IP Transit Services | ISP Tiers – Tier 1, Tier 2, Tier 3


IP Transit Services | ISP Tiers – Tier 1, Tier 2, Tier 3

Depending on their size and requirements, organizations can connect to the Internet in a variety of ways including IP transit, peering, dedicated Internet access and mass market broadband access. In this article, I focus on IP transit and its use by Internet Service Providers (ISPs), business organizations and other entities. To put things in perspective, I will also briefly describe the structure of the Internet and the three tiers of ISPs.

Internet Service Provider Tiers – Tier 1, Tier 2 and Tier 3 ISPs

Today the Internet can be thought of as a giant network of interconnected networks using the same communication protocol – Transmission Control Protocol/Internet Protocol (TCP/IP). At the core of the Internet is an ultra-fast global optical Internet backbone. The Internet backbone is a network of the worlds largest networks peered together into a seamless single network. These are referred to as Tier1 network providers or Internet service providers.

A Tier 1 Internet provider can be defined as one that uses unpaid peering only to connect to the Internet. In peering, usually in carrier neutral datacenters or Internet Exchange Points (IXPs), the Tier 1 providers interconnect with each other to exchange Internet traffic. This arrangement is also referred to as settlement-free interconnection because no payment is required.

There are only about a dozen Tier 1 providers in the world but there are some Tier 2 providers that may claim to be Tier 1 ISPs. The bottom line is that if they don’t connect to the Internet by peering ONLY, then they are not Tier 1 providers.  The largest of the Tier 1 providers include Level3 (now CenturyLink), Cogent, Global Telecom and Technology (GTT), Telia Carrier, NTT Communications, Tata Communications and Telecom Italia Sparkle.

Lower on the ISP hierarchy are smaller Tier 2 providers. Tier 2 ISPs are not large enough to be admitted into the Tier 1 club. In other words they don’t have enough traffic to be considered peers of the Tier 1 providers. Consequently, Tier 2 providers peer with each other and/or buy IP transit from the Tier 1 providers.  Most local loop or last mile access network providers fall in this category. They include Vodafone (buys IP transit from Level 3, Telia Carrier et al), Comcast (buys Ip transit from Tata Communications and NTT America) and British Telecom (buys IP transit from Telia Carrier et al).

Tier 2 providers are not restricted to network providers. Some data center providers such as Amazon also fall in this category as well.

At the bottom of the ISP hierarchy are Tier 3 Internet service providers. They are small, typically local and connect to the Internet exclusively by purchasing IP transit from Tier 2 or directly from T1 providers.

What is IP transit and who uses it?

Unlike the connectivity used by individuals to access the Internet, such as dedicated Internet access or mass market broadband, IP transit is a special way of accessing the Internet. It does not only allow the subscriber to access the Internet, but also allow Internet traffic to pass through or “transit” through their equipment. Once your network is connected by IP transit, it becomes a constituent of the Internet – one of the network that makes up the network of networks.

Not only public ISPs purchase IP transit. Business organizations, schools and c
olleges, National Research and Educational Networks (NRENs), Financial institutions and other entities also purchase IP transit. In fact, any entity can buy IP transit from Tier 1 and Tier 2 ISPs or any other wholesale provider, provided they can get an Autonomous System Number (ASN). An ASN is required of any entity that wishes to connect their network to the Internet. An autonomous system can be defined as one that can exchange routing information with other neighboring autonomous systems. To request an ASN number, visit the American Registry for Internet Numbers (ARIN).

Why purchase IP transit from Tier 1 providers?

Any eligible entity has the option to purchase transit from any provider whether it is Tier 1 or Tier 2. Notwithstanding the advantages of buying transit directly from Tier 1 providers, some entities prefer Tier 2 providers for a number of reasons and cost is the one that is most frequently cited. But don’t be deterred by pricing before you do some homework to find out how much it real costs. Contact FiberGuide with your requirements and an agent can share some pricing information for both Tier 1 and Tier 2 providers. Following are some of the advantages of Tier 1 IP transit:

  • Higher data rates – for subscribers looking for higher data rate or to upgrade to higher data rate in future, most Tier 1 IP transit providers offer data rates from as low as 10Mbps to as high as 100Gbps.
  • Large numbers of global points of presence (PoPs) – Tier 1 providers have a large footprint and can be accessed in many geographical regions around the world
  • Connected to important content – most Tier 1 providers are connected to the largest content providers. By connecting with a Tier 1 provider, important content is accessible by going through fewer hops and therefore lower latency.

If you have specific requirements for transit, please complete the form on our IP transit page. For other connectivity requirements such as Internet T1, Ethernet, Business DSL and Business Cable, search GeoQuote.

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