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Peering

A peering point is a physical location where multiple ISPs exchange Internet traffic with their peers in so-called peering arrangements. Most peering points are located in colocation centres, where the different network operators 'co-locate' their Points of Presence.

History of peering

In the early days of the Internet, a backbone network existed in the form of first the ARPANET and later the NSFNET. All other networks connected with one another via the backbone, and routing information was conveyed between the backbone and the other networks via the Exterior Gateway Protocol (EGP[?]).

With the decommissioning of the NSFNET Internet backbone network on April 30, 1995, the Internet now consists entirely of the various commercial ISPs and private networks, as connected at their peering points.

The Border gateway protocol (BGP) was designed to allow the different networks to exchange routing information, allowing them to route packets from network to network without needing any central authority to coordinate the operation of the Internet.

A neutral peering point or Internet exchange is a peering point that is independent of any single provider, and provides a commercially neutral venue for peering.

Not all peering happens at neutral peering points: private peering between large providers is very common, as is a customer-provider relationship, particularly at the bottom tiers of the Internet business. The latter is not a true peering relationship.

Peering agreements

Peering has three elements: the physical interconnection of the networks, technical liaison between the networks to allow exchange of routes, and the commercial and contractual peering agreements.

Providers with large traffic volumes can peer without charge with other large providers, often known as Tier 1 carriers.

Major public Internet exchanges include: