What is PeeringDB?

PeeringDB is a free public database where networks, Internet Exchanges and data centres publish the details other operators need to set up peering and filters.

Each network on PeeringDB has a record keyed by its ASN, maintained by the network itself. The record typically lists its peering policy (open, selective or restrictive), the exchanges and facilities where it is present along with its addresses on each exchange's peering LAN, contact details for its NOC and peering team, and suggested maximum-prefix limits for IPv4 and IPv6. One field matters especially for filtering: the IRR as-set/route-set, which names the AS-SET the network wants its neighbours to build filters from. Records for exchanges (IXs) list their peering LAN prefixes and members, and facility records list which networks and exchanges are in a building. PeeringDB is run as a non-profit and offers both a website and a public API.

In practice, engineers use PeeringDB when planning where to peer ("which networks are at this exchange?"), when setting up a new session ("what's their address on the IX LAN and their max-prefix?"), and when generating filters with tools like bgpq4. Many automation tools read it directly to configure exchange sessions. Keep in mind that it is self-reported: an out-of-date as-set or a max-prefix value that is far too low causes real outages, so keep your own record current whenever your network changes. PeeringDB is not a routing registry; the prefixes themselves still live in the IRR and in RPKI, and PeeringDB just points you to the right object. The IRR, RPSL and AS-SETs lesson shows how that as-set becomes a filter, and Setting up VyOS with basic BGP uses an exchange route server.