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Global Internet Exchange (GIX) is a global network of peer-based Internet exchange points (IXP or IX) used for the exchange of traffic between Internet Service Providers (ISP) and large networks. IXPs provide the physical infrastructure (routers, switches and other support equipment), which serve as the a foundation for traffic exchange between ISPs. This provides a low cost, redundant, fail-safe, route-based and low latency alternative to more expensive and transit-based links to high-tier ISPs.
The Internet is a complex hierarchal network that serves as a global base for ISP and client data exchange. ISP traffic is routed within other ISPs, according to client requests. Clients connect to Tier3 ISPs, which use a direct link to connect to Tier 2 ISPs, which provide interconnectivity between Tier 3 ISPs, as well as traffic routing to the Tier-1 network (the Internet).
Tier 2 ISPs charge Tier 3 ISPs for bandwidth and traffic volume, which is costly and inefficient and induces unnecessary latency - even if the source and destination are geographically close. As an alternative to transit-based links, ISPs also use IXPs for interconnectivity. These Internet exchange points (IEP) provide a physical location in which ISPs can exchange traffic without bandwidth and volume limitations. Both networks are often located in the same city, so direct interconnection reduces latency.
Commercial and community-based IXPs exist in GIX networks. IXP peering agreements are normally signed to bear setup costs. Expensive exchanges require that participants pay annually or monthly, depending on port speed. Fiber Distributed Data Interface (FDDI), Asynchronous Transfer Mode (ATM), Fast Ethernet and Gigabit Ethernet are the most widely used technologies in GIX and IXP setups. Border Gateway Protocol (BGP) forms the routing backbone and Multiprotocol Label Switching (MPLS) forms the switching backbone. Most IXPs within GIX networks leave session configuration to individual members that contact and configure individual sessions between each other. Many IXPs in GIX networks also implement Multi-lateral Peering (MLP), where each member peers with a route-server, which automatically distributes routes to other members that peer with the route-server.