Microsoft Azure runs out of US IP addresses

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The lack of new IPv4 addresses in the US means Microsoft Azure is borrowing from elsewhere

Does your VM appear to be in Brazil when it's supposed to be in Microsoft's Azure datacenters in the US?

It hasn't absconded to be closer to the World Cup: Microsoft's Azure cloud service has run out of IPv4 addresses in the US, and it's borrowing from its Latin-American IP block.

The issue surrounds the shift from IP version 4 - which is running out of room - to IP version 6, which offers many more addresses.

Microsoft said that Azure customers may have noticed that virtual machines deployed in North America may act as though they're elsewhere, with web browsers bringing up international versions of a website, rather than the American one.

"IPv4 address space has been fully assigned in the United States, meaning there is no additional IPv4 address space available," said Ganesh Srinivasan, senior program manager, in a Microsoft blog post. "This requires Microsoft to use the IPv4 address space available to us globally for the addressing of new services."

"The result is that we will have to use IPv4 address space assigned to a non-US region to address services which may be in a US region," he said. "It is not possible to transfer registration because the IP space is allocated to the registration authorities by Internet Assigned Numbers Authority."

That means service may appear as though it's coming from a non-US location, though Microsoft stressed that the servers themselves remain in the US.

"It is important to note that the IP address registration authority does not equate to IP address physical location (i.e. you can have an IP address registered in Brazil but allocated to a device or service physically located in Virginia)," he said. "Thus when you deploy to a US region, your service is still hosted in US and your customer data will remain in the US."

Microsoft said it's working with IP databases to help deal with the issue. The company bought a tranche of IPv4 addresses three years ago for $7.5 million, but they don't appear to have lasted long.

Update: Microsoft has updated its blog post with the following statement, saying it "misstated the situation" around its IPv4 availability.

"Currently, Microsoft has IPv4 space in US regions. That said, inventory space is a dynamic situation. In the past some customers were assigned non-US IPv4 addresses as a result of limited inventory. We have already updated many major geo-location databases to ensure customers do not experience any confusion in the future. We apologise for any inconvenience this has caused."

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