Practical Technology

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NAT won’t save you from the need to switch to IPv6


Once upon a time, anyone could get a static Internet Protocol (IP) Class C /24 address. That meant you got 256 addresses, well actually since .0 and .255 are set aside, and one address was assigned to your gateway you actually had 253 addresses. But that was more than enough for most small businesses. That was then. This is now.

Today, ISPs don’t hand out Class C /24 addresses to just anyone. Instead, you’ll need to ask for one, and you’ll probably pay extra for it. Today’s SOHO default seems to be a Class C /30. That will give you 8 addresses, with again only five of them actually being usable. Yes, all your devices on that network can get to the Internet via NAT (Network Address Translation), but NAT is no more a permanent fix than using duct tape to seal a gas tank leak.

Sure, it will work fine for you for today, but what about tomorrow when you need more addresses? In the long run, as John Curran, president and CEO of ARIN (American Registry for Internet Numbers) explained, “Although NAT works fine for a single enterprise, ISPs know that NAT can’t be scaled indefinitely on the scale that they would require to continue to connect customers just via IPv4. This is why they’re looking to IPv6 to connect new customers. And while some carrier-scale NAT (between IPv6 and IPv4) will be used during transition to IPv6, we need to focus on making public web sites IPv6 reachable in order to keep the Internet running over the long-term.”

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