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A VXLAN gateway is a solution that allows a virtual extensible LAN (VXLAN) to communicate with another network, particularly a virtual LAN (VLAN). In order for the traffic from a VXLAN to use services on physical devices in a distant network, the traffic must pass through a VXLAN gateway.
A VXLAN gateway takes advantage of a process called tunneling, the transmission of private network data through a public network so that the routing nodes in the public network remain unaware of it. In effect, the VXLAN gateway facilitates the extension of a Layer 2 network over a Layer 3 network. Each overlay is known as a segment. Communications between virtual machines (VMs) can only take place within individual segments, not across segments. VXLAN might be deployed, for example, in data centers on virtualized hosts spread across multiple racks.
VXLAN is an encapsulation protocol intended to allow migration of VMs across long distances. As such, VXLAN may play an important role in software-defined networking (SDN), an approach to networking in which flow control is decoupled from hardware and given to a software application called a controller. A VLAN is a local area network (LAN) with a definition that maps workstations on some other basis than geographic location (such as by department, type of user, or primary application).