WAN optimization is a collection of techniques for increasing
data-transfer efficiencies across wide-area networks. In 2008,
the WAN optimization market was estimated to be $1 billion, and
it will grow to $4.4 billion by 2014 according to Gartner, a
technology research firm. The most common measures of TCP data-
transfer efficiencies (i.e., optimization) are throughput,
bandwidth requirements, latency, protocol optimization, and
congestion, as manifested in dropped packets. In addition, the
WAN itself can be classified with regards to the distance
between endpoints and the amounts of data transferred. Two
common business WAN topologies are Branch to Headquarters and
Data Center to Data Center (DC2DC). In general, "Branch" WAN
links are closer, use less bandwidth, support more simultaneous
connections, support smaller connections and more short-lived
connections, and handle a greater variety of protocols. They are
used for business applications such as email, content management
systems, database application, an