To understand the different techniques used by appliances offering WAN optimization, it's important to first define exactly what exactly a 'WAN' is. WAN stands for 'wide area network' and refers to any network that covers a very large geographic area. By contrast, a LAN, or local area network, refers to networks that provide internal communication in a home or small office. The internet as a whole can be defined as a WAN and is obviously a public network, while an example of a private WAN could be a corporation with offices in San Francisco, San Jose, Austin, Boston, and New York. Each individual office would have a LAN set up internally, but could also use DSL or MPLS connections to form a WAN to share information between offices.
There are a number of performance-related issues that typically occur with WANs, which has led to the development of various WAN optimization techniques. These issues can include redundant transmissions, 'chatty' protocols, and packet delivery issues. Some of the common techniques used to achieve WAN optimization include: Bandwidth Management; Caching; and Protocol Optimization. Multiple vendors offer WAN optimization appliances that use a number of these techniques to process the IP traffic traveling between the sites over the company's WAN. Not every solution uses the same techniques, thus the benefits can vary, which is important to understand when researching a vendor or supplier.
Bandwidth Management allows applications to have set limits and minimums with regard to how much bandwidth they use. For example, this technique would allow you to put a limit on the amount of bandwidth an especially avaricious application can use. Conversely, bandwidth management can ensure that less-used applications always have a guaranteed amount of bandwidth allocated to them.
Caching allows several copies of important files, especially larger ones, to be stored in multiple locations. This prevents users from having to download files as large as 20MB or 100MB across a WAN connection every time they need to view or make edits to it. Additionally, whenever modifications are made to one of these cached files, the network doesn't have to transmit the entire updated file to every one of its multiple locations. One the portions of the file that have been edited are sent.
Communication protocols for digital computer network communication have features intended to ensure reliable interchange of data over an imperfect communication channel. It is basically a way of following certain rules so that a system works properly. Protocol optimization restricts the amount of electronic chit-chat that occurs between sites when communication protocols send their necessary back and forth confirmation messages.
The implementation of these various techniques by using WAN optimization appliances has been said to reduce the usage of bandwidth by as much as 50-95% between offices communicating over the WAN. For many companies this means thousands of dollars of savings, particularly when costly solutions like multiple MPLS networks are being to ensure network reliability. For others, the value of WAN optimization is that global collaboration allows the company to undertake tasks that it previously couldn't. Regardless of the benefit or the need, understanding the latest in WAN Optimization techniques can have a substantial benefit on the performance of a modern corporation.
Charles Hughes is author of this article on WAN Optimization.
