A Tier 1 network is an internet backbone that can reach every other network on the internet without buying IP transit from anyone. It does this through settlement-free peering, exchanging traffic with other large networks at no charge, and by selling transit to smaller networks. There is no official body that certifies Tier 1 status, and the term is used loosely in sales, so the claim is something to verify rather than take on trust.
At a glance
- The usual definition: a network that reaches the whole internet through peering and its own customers, with no paid transit.
- Tier 2 networks peer with some networks but also buy transit; Tier 3 networks buy most or all of their internet reach.
- There is no official list or certification; analysts and public routing data are the main evidence.
- Tier 1 status describes how a network is connected, not how well it will serve a particular site.
- It matters most to buyers of IP transit and less to a typical office internet buyer.
What problem it solves
The internet is a network of networks, and no single network connects to every other one directly. To reach the whole internet, a network either pays an upstream provider for transit or arranges peering with enough other networks to cover everything. The tier labels describe where a network sits in that hierarchy.
For buyers, the label is shorthand for a question that does matter: how many hops and how many intermediate providers does my traffic cross to reach its destination, and who controls them? A network with no upstream provider has fewer dependencies and more direct control over routing. The label is a starting point for that question, not an answer to it.
How it works
Settlement-free peering. Tier 1 networks exchange traffic with each other without payment, on the basis that each benefits roughly equally. They connect at many locations, typically through private interconnects and sometimes at internet exchange points (IXPs).
Selling transit. They sell transit to Tier 2 and Tier 3 networks, content providers and enterprises, carrying their traffic to the rest of the internet and announcing their routes.
Routing. All of this runs on Border Gateway Protocol (BGP). Each network is identified by an autonomous system number (ASN), and observed public routing data lets analysts infer which networks each one connects to, and so estimate tiers, though not every connection is visible.
Tier 2 and Tier 3. A Tier 2 network peers widely but buys transit for some destinations. A Tier 3 network, often a regional or local ISP, buys most of its internet reach from one or more upstream providers. Many Tier 2 networks have extensive peering and can deliver traffic as directly as a Tier 1 for many destinations.
A changing picture. Large cloud and content companies now run their own global backbones and peer directly with access networks, so much traffic never crosses a traditional Tier 1 network. The hierarchy is flatter than the tier labels suggest.
For help comparing transit providers, see our IP Transit solution page.
When it matters for buyers
- Buying IP transit for a data center or network. Transit providers’ upstream dependencies and peering affect reach, performance and resilience.
- Choosing two transit providers. Picking providers that do not depend on each other avoids a shared upstream failure.
- Evaluating performance claims. “Tier 1 network” in a proposal is a reason to ask for latency and routing data, not a substitute for it.
- Office or branch internet. For dedicated internet access, local access, SLA and support usually matter more than tier.
Questions to ask vendors
- Do you buy IP transit from any other network, in any region?
- Which networks do you peer with settlement-free, and where?
- What is your latency and routing to the cloud providers and applications we use most?
- How much capacity do you have to your major peers, and how do you handle congestion on those links?
- How many upstream providers would our traffic depend on, and which ones?
- If you are not Tier 1, what does your peering and transit mix look like?
How it differs from an ISP
An internet service provider (ISP) is any company that sells internet access, whatever its position in the hierarchy. A Tier 1 network is a specific kind of backbone that sits at the top of that hierarchy. Some Tier 1 networks also sell business internet directly, so your ISP can be Tier 1, but most ISPs are Tier 2 or Tier 3 networks that buy at least some transit from larger providers.