What Is an Overlay Network?

Overlay networks are virtual logical networks constructed on an underlay network using network virtualization technologies. Although different overlay networks share devices and lines on an underlay network, services on overlay networks are decoupled from physical networking and interconnection technologies on the underlay network. With the help of the multi-instance technology — core networking technology adopted by the SD-WAN and data center solutions, overlay networks can serve not only different services (such as multiple departments) of the same tenant but also different tenants.

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