An internet exchange point (IXP) is shared network infrastructure where internet service providers, content and cloud networks, CDNs and some enterprises connect to exchange traffic directly with one another, a practice called peering. An IXP is usually an Ethernet switching fabric spread across one or more data centers in a metro area, run by a nonprofit association, a member-owned organization or a commercial operator. Exchanging traffic locally at an IXP gives networks shorter paths between each other and reduces the traffic they send through paid IP transit.
At a glance
- An IXP is a place and a platform: a shared switch, usually in carrier-neutral data centers, where networks meet to peer.
- Members connect a router port to the fabric and exchange routes with other members using BGP, either one-to-one or through route servers.
- Peering at an IXP reaches only the networks that peer with you there; it reduces IP transit, it doesn’t usually replace it.
- Joining typically requires your own autonomous system number, public IP space, a port fee and presence in, or a circuit to, an exchange location.
- Many businesses benefit from IXPs only indirectly, through how well their internet, cloud and CDN providers are peered.
What problem it solves
The internet is made of thousands of independent networks. If two of them in the same city have no direct connection, traffic between them may travel through a third network, sometimes in another city or country, and both pay a transit provider to carry it. That adds latency, cost and dependence on networks neither side controls.
An IXP gives many networks one place to connect. Instead of buying a separate private link to every network it exchanges traffic with, a member buys one port on the exchange and can peer with many others across it. Traffic between members stays local and on short paths, and the volume sent over transit goes down. For regions with little local exchange, IXPs also keep domestic traffic from being routed abroad and back.
How it works
Presence. A network places a router in, or brings a circuit into, a data center where the exchange has a switch. Large exchanges are distributed across several buildings in a metro, linked together. Connections to the exchange inside the building are usually a cross-connect through the meet-me room.
The fabric. The exchange assigns the member a port and an address on its shared network, usually a layer 2 Ethernet fabric. All members sit on that shared network.
Peering sessions. Members exchange routes using BGP, identified by their autonomous system numbers. They can set up bilateral sessions with individual peers or use the exchange’s route servers to peer with many members through one session. Each network decides whom to peer with and on what terms; some peer openly with everyone, others selectively.
Traffic exchange. Once routes are exchanged, traffic between those networks flows directly across the fabric. Traffic to networks not peering at the exchange continues to use transit.
Operations and routing security. Exchanges manage port capacity and monitor the fabric. Many filter route-server announcements, for example using RPKI and routing registries, though the controls vary by exchange.
When it matters for buyers
- When choosing an internet or cloud provider. Ask how well it is peered in your region; a well-peered provider often reaches popular services over shorter paths.
- When you run your own network. Organizations with their own ASN, multiple upstream providers and significant traffic to content or cloud networks may cut transit costs and improve paths by peering directly.
- When choosing a data center. Facilities that host major exchanges, often carrier hotels, give you more peering and carrier options from one location.
- When expanding into a new region. Local exchange density affects how traffic reaches users there.
Our data center interconnection overview covers how businesses connect to exchanges, carriers and partners in data centers.
Questions to ask vendors
- For an internet provider: which IXPs do you peer at in our region, and do you also have direct peering with the cloud and SaaS providers we use most?
- For an exchange: what port speeds, fees and contract terms do you offer, and are there membership charges?
- Which data centers host your switches, and what do cross-connects to them cost?
- Do you run route servers, and how do you filter route announcements?
- Which networks are members, and which of them peer openly through route servers?
- What is your fabric’s availability record and maintenance policy?
- Can we connect remotely through a carrier or reseller if we don’t have equipment in your buildings?
How it differs from IP transit
IP transit is a paid service in which a provider carries your traffic to and from the whole internet. Peering at an IXP is an exchange of traffic between two networks for their own routes, and usually their customers’, and it reaches only the networks you peer with. Networks that peer typically still buy transit for everything else; the exchange lowers how much traffic needs it. An IXP also differs from private interconnection, where two parties connect over a dedicated link between their equipment instead of over a shared fabric; networks with heavy traffic between them often move from exchange peering to a private link.
Problems this helps with
- Paying too much for IP transit when much of our traffic goes to a few big networks
- Traffic to a nearby network takes a long detour through another city
- Want more direct paths to content, cloud and eyeball networks
- Deciding which data center to put network equipment in
