What Is Interconnection in Networking and How Does It Work?
Interconnection is the physical and logical linking of two or more networks so they can exchange traffic directly. It is the underlying mechanism that turns thousands of separately operated networks into the internet. A network uses interconnection when it needs to reach destinations outside its own infrastructure — and the choice of how to interconnect (transit, public peering, or private peering) determines its cost, performance, and control over routing.
The three main interconnection options
| Option | What it is | Typical use | Trade-off |
|---|---|---|---|
| Transit | A provider sells you access to the entire internet | Smaller networks, or any network needing full reach | You pay for capacity; routing is largely controlled by the provider |
| Public peering | Multiple networks connect at a shared Internet Exchange Point (IXP) and exchange traffic | Networks that want many peers through one port | Shared fabric; you peer with whoever is present and willing |
| Private peering | A direct, dedicated link between two networks | High-volume pairs, or networks wanting tighter control | Dedicated capacity and cost, but predictable performance |
These are not mutually exclusive. Most networks combine all three: transit for full reach, public peering for broad cost-effective coverage, and private peering for their heaviest traffic relationships.
Interconnection vs. transit vs. peering
The distinction matters because each solves a different problem.
- Transit is a commercial service. You buy a route to the whole internet from an upstream provider. It guarantees reachability but you pay for it, and the provider sits between you and the rest of the world.
- Peering is a settlement-free exchange between two networks that both benefit from the traffic. Each side accepts the other's routes and traffic directly. It reduces reliance on paid transit and can shorten the path traffic takes.
- Interconnection is the umbrella term for both. Transit and peering are two ways of interconnecting; the word describes the link itself, not the commercial arrangement.
A useful way to think about it: interconnection is the what, peering and transit are the how.
Why Internet Exchange Points matter
An Internet Exchange Point (IXP) is a physical location where many networks place equipment and connect to a shared switching fabric. Instead of building a separate link to every network it wants to reach, a network connects once to the IXP and can then peer with any other participant.
DE-CIX, for example, operates neutral Internet Exchanges across Europe, the Middle East, Africa, Asia, and the Americas, and describes its offering as premium interconnection services. "Neutral" here means the exchange itself does not compete with its customers for traffic — it provides the meeting point, not the connectivity.
The practical effect of an IXP:
- One port, many peers. A single connection can reach dozens or hundreds of networks.
- Lower latency. Traffic often takes a more direct path than it would through transit providers.
- Lower cost. Peering at an IXP can replace a meaningful share of paid transit.
- Resilience. Multiple peering relationships reduce dependence on any single path.
How networks decide where and how to interconnect
There is no single rule, but the decision usually weighs a few concrete factors:
- Traffic volume and direction. If a large share of your traffic goes to a specific network, a direct or private peering link becomes attractive. If traffic is spread across many networks, an IXP gives broader coverage per connection.
- Geography. Interconnecting close to where traffic originates or terminates reduces latency. This is why networks join IXPs in the regions they serve.
- Cost. Compare the price of transit capacity against the cost of a port at an IXP plus the effort of establishing peering relationships.
- Reach and redundancy. Transit provides full reach in one contract; peering requires building relationships network by network but gives more control and often better paths.
- Policy and willingness. Peering only happens when both networks agree. Larger networks are sometimes selective about whom they peer with, which is why transit remains necessary even for well-peered networks.
In practice, a network's interconnection strategy evolves: it may start on transit, add public peering as traffic grows, and establish private peering with its largest counterparts.
What this means if you are evaluating interconnection
If you are choosing how to connect, the question is not "peering or transit" but "which mix." Start by mapping where your traffic goes and where your users are. Then check which IXPs operate in those regions and which networks are present there. Transit covers the gaps that peering cannot. For most networks, the goal is to peer as much high-volume traffic as is practical and use transit for the rest — and an IXP is usually the most efficient place to make those peering connections happen.