Thorough dissection of SD-WAN service

  • A company with multiple locations that are physically separated connects each other with a WAN. The technology called “SD-WAN  ” that simplifies the construction and operation of such a WAN is attracting attention. This is because services that make it possible to use SD-WAN are appearing one after another. Using these services is expected to reduce the operational load on the WAN.

     The SD-WAN service provides a “portal site” that allows users to configure WAN settings and visualize the network status and usage status, enabling centralized management of the WAN. Portal sites are often prepared on the cloud by SD-WAN service providers.

     A dedicated device “CPE  ” for WAN connection is placed at each site connected by WAN CPE of SD-WAN is "which can be controlled from the portal site VPN  helpful to think of the router." These two factors allow users to use SD-WAN.

     SD-WAN was born as an application of SDN  , a technology for flexibly controlling networks with software, to the WAN ( Figure 1-1 ). The common point between SDN and SD-WAN is that the “control plane” that controls the network and the “data plane” that transfers data are clearly separated.


    In SDN, the controller implemented as an appliance  or software has the role of a control plane. From here, the LAN is dynamically controlled by controlling the switch in charge of the data plane. The protocol called OpenFlow is often used for communication between the controller and the switch.

     In SD-WAN, the portal site corresponds to the control plane and the CPE corresponds to the data plane. By separating them, the network route can be flexibly switched and new bases can be easily added. However, unlike SDN, there are few SD-WAN services that exchange OpenPort between the portal site and CPE.

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