Microsoft will play by the rules on legacy IPv4 addresses

The company originally bought 7 million slightly used addresses, but ARIN said the addresses are not available for private ownership

Microsoft in March paid $7.5 million for a block of nearly 7 million slightly used IPv4 addresses from Nortel, which is in U.S. Bankruptcy Court in Delaware. The purchase touched off a possible confrontation over who controls addresses issued before the current Regional Internet Registry for North America was created.


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With the specter of IPv4 address depletion now becoming a reality, there is a growing concern of a developing unregulated black market for remaining unused addresses that have been allocated. The concern is especially high for addresses allocated by organizations such as InterNIC (the Internet Network Information Center) before December 1997, when the American Registry for Internet Numbers (ARIN) was created.

ARIN said the addresses are not privately owned assets and should be transferred under its policies, which it says reflect the consensus of the Internet community. Although it has no contractual agreement with the holders of these legacy addresses, ARIN has assumed the responsibility for managing the addresses.

The Microsoft-Nortel deal was the first large scale transfer of legacy addresses since IPv4 space became scarce. A confrontation over whether these addresses would — or could — be transferred outside the ARIN framework was avoided in April when Microsoft reached an agreement with ARIN that the Nortel numbers would be placed under a registration services agreement for legacy numbers.

About the Author

William Jackson is freelance writer and the author of the CyberEye blog.

Reader Comments

Mon, May 2, 2011

The actual number of IP addresses bought was 666,624 for $7.5 million.

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