Point d'échange Internet (IXP)

What Happens at an IXP

An Internet Exchange Point (IXP) is a shared physical infrastructure — typically one or more high-speed Ethernet switches — where multiple networks connect and exchange traffic directly. Participants called members connect their RouterA network device that forwards data packets between different networks by examining destination IP addresses and consulting its routing table. Routers operate at Layer 3 (Network) of the OSI model. to the IXP switch fabric and establish bilateral BGPBorder Gateway Protocol. The routing protocol that exchanges reachability information between autonomous systems, effectively determining how data traverses the internet. Often called the "postal service of the internet." PeeringA mutual arrangement between two networks to exchange traffic directly and freely (settlement-free peering) at an interconnection point, bypassing third-party transit providers. Peering reduces costs and latency for both parties. sessions with other members. Traffic flowing between two members crosses only the IXP switch, not any intermediate TransitA paid arrangement where one network (the customer) pays another (the transit provider) for access to the rest of the internet. Unlike peering, transit provides full routing table access and is the primary way smaller networks connect to the global internet. network. This reduces LatencyThe time delay for a data packet to travel from source to destination, typically measured in milliseconds (ms). Lower latency is critical for real-time applications like video calls, gaming, and financial trading. by shortening the network path and reduces cost by eliminating per-byte transit fees for that traffic.

Route Servers and Multilateral Peering

Most IXPs operate route servers: shared BGP speakers that redistribute routes among all consenting members without requiring bilateral sessions between every pair. A new IXP member can peer with hundreds of networks by establishing a single BGP session to the route server. Route servers apply filtering policies based on RPKI and IRR (Internet Routing Registry) data to prevent invalid BGPBorder Gateway Protocol. The routing protocol that exchanges reachability information between autonomous systems, effectively determining how data traverses the internet. Often called the "postal service of the internet." announcements from propagating — a defence layer against BGP HijackAn attack or misconfiguration where a network falsely announces ownership of IP prefixes it does not control, causing internet traffic to be rerouted through the attacker's network. Can be used for surveillance, traffic interception, or denial of service..

Scale and Distribution

Major IXPs such as DE-CIX Frankfurt, AMS-IX, and LINX handle hundreds of terabits per second of peak traffic from thousands of member networks. Many IXPs operate distributed across multiple data centers in the same metropolitan area, reducing distance constraints for membership. Content providers connect to dozens of IXPs globally to bring their CDNContent Delivery Network. A geographically distributed network of servers that caches and serves content from locations close to end users, reducing latency and improving load times. Major providers include Cloudflare, AWS CloudFront, and Akamai. nodes as close as possible to end users, minimising LatencyThe time delay for a data packet to travel from source to destination, typically measured in milliseconds (ms). Lower latency is critical for real-time applications like video calls, gaming, and financial trading. and transit dependency on any single ISPInternet Service Provider. A company that provides internet access to consumers and businesses, assigning public IP addresses and routing traffic to the wider internet. Examples include Comcast, AT&T, and SK Broadband..