One of the challenges facing WAN managers is the poor performance of applications that are developed using chatty protocols.
Chatty protocols, such as HTML, pass large amounts of overhead data back and forth between sender and receiver in a sequence of exchanges before any real user data is transmitted. In virtually all cases, merely increasing the size of the WAN pipes will not appreciably improve the performance of these applications.
Compounding this problem is the fact that most companies are taking file servers out of branch offices and centralizing them in corporate data centers. This means that chatty file access protocols - such as Common Internet File System and Network File System, which were designed to run over a LAN - now have to run over a WAN.
A number of companies are addressing this problem by developing wide-area file services (WAFS). The goal of WAFS is laudable - make file access over a WAN perform as it would over a LAN. How well this goal is achieved depends on whose technology you implement.
The typical WAFS approach places an appliance in branch offices instead of in the standard file server. After that, there is not much commonality in terms of what functionality is provided and how it is implemented.
If your company is centralizing its file servers it is worthwhile to look at implementing WAFS. However, you need to take a close look at competing products, and if possible, try them in your environment.