Internet Backbone Networks

The Internet backbone is a set of network connections owned by the largest Internet providers. These backbone networks are often called Tier 1 networks. A tier 1 network is an Internet provider which does not have to pay anyone else for IP transit. Instead the tier 1 network peers with other tier 1 networks and sells uplinks to smaller networks.

A network that makes up the backbone of the Internet is global is size and able to transfer traffic from one point of the world to another. There are close to 20 Tier 1 carriers around the world. Some own their own fiber optic connections that span continents and across oceans. Others lease the fiber but have their own routers and switches.

It is hard to say for certain who is a backbone and who is not because many companies do not publicly share who they have paid peering with and who they have settlement free peering with.

Every other network in the world buys IP transit from one of these 20 tier 1 networks, either directly or indirectly. The following is a list of these tier 1 networks which make up the backbone of the Internet.

Measuring Network Size

Measuring the size of a network is difficult. The proper criteria for deciding who the largest Internet network is is difficult. There are simply too many different ways to measure the size and reach of a network for there to be a consensus on the order of the top 20 networks.

Some advocate that the amount of bandwidth should be the best measure of network size. However, networks almost never reveal the amount of bandwidth they pass.

Others find that the amount of routes originating from a network is the best way to see who the largest network is. This makes sense. The larger the network the more routes would originate from within that network. This routing data is also publicly announced through the BGP protocol.

Because the number of routes announced is public, this is often the most common way to measuring network size. Other ways include the number of peers or the amount of income a company makes by selling transit.

These are all valid measures and each of them tells a slightly different story as to who the largest networks are. You can also take a look at the different network maps to see where they physically connect and have circuits.

Internet Backbone Networks

These are the networks that make up the Internet, in no particular order. They are identified with their ASN. This this the Autonomous System Number used to identify networks on the Internet. A single company may have multiple ASNs, but these are the main ones for each company.

The following data is collected from a number of sources, include and peeringDB. The Ipv4 and Ipv6 prefixes is from the recommended prefix peering limits on peeringDB.

The prefix originated numebrs are the amount of different sized prefixes that the network originates. That is, the Internet first learns those prefixes with that network.

The IPs originated (IPv4) shows the total amount of IPv4 addresses that the Internet learns from that network. The higher this number, the more end users there are in this network. In other words, the network is more likely to be an "eyeballs" network that has many home users. This is compared to a content network which does not have many end users but instead has content that the end-users might want to connect to (think of Google for example).

The BGP peers is the number of networks that the network is directly connected to. This is usualy set by the network's peering policy.

Level 3 (AS3356)

TeliaSonera (AS1299)

NTT (AS2914)

GTT (AS3257)

Cogent (AS174)

TATA (AS6453)

Verizon (AS701)

Telecom Italia Sparkle (AS6762)

Sprint (AS1239)

PCCW (AS3491)

China Telecom (AS4134)

Hurricane Electric (AS6939)

XO Communications (AS2828)

AT&T (AS7018)

Deutsche Telekom (AS3320)

KPN (AS286)

Orange (AS5511)

Telefonica Global Solutions (AS12956)

Zayo (AS6461)