What Is a Network in Interconnection and How Do Networks Connect?

A network, in the context of interconnection, is an independently operated system of connected devices and infrastructure that exchanges traffic with other networks. The operator controls its own routing decisions and is identified on the internet by an Autonomous System Number (ASN). Networks connect by exchanging routes and traffic — either directly through peering, through a paid transit provider, or by meeting many other networks at an Internet Exchange Point (IXP). The sections below explain the network types involved, how traffic is addressed between them, and what operators weigh when choosing where and with whom to interconnect.

Networks by role

Interconnection discussions usually distinguish networks by what they carry and whom they serve:

The same organization can operate more than one type. A large carrier may run access, transit, and content infrastructure at once, which changes its peering posture in each role.

How networks are identified and how traffic is routed

Every network that participates in global routing is identified by an Autonomous System Number (ASN). The network announces the IP address ranges it is responsible for, and other networks learn those routes through the Border Gateway Protocol (BGP).

The practical effect:

• A network announces its prefixes to its neighbors.
• Neighbors propagate those routes further, so every network builds a routing table of how to reach every prefix.
• When traffic is sent, each network forwards it to the next hop that its routing table says is best for that destination.
• The path traffic takes is therefore the result of many independent routing decisions, not a single central map.

This is why interconnection choices matter: they change which routes a network can use and how directly traffic reaches its destination.

How networks connect to each other

There are three common ways networks interconnect, and most operators use a mix:

Peering

Two networks agree to exchange traffic directly between themselves, typically without paying each other for the exchange. Peering can be private (a direct physical or virtual link between the two parties) or public (both parties connect to the same exchange fabric). Networks decide where to peer based on factors such as traffic volume, geographic proximity, cost, latency, and how much of their traffic goes to that partner.

Transit

A network buys connectivity from another network to reach the rest of the internet. Transit is the fallback that makes a network reachable even where it has no direct peering relationship. It is usually the paid option, in contrast to settlement-free peering.

Internet Exchange Points (IXPs)

An IXP is a shared physical and logical location where many networks connect to a common switching fabric and peer with each other. Joining one IXP can give a network many peering options through a single connection instead of building a separate link to every partner. DE-CIX operates neutral Internet Exchanges in Europe, the Middle East, Africa, Asia, and the Americas, and describes its services as premium interconnection services.

What networks consider when choosing interconnection partners or locations

The decision is usually a trade-off among measurable and strategic factors:

• Traffic volume and ratio — how much traffic flows each way between the two networks.
• Latency and path quality — whether a direct connection shortens the route to important destinations.
• Cost — port, cross-connect, transport, and any paid arrangement, weighed against the cost of transit.
• Reach — how many relevant networks, content sources, or end users are available at a given location.
• Redundancy — whether a new connection adds diversity or just duplicates an existing path.
• Operational effort — the work of configuring, monitoring, and maintaining each relationship.
• Neutrality and governance — whether the exchange or partner operates neutrally and under terms the network can accept.

Key terms to recognize

• Peering — direct traffic exchange between two networks, often settlement-free.
• Transit — paid connectivity that provides reach to the broader internet.
• IXP — a shared interconnection location where many networks meet.
• AS / ASN — an independently routed network and its identifying number.
• BGP — the routing protocol that exchanges reachability information between networks.
• Prefix — an IP address range a network announces and routes.

Understanding these terms is enough to follow most interconnection discussions and to evaluate why a given network peers where it does.