Virtual eXtensible LAN (VXLAN) is a network virtualization technology that uses a

VLAN A virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer ( OSI layer 2).IEEE 802.1Q-2011, ''1.4 VLAN aims and benefits'' In this context, virtual refers to a ...

-like encapsulation technique to encapsulate OSI layer 2

Ethernet frame In computer networking, an Ethernet frame is a data link layer protocol data unit and uses the underlying Ethernet physical layer transport mechanisms. In other words, a data unit on an Ethernet link transports an Ethernet frame as its paylo ...

s within layer 4 UDP datagrams, using 4789 as the default

IANA The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Internet P ...

-assigned destination UDP port number, although many implementations that predate the IANA assignment use port 8472. VXLAN attempts to address the

scalability Scalability is the property of a system to handle a growing amount of work. One definition for software systems specifies that this may be done by adding resources to the system. In an economic context, a scalable business model implies that ...

problems associated with large

cloud computing Cloud computing is "a paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand," according to International Organization for ...

deployments. VXLAN endpoints, which terminate VXLAN tunnels and may be either virtual or physical switch ports, are known as VXLAN tunnel endpoints (VTEPs).

History

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 In computer networking, multicast is a type of group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast differs from ph ...

or unicast with head-end replication (HER) is used to flood Broadcast, unknown-unicast and multicast traffic. The VXLAN specification was originally created by VMware,

Arista Networks Arista Networks, Inc. (formerly Arastra) is an American computer networking company headquartered in Santa Clara, California. The company designs and sells Multilayer switch, multilayer network switches to deliver software-defined networking (SDN) ...

and

Cisco Cisco Systems, Inc. (using the trademark Cisco) is an American multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, s ...

Implementations

VXLAN is widely, but not universally, implemented in commercial networking equipment. Several open-source implementations of VXLAN also exist.

Commercial

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

Huawei Huawei Technologies Co., Ltd. ("Huawei" sometimes stylized as "HUAWEI"; ; zh, c=华为, p= ) is a Chinese multinational corporationtechnology company in Longgang, Shenzhen, Longgang, Shenzhen, Guangdong. Its main product lines include teleco ...

Broadcom Broadcom Inc. is an American multinational corporation, multinational designer, developer, manufacturer, and global supplier of a wide range of semiconductor and infrastructure software products. Broadcom's product offerings serve the data cen ...

, Citrix, Pica8, Big Switch Networks, Arrcus, Cumulus Networks, Dell EMC,

Ericsson (), commonly known as Ericsson (), is a Swedish multinational networking and telecommunications company headquartered in Stockholm, Sweden. Ericsson has been a major contributor to the development of the telecommunications industry and is one ...

, Mellanox,

Red Hat Red Hat, Inc. (formerly Red Hat Software, Inc.) is an American software company that provides open source software products to enterprises and is a subsidiary of IBM. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North ...

Joyent Joyent Inc. is a software and services company based in San Francisco, California. Specializing in cloud computing, it markets infrastructure-as-a-service. On June 15, 2016, the company was acquired by Samsung Electronics. Services Triton, Joyen ...

, and

Juniper Networks Juniper Networks, Inc. is an American multinational corporation headquartered in Sunnyvale, California. The company develops and markets networking products, including Router (computing), routers, Network switch, switches, network management so ...

Open source

FreeBSD FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable ...

, *

OpenBSD OpenBSD is a security-focused operating system, security-focused, free software, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by fork (software development), forking NetBSD ...

, * Open vSwitch is an example of a software-based virtual

network switch A network switch (also called switching hub, bridging hub, Ethernet switch, and, by the IEEE, MAC bridge) is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destinat ...

that supports VXLAN overlay networks.

Standards specifications

VXLAN is officially documented by the IETF in RFC 7348. VXLAN encapsulates a MAC frame in a UDP datagram for transport across an IP network, creating an

overlay network An overlay network is a logical computer network that is protocol layering, layered on top of a physical network. The concept of overlay networking is distinct from the traditional model of OSI model, OSI layered networks, and almost always assum ...

tunnel A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is usually completely enclosed except for the two portals common at each end, though there may be access and ve ...

Alternative technologies

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.

References

External links

VXLAN Deep Dive: Part 1
an
Part 2
November 2012, by Joe Onisick {{Virtualization software, state=collapsed Tunneling protocols