Virtual Extensible LAN

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]

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] Other backers of the VXLAN technology include Huawei,^[8] Broadcom, Citrix, Pica8, Big Switch Networks, Arrcus, Cumulus Networks, Dell EMC, Ericsson, Mellanox,^[9] FreeBSD,^[10] OpenBSD,^[11] Red Hat,^[12] Joyent, and Juniper Networks.

VXLAN is officially documented by the IETF in RFC 7348.^[12] VXLAN encapsulates a MAC frame in a UDP datagram for transport across an IP network,^[13] creating an overlay network or tunnel.

Open vSwitch is an example of a software-based virtual network switch that supports VXLAN overlay networks.

See also

• 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 QinQ.
• NVGRE, a similar competing specification
• Overlay Transport Virtualization (OTV)
• Virtual LAN (VLAN)
• Layer 2 Tunneling Protocol (L2TP)

References

1. Steve Herrod (August 30, 2011). "Towards Virtualized Networking for the Cloud". VMware. 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. "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
6. Timothy Prickett Morgan (30 August 2011). "VMware, Cisco stretch virtual LANs across the heavens". The Register. Retrieved 2013-02-25.
7. "VXLAN Bridges Virtual and Physical Networks to the Cloud" (PDF). Retrieved 2013-12-01.
8. "Huawei CE12800 Series Data Center Switches - Huawei products". Huawei. December 2012.
9. Timothy Pricket Morgan (April 23, 2013). "Mellanox adds VM-flitting to ConnectX-3 adapters - Going Pro with VXLAN". The Register.
10. "FreeBSD 10.2-RELEASE Release Notes". The FreeBSD Project. Retrieved 30 June 2016.
11. Reyk Floeter (October 14, 2013). "OpenBSD vxlan implementation". Reyk Floeter.
12. Mahalingam, Mallik; Dutt, Dinesh G.; et al. (August 2014). VXLAN: A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks. IETF. doi:10.17487/RFC7348. RFC 7348.
13. M. Mahalingam (February 22, 2013). "What Is VXLAN". Huawei. Retrieved 2013-02-25.

External links

• VXLAN Deep Dive: Part 1 and Part 2, November 2012, by Joe Onisick