SD-WAN talk

  • Before understanding SD-WAN, let's review what is WAN? It can be understood literally, the Wide Area Network, which is commonly referred to as the WAN. This is a telecommunications network or computer network that covers a long distance, usually built by renting telecommunications lines. The longer distances here can be across regions, across countries, and even the world. From the perspective of computer network protocols and concepts, WAN is concerned with computer network technology for long-distance data transmission. This technology is applied between LAN (Local Area Network), MAN (Metropolitan Area Network) and other local computer networks, enabling these local networks to connect into a connected wide area network. The figure below is a WAN diagram consisting of multiple MANs.

    The Internet that we are all related to in our daily lives is a WAN, a WAN that is covered all over the world. The Internet is built by an ISP (Internet Service Provider) to provide Internet services to various LANs. But it can't be said that WAN is the Internet. In the application of enterprises and organizations, there are more private WANs.

    The physical connection technologies of the WAN include telephone lines, radio waves, and optical fibers. In terms of the logical layer, the common WAN protocol is the early X.25, Frame Relay, and the current mainstream is MPLS, Leased Line (T1, T3) and so on. In particular, MPLS has taken a dominant position in WAN construction. 

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