What is an Internet Exchange Point (IXP)?
An Internet Exchange Point (IXP) is a physical location where multiple autonomous systems connect to exchange traffic directly, rather than routing through third-party transit providers. IXPs are critical infrastructure that improve performance, reduce costs, and keep local traffic local.
Why IXPs Exist
Without IXPs, a packet traveling from one network to another in the same city might have to route through a transit provider in another country. This adds latency, cost, and unnecessary distance. IXPs solve this by providing a neutral meeting point where networks can peer directly.
For example, if an ISP and a content provider are both connected to the same IXP, traffic between their customers flows directly through the exchange — often traversing just a single network switch — instead of taking a multi-hop path through expensive transit links.
How IXPs Work
An IXP operates a shared switching fabric — typically a large Ethernet switch or set of switches — in a carrier-neutral data center. Networks connect their routers to this fabric and establish BGP peering sessions with other connected networks.
There are two main peering models at an IXP:
- Bilateral peering — Two networks negotiate a direct BGP session between them. Each network chooses exactly which peers it wants to exchange routes with.
- Route server peering — The IXP operates a route server that acts as a BGP intermediary. Networks peer with the route server and automatically receive routes from all other participants, without needing individual sessions with each one.
Major IXPs
The largest IXPs handle terabits of traffic per second:
- DE-CIX Frankfurt (AS6695) — One of the world's largest by peak traffic, with over 1,100 connected networks
- AMS-IX Amsterdam (AS1200) — A major European exchange point
- LINX London (AS8714) — The London Internet Exchange
- Equinix exchanges — Operates IXPs in major cities worldwide
There are over 900 IXPs operating globally, from major hubs handling multiple terabits per second to small regional exchanges connecting local ISPs.
Impact on Routing
When networks peer at an IXP, the AS paths for traffic between them become shorter — often just two hops (your AS to their AS) instead of three or more via transit. This is visible in BGP looking glass results: networks with extensive peering tend to appear with shorter AS paths from many vantage points.
You can see this by looking up networks known for heavy peering, like Cloudflare (AS13335), which peers at over 300 IXPs worldwide and typically shows very short AS paths.