AS Number

An AS Number (Autonomous System Number) is a fundamental part of routing topology on the Internet. It is used by high level routers to determine which router has been allocated various IP blocks. AS numbers are required when a company wishes to have migratable IP blocks that can be switched between multiple backbones. Having an AS number means that you can broadcast routes out to other routers on the Internet. This relationship makes up the core of the Internet. Having an AS number is a great responsibility as it gives you partial control over route advertising on the Internet.

Having a low AS number is considered somewhat of a prestige.

AS numbers in Bloomington

The following companies in Bloomington have AS numbers:

• AS87 INDIANA-AS -- Indiana University (Registered approximately in 1986. IU actually has several more, but its not clear where their routers are located)
• AS4279 INTERSOURCE - INTERSOURCE -- This was later Kiva Networking (now Egix, which has its own AS number as well). Aaron Peterson applied for this number on 1995-01-19
• AS11550 SDL-20-AS - Smithville Digital, LLC -- Smithville Digital / Bluemarble (registered 1998-09-30)
• AS19217 IVYTECHSC -- Ivy Tech Community College (registered 2000-12-05)
• AS22615 MONROECOUNTYCOMMSCH -- Monroe County Community School Corporation (Registered on 2001-10-25)
• AS40062 IBANKSYSTEMS -- Cornerstone Information Systems, Inc. (Registered on 2006-06-16)

As of 2009, there are only about 49,000 AS numbers registered worldwide out of a possible 65535 (although 64512-65535 are "private" and should never be seen on the Internet). So Bloomington holds a fair amount of its size. However in September 2008, IANA introduced 32-bit AS numbers, which allow for many more allocations than the original 16-bit number.

Trivia

• Purdue actually has a lower AS number (AS17) than IU, having registered it about 2 years prior. However IU was still the 28th institute of higher education out of more than 1500 to have an AS number worldwide.

External links

• Listing of AS numbers
• Wikipedia's article on AS numbers - A more detailed and technical explaination.