Path optimization. In Section 3, we listed some of the limitations of BGP and the reasons why the routes it defines are often less than optimal. In many cases, better performance can be achieved by sending traffic via an alternate path—i.e. by directing it through an intermediate server on the Akamai network. Similar to approaches described in [17], [37], [36], and [38], Akamai leverages its distributed network as an Internet overlay. Internet topology and performance data from Akamai‘s mapping system described in Section 7.2) are used to dynamically select potential intermediate nodes fora particular path. Then, depending on the scenario, the Akamai network may conduct races to determine which path to use, or it may send communications over multiple paths for added resiliency. In [34], analysis of global data collected from the Akamai network reveals that many paths, particularly in Asia, can experience a 30-50% performance improvement when using the overlay Related research [6], [38] has noted similar results, albeit in noncommercial settings across networks of much smaller scale. Note that in addition to performance improvements, the overlay also increases reliability of communications by offering alternative paths in case connectivity should become severely degraded for the direct path. Figure 4 shows how Akamai maintained high connectivity for customers during the 2008 cable cuts that caused widespread Internet outages in the Middle East, Asia, and Africa.
