TORIX NYIIX LAIIX TOP-IX Netnod Mix Milano ix.br SP Peering and BGP A great deal of the complexity in the BGP routing protocol exists to aid the enforcement and fine-tuning of peering and transit agreements. BGP allows operators to define a policy that determines where traffic is routed. Three things commonly used to determine routing are local-preference, multi exit discriminators (MEDs) and AS-Path. Local-preference is used internally within a network to differentiate classes of networks. For example, a particular network will have a higher preference set on internal and customer advertisements. Settlement free peering is then configured to be preferred over paid IP transit. Networks that speak BGP to each other can engage in multi exit discriminator exchange with each other, although most do not. When networks interconnect in several locations, MEDs can be used to reference that network's interior gateway protocol cost. This results in both networks sharing the burden of transporting each other's traffic on their own network (or cold potato). Hot-potato or nearest-exit routing, which is typically the normal behavior on the Internet, is where traffic destined to another network is delivered to the closest interconnection point. Law and policy Internet interconnection is not regulated in the same way that public telephone network interconnection is regulated. Nevertheless, Internet interconnection has been the subject of several areas of federal policy in the United States. Perhaps the most dramatic example of this is the attempted MCI Worldcom/Sprint merger. In this case, the Department of Justice blocked the merger specifically because of the impact of the merger on the Internet backbone market (thereby requiring MCI to divest itself of its successful "internetMCI" business to gain approval). In 2001, the Federal Communications Commission's advisory committee, the Network Reliability and Interoperability Council recommended that Internet backbones publish their peering policies, something that they had been hesitant to do beforehand. The FCC has also reviewed competition in the backbone market in its Section 706 proceedings which review whether advanced telecommunications are being provided to all Americans in a reasonable and timely manner. Finally, Internet interconnection has become an issue in the international arena under something known as the International Charging Arrangements for Internet Services (ICAIS). In the ICAIS debate, countries underserved by Internet backbones have complained that it is unfair that they must pay the full cost of connecting to an Internet exchange point in a different country, frequently the United States. These