SD WAN Part (1)

Before introducing about Software-Defined WAN technology, the challenges in traditional WAN networks will be explained first. It is critical to have a good bandwidth in the WAN links (to enable high performance or quick access) when the users in any branches or locations access an organization’s datacenter or different types of cloud services. In traditional WAN, to secure in data transmission between datacenter and branches, Multiprotocol Label Switching (MPLS) circuits or private circuits are used at higher costs. Moreover, there may have two or more WAN links for redundancy but these links can’t perform load balancing. This means that the other link(s) acts like backup while the primary link is performing. That is one of the drawbacks of traditional WANs. The other disadvantage is that there is no visibility whether the applications have enough bandwidth and latency passing over the WAN link. Besides, in traditional WANs, control plane, management plane and data plane are put all together under one device, i.e each device or router stores the information (such as their neighbor and the branches or site which is tunnel up form them) into a box. If there is a hundred sites, each device must store the information concerning with a hundred sites. Therefore, when our network uses fully mesh or partial mesh topology, it would be complex to control and manage from the sight of network infrastructure view. And also it is highly priced for skillful network administrators in every sites to manage the infrastructure. The other fact is if there is an issue in the control plane of a device, we need to reboot this router. As above, since control plane, data plane and management plane are all in one router, there are some impact in production traffic, data plane. These are the challenges occurred in normal traditional WAN networks.
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The best solution to overcome the above challenges is SD-WAN technology. Using SD-WAN in our organization makes applications which are sensitive to bandwidth and latency to choose the WAN link which is appropriate with their needs and allows load balancing. At the point of service level agreement, the latency and bandwidth over the WAN links are also fully visible. In SD WAN, since the three layers are separated, there is no matter whether the network infrastructure uses any topology. Each device or router can exchange information like their neighbors and tunnel up information between sites by the controller. Since the controller performs centralize management between sites, it won’t be complex and doesn’t need the skillful network administrator in every site, and also seems less cost from the sight of people from management level. In addition, even if an issue appears in control plane, the controller might be rebooted and there is no impact on data plane. These are the facts to overcome the challenges of using traditional WAN networks.
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Lastly, by using SD WAN, the customers can manage to simplify their WAN network. I would like to end the article saying SD WAN not only reduce cost for WAN operations but also can monitor the organization’s critical application over the WAN link from a single location.