Talking about tiers
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Users will often hear terms such as "tier 1" or "tier 2" to describe an ISP. If you are like most folks these are not crystal clear definitions as to what type of service, support or infrastructure you will get if you subscribe to an Internet service from a tier 2 ISP over a tier 1 ISP.
While Network World has consciously avoided using this terminology because of its lack of clarity, here are some definitions from International Data Corp., a consulting firm in Framingham, Mass., to help you out when you do run into the ISP tiers.
A tier 1 ISP operates a national Internet backbone that supports at least 45M bit/sec at its core. These ISPs often sell wholesale service to local telephone companies as well as local ISPs. Tier 1 ISPs also specialize in selling dedicated access to business customers. Some tier 1 ISPs include AT&T WorldNet, UUNET (an MCI WorldCom company) and even smaller national ISPs such as Savvis.
Tier 2 ISPs in contrast do not have their own backbone, but lease capacity from other service providers. Tier 2 ISPs also typically support more than 100,000 customers. IDC puts America Online, Epoch Internet and Verio in the tier 2 category.
Tier 3 ISPs simply don't have national backbones, but instead only support a regional or local network. There are about 4,000 tier 3 ISPs according to IDC.
ISPs, especially the newly formed tier 1 ISPs, will often describe themselves as tiers. However, all that this really means is that they have national coverage and that they have a 45M bit/sec or faster backbone. And one thing that users should keep in mind is that these tier ratings are not issued by some sort of accredited organization. When an ISP believes they have the tier 1 criteria down they can simply add that tag to their boilerplate.
So instead, ask an ISP to name the cities they can offer dedicated Internet access to and how long it will take to get it and how fast their Internet backbone actually is. Because at this point 45M bit/sec really isn't that fast anymore.