BITAG report on Interconnection and Traffic Exchange on the Internet

The Internet is a complex “network of networks” where individual networks are linked together to form a global network. In order for end users connected to one network to access data and services connected to another network, these networks must “interconnect” with each other, either by directly connecting with each other or by indirectly connecting through intermediate networks. Internet network interconnection, often referred to as “peering” or “transit,” is an increasingly important topic as the Internet ecosystem continues to evolve. The term “interconnection” refers to the various means by which network providers attach to and move traffic between one another, and is a collection of business practices and technical mechanisms that allow individually managed networks to connect together for this purpose. There is no central authority that manages Internet interconnection – the overall system arises because of the many bilateral and multilateral decisions that various actors make to interconnect. Interconnection in the United States has evolved significantly since the early days of the Internet. Peering connections, where two networks interconnect without the use of intermediate networks, are increasingly the primary interconnection paths between networks, supplanting the model of hierarchical interconnection via a small group of long-distance network providers. In most cases, two parties seeking to interconnect are able to come to terms. In some cases after an agreement is reached, however, traffic volumes or other factors may change, which in rare cases have led to “de-peering” events. More commonly, such changes lead to a renegotiation of the manner or type of interconnection agreement between the two parties. Although peering disputes over traffic imbalances, and other reasons, are not new, peering disputes in the U.S. have been increasingly publicized in recent years.

With this report, BITAG’s Technical Working Group (TWG) aims to provide a technical reference on the subject of Internet interconnection, and presents a detailed review on how networks connect, the development and changes in connection models, motivations for connection, how networks manage traffic between each other and some of the challenges that arise as networks evolve.