WAN Optimisation 101
WANs link together Local Area Networks (LANs) that may be located in different towns or even countries.
Managing Wide Area Network infrastructure is considerably more complex than managing a simple office LAN as there is much more traffic, a greater variety of technologies and equipment, and more users.
Unless the Wide Area Network is built entirely from leased lines, some or all of the underlying infrastructure will also be shared with other communications services and other customers.
So, it can be quite a challenge to create a WAN that offers predictable levels of performance at all times.
Irrespective of whether it is the service provider that is managing the WAN or the business does the task itself, WAN optimisation technologies can help improve the performance of the WAN.
WAN optimisation is particularly important for broadband services such as videoconferencing, which is very sensitive to Network congestion, or for mission-critical applications such as e-commerce, where poor performance can lead to lost customers and revenues.
These applications should have highest priority on the Network but, in the absence of WAN optimisation, they are in direct competition for bandwidth with other Network traffic, such as that generated by Network users surfing the web.
Each time a Network user requests a web page, the Network has to allocate a certain amount of bandwidth to send the request over the web and then later allocate bandwidth to fetch the content of the web page back from the web.
While the average data traffic on a WAN created by users surfing the web is usually predictable and fairly constant during the working day, there can be sudden peaks in web traffic, when an important news event occurs, for example. If the WAN is not optimised, these peaks in web traffic can clog the Network and negatively impact other traffic.
The congestion problem is more acute today with the growth of multimedia content and the popularity of social Networks.
For example, if a YouTube video suddenly goes viral, the WAN can quickly become saturated by hundreds of requests from users all wanting to stream the video.
WAN optimisation technologies overcome this problem by enabling businesses or service providers to set aside a minimum amount of bandwidth for mission-critical applications.
This is done by giving different priorities to different types of Network traffic. For example, surfing the web is not a business-critical application and so it can be given a lower priority to other types of Network traffic.
If the traffic levels on the Network get close to the maximum available bandwidth, one network optimisation strategy is to queue the low-priority traffic so that the high-priority traffic can still get through.
The effect on users will be that they experience a greater delay in viewing web pages than at times when the Network is not congested, but the delay is unlikely to negatively affect their work.
Much more sophisticated Network optimisations policies can be adopted to, for example, change the priorities for applications depending on the time of day, or to always prioritise traffic coming from certain Network hosts.
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