ransport networks. 7 Including IMS components for both EPS and WiMAX. Transmission Networks Public peered Backbones IP Transit Provider Internet Customer Edge IP Backbone Privately peered Backbones Figure 7.25 High level IP Transit/Peering architecture 7.5.2 Access to Internet (Interconnection) The access to Internet is provided by two transport methods, namely IP Transit and Peering. A high level IP Transit and Peering architecture is shown in Figure 7.25. There are three categories of Internet Service Providers (ISPs) and these are: An ISP that has access to the global Internet without purchasing transit form anyone. Includes AT&T, NTT Communications, Sprint, Verizon Biz, etc. An ISP relying on both peering and IP transit in order to reach the entire Internet. Includes France Telecom, Telecom Italia Sparkle, etc. An ISP having only IP transit agreements (no peering) to access Internet. 7.5.2.1 IP Transit IP Transit is a packaged solution produced by an international carrier who also manages and operates the service. The transit service is typically priced per megabit per second per month, and customers are often required to commit to a minimum volume of bandwidth, and usually to a minimum term of service as well [39]. The IP Transit services are usually provided to those customers who hold an Autonomous System (AS) number. An autonomous system is a collection of connected IP routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the Internet. The standard routing protocol is BGP (Border Gateway Protocol) while the standard line protocol is IPv4. BGP maintains tables of IP networks which designate network reach ability among autonomous systems. The Internet connectivity is usually provided in the range of 1.54 Mbps to 10 Gbps. The customer traffic is carried via SONET/SDH [OC-48/OC-192 (STM-16/STM-64)] and DWDM technologies. The intercontinental Internet traffic is handled by SEA-ME-WE (South-East Asia - Middle East - Western Europe 3) and va