. Retrieved 2025-08-05.
- ^ Andre Pech (2025-08-05). "Running OpenStack over a VXLAN Fabric" (PDF). openstack.org. pp. 8, 12. Retrieved 2025-08-05.
- ^ "Open vSwitch Manual: vtep – hardware_vtep database schema". openvswitch.org. Retrieved 2025-08-05.
- ^ "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
- ^ Timothy Prickett Morgan (30 August 2011). "VMware, Cisco stretch virtual LANs across the heavens". The Register. Retrieved 2025-08-05.
- ^ "VXLAN Bridges Virtual and Physical Networks to the Cloud" (PDF). Retrieved 2025-08-05.
- ^ "Huawei CE12800 Series Data Center Switches - Huawei products". Huawei. December 2012.
- ^ Timothy Pricket Morgan (April 23, 2013). "Mellanox adds VM-flitting to ConnectX-3 adapters - Going Pro with VXLAN". The Register.
- ^ a b 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.
- ^ "FreeBSD 10.2-RELEASE Release Notes". The FreeBSD Project. Retrieved 30 June 2016.
- ^ Reyk Floeter (October 14, 2013). "OpenBSD vxlan implementation". Reyk Floeter.
- ^ M. Mahalingam (February 22, 2013). "What Is VXLAN". Huawei. Retrieved 2025-08-05.
External links
[edit]- VXLAN Deep Dive: Part 1 and Part 2, November 2012, by Joe Onisick