What is a WAN?
A WAN is a network that uses various links – private lines, Multiprotocol Label Switching , virtual private networks (, wireless ( the Internet – to connect smaller metropolitan and campus networks in diverse locations into a single, distributed network. The sites they connect could be a few miles apart or halfway around the globe. In an enterprise, the purposes of a WAN could include connecting branch offices or even individual remote workers with headquarters or the data center, in order to share corporate resources and communications.
WAN architecture
Initially, WANs were built with meshed webs of private lines bought from telecommunications carriers, but WAN architectures have advanced to include packet-switched services such as MPLS. With these services, a single connection to a site can be connected to many others via switching within service-provider networks. For certain types of traffic, the Internet can also be woven into the mix to provide less expensive WAN connections.
As companies look for WAN improvements, the use of software-defined technology is gaining momentum. Software-defined WAN (SD-WAN) takes software-defined concepts, especially the decoupling of the control plane from the data plane, and bring it to the wan.
SD-WAN uses software to monitor the performance of a mix of WAN connections – MPLS, dedicated circuits, the Internet – and to choose the most appropriate connection for each traffic type. So teleconferencing might run over a dedicated circuit, but email might use the Internet. In making its decisions, SD-WAN software takes into account how well each link is performing at the moment, the cost of each connection and the needs of each application.
WAN management and optimization
Because data transmission is still reliant on the rules of physics, the greater the distance between two devices, the longer it will take for data to travel between them. The greater the distance, the greater the delay. Network congestion and dropped packets can also introduce performance problems.
Some of this can be addressed using WAN optimization, which makes data transmissions more efficient. This is important because WAN links can be expensive, so technologies have sprung up that reduce the amount of traffic crossing WAN links and ensure that it arrives efficiently. These optimization methods include abbreviating redundant data (known as deduplication), compression, and caching (putting frequently used data closer to the end user).
History of WANs
WANs have been around since the early days of computing networks. The first examples of WANs included circuit-switched telephone lines, but advances in technologies now include wireless transmissions and fiber-optic transmissions. Data can also be moved via leased lines, or even via satellite transmission.
As technologies changed, so did transmission rates. The early days of 2400 bps modems evolved to 40 Gbps and 100 Gbps connectivity today. These speed increases have allowed more devices to connect to networks, witnessed by the explosion of computers, phones, tablets and smaller Internet of Things devices.
