IPTransit

IP transit is a type of Internet connectivity service in which a network provider offers global Internet reachability to a customer network by carrying its traffic to and from the Internet. The customer pays for bandwidth and the transit provider forwards the traffic by advertising the customer's IP prefixes to its upstream peers using the Border Gateway Protocol (BGP).

Typically, an edge router at the customer's site establishes one or more BGP sessions with the transit provider's routers. The provider then propagates the customer's prefixes to the Internet through its own network and upstream connections, enabling other networks to reach the customer and vice versa. The provider may offer additional routing policies, redundancy, and traffic engineering features to optimize performance.

IP transit is contrasted with IP peering, where networks exchange traffic directly, typically without payment, under settlement-free arrangements. Transit provides broader reach to networks not present in the customer's own routing domain and is commonly used for multi-homing, backup connectivity, or when rapid scale is required.

Pricing is usually bandwidth-based, measured in Mbps or Gbps, and billed monthly, with possible setup fees, port charges, and volume discounts. Many customers also purchase service level agreements (SLAs) covering uptime, latency, and throughput, and some providers offer per-prefix or per-route filtering to enforce routing policies.

Choosing a transit provider involves evaluating backbone stability, number of upstreams, latency, jitter, and customer support. Proper routing configuration and monitoring help ensure predictable performance and prevent routing issues such as suboptimal paths or blackholing.