Internet Protocol (IP) transit

Internet transit is a service which allows network traffic to cross a computer network and is generally used to connect smaller Internet Service Provider (ISP) to large internet. The internet is made up of a vast collection of networks and in order to get traffic from one user to another, all service providers need to have an interconnection mechanism.

The connections between two networks can be either direct or indirect. However, a majority of the connections are indirect as the providers do not have global network footprint and thus the traffic can be sent through different interconnections to reach the end user.

While this is not the complete list of the leading providers available worldwide, some of them are:

• AT&T
• NTT Communications
• CenturyLink
• XO Communications
• GTT
• Hurricane Electric
• Telefonica
• KPN
• Level 3
• TeliaSonera
• Sprint
• Tata Communications
• Cogent
• Verizon

You must have probably heard the term Tier-1, Tier-2 and Tier 3, but do you know what does it actually mean? A Tier-1 carrier possesses a network that participates solely on the internet via settlement free interconnection. It has a direct connection to the internet and uses the network to deliver voice and data services.

A tier-2 carrier operator gets a portion of the network from the tier-1 operator through the concept of peering. However, the tier-2 providers also need to purchase IP transit to reach some portion of the internet. Tier-2 providers are the most common type of providers as it is much easy to purchase transit from Tier-1 network as compared to the situation when you want to peer with them and then become Tier-1 carrier. The term Tier-3 is used to describe networks that purchase IP transit from other networks to reach the internet.