Peeringiä

Peeringiä, usually referred to in English as peering, is the interconnection of two or more independent networks to exchange traffic between their customers. The arrangement is primarily about direct routing of end-user traffic rather than paying third-party transit providers. Peering can be settlement-free, where networks exchange traffic without per-traffic payments, or involve some form of compensation or credits in more complex arrangements.

Key elements of peering include the physical interconnection, routing policies, and the commercial terms governing the exchange. Networks typically connect at Internet Exchange Points (IXPs) using shared switching fabrics, or establish private, direct connections known as private peering. Routing uses the Border Gateway Protocol (BGP) to advertise reachability between networks, while policies control which routes are accepted and how traffic is balanced.

Types and practices vary. Settlement-free peering is common at IXPs, but paid peering or sponsorship arrangements also exist, especially where traffic exchange is uneven or strategic considerations apply. Peering agreements can be bilateral or governed by multi-lateral policies at an IXP. Open, selective, or restricted peering policies describe how permissive a network is in accepting peers.

Peering offers several benefits, including lower latency, higher throughput, improved reliability, and reduced dependence on third-party transit. It also provides more control over routing and performance. Risks include traffic imbalance, de-peering disruptions, technical complexity, and potential security concerns if route filtering and validation are not properly managed.

In practice, many networks operate a mix of settlement-free and paid peering, using IXPs and private connections to optimize performance and cost.