Software Defined Networking (SDNs) has been the hottest topic in networking over the past few years, and will likely continue to be over the next couple. It's certainly dominated the traffic on this site and others.
Despite the high interest levels from network managers and the media, SDN adoption remains somewhat light. While the concepts of automation, centralized control, and programmability make sense to most network managers, where to deploy an SDN first isn't really that obvious. From a utopian perspective, one would want to apply the principals of SDNs to the entire network all at once. Bringing in a dose of reality, though, most organizations simply can't be that aggressive with network changes without putting the business at risk. For many companies, the network is the business, and this radical a shift, if not deployed correctly, could seriously jeopardize the business.
So where should a company look to leverage an SDN? I would recommend starting where the pain is the highest. Much of the SDN messaging I've seen has targeted the data center, but the wide area network (WAN) is where many organizations struggle to run the network. The current hub-and-spoke model has been in place for what seems like an eternity. As an industry, we've talked about moving away from this design for years now, but this shift never happens. Hub and spoke was fine when best effort and client/server traffic was the norm, but times have changed and more traffic is cloud-based, making it necessary for the WAN to evolve.
Cloud and mobile computing has now made internet traffic mission-critical. The concept of "good enough" is no longer good enough, and the volume of traffic continues to grow exponentially. Additionally, WebRTC, video, Microsoft Lync and other collaborative tools have increased the amount of peer-to-peer traffic further, adding the changing dynamics of the WAN.
One possible solution to these WAN challenges is to increase the level of meshing of the network. The degree of meshing required is unique to each business and is based on the type of applications being run. While this may sound appealing, from personal experience I can tell you that it's very difficult to run a fully or even partially meshed network. Troubleshooting can be difficult and configuration changes can be a nightmare with the traditional box-by-box management model of running a network. Additionally, determining where to create links, how to manage them, and when to terminate them all add to the complexity.
SDNs can help organizations increase the level of meshing without having to add to the complexity. If done correctly, the creation of new paths should be automated based on application needs. For example, let's say an organization was running video conferencing. The video application should be able to talk to an SDN controller and then tell the controller to create a link between the two locations engaging in a video call. Once the video session ends, the controller can send commands to the network to terminate the link.
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