Peering and transit
Every network reaches the rest of the internet in one of two ways, and knowing which explains most of what you see in a traceroute.
The two arrangements
- Transit
- You pay a carrier to carry your traffic to the whole internet. They announce your prefixes everywhere and give you a full routing table. Simple, universal, billed by volume or committed rate.
- Peering
- You exchange traffic directly with another network, usually without payment, and only for that network's own customers — not the rest of the internet. Shorter path, fewer hops, no middleman.
An internet exchange is the place peering happens: a shared switch fabric where hundreds of networks can reach each other with one port. AMS-IX in Amsterdam is one of the largest, which is a large part of why Amsterdam matters.
How a path gets chosen
BGP prefers, roughly in this order: the route with the highest local preference, then the shortest AS path, then the cheapest exit from the network. Local preference is set by the operator, which is why “shortest path” is not the rule people assume it is.
In practice: a network usually prefers a peer over transit, because peering is free and shorter. Which means the quality of your path depends on who your provider peers with — not on how much bandwidth they bought.
Why this matters to you
- A well-peered network reaches most European users in fewer hops, with fewer parties able to have a bad day in the middle.
- More paths means more options when one is congested. If a route to your users is poor, there is somewhere else to put it.
- Peering is not universal. Some networks peer with nobody and everything reaches them via transit, which is why a particular destination can be slow no matter what anyone does.
Asymmetry is normal
Traffic to you and traffic from you often take different paths, because each network makes its own choice independently. That is why a one-sided traceroute so often proves nothing, and why we ask for both directions — see reading a traceroute.
What we do
We run our own network with multiple upstream carriers and backbone connections, in a city where the alternatives are a cross-connect away. The routing is ours, which is the practically important part: when a path to your users is bad, we can change it rather than forward your ticket.
Send us an MTR from both ends and we will look at it — see routing problems.
If you want to do it yourself
With your own AS number and address space you can take transit from us and peer elsewhere, or multihome between providers. That is a real step up in control and in responsibility — see running BGP with us, multihoming and BGP communities.
Still stuck? Mail support@novogara.com — an engineer answers, at any hour. Back to the knowledge base