WAN optimization is a collection of techniques for increasing data-transfer efficiencies across wide-area networks.
Deduplication: The technique is used to improve storage utilization and can also be applied to network data transfers to reduce the number of bytes that must be sent across a link. In the deduplication process, unique chunks of data, or byte patterns, are identified and stored during a process of analysis. As the analysis continues, other chunks are compared to the stored copy and whenever a match occurs, the redundant chunk is replaced with a small reference that points to the stored chunk. Given that the same byte pattern may occur dozens, hundreds, or even thousands of times (the match frequency is dependent on the chunk size), the amount of data that must be stored or transferred can be greatly reduced.
Compression- zip style compression on the fly
Latency optimization – Can include TCP refinements such as window-size scaling, selective Acknowledgements, Layer 3 congestion control algorithms.