Internet exchange points and Internet routing

The Internet is a network of Autonomous Systems (ASes) comprising of a complex and complicated ecosystem of net- works used for a wide variety of applications. ASes exhibit varied functionality and communicate according to predefined rules to maintain distinct business objectives; termed intra- AS relations. These relations are one of two types: customer- provider (hierarchical) or peering (flat). Recent studies of intra-AS relations indicate the gradual transition of the In- ternet ecosystem from the hierarchical structure to a flatter peering architecture [1]. This infrastructure level flattening is characterized by the constant growth, rewiring and deaths of inter-AS links. Primary driving forces behind these changes are economic; especially the meteoric rise in popularity of organizations such as Facebook, Google, Yahoo and Microsoft, who have lately deployed large, private WAN infrastructures [1]. The transition from the hierarchical Internet has also accelerated with the deployment of multiple Internet eXchange Points (IXPs) worldwide, the facilitator of peering. Numerous peering links (between ASes) at these IXPs have recently been uncovered but their effects on Internet topology and inter- domain routing performance not yet examined. Exchange points (shown in fig 1) provide an infrastructure for ASes to set up mutually agreeable peering agreements at a common location and enable the quick exchange of traffic without requiring higher tier transit providers. They also facilitate dynamic changing of peering agreements be- tween Internet Service Providers (ISPs) providing transit to customer ASes. These customer ASes obtain better network performance (lesser delays, more reliability) while the ISPs save substantially on transit costs.