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Moving to IPv6: Rebuilding the Heart of the Internet Without Missing a Beat

Within the coming decade, Internet Protocol version 6 (IPv6) will be key to enabling 50 billion connections among people, processes, data, and things in the Internet of Everything (IoE)But how we get there from here is not a simple matter.

I’m very pleased to invite Mark Townsley, Cisco Fellow and recognized industry expert on IP, to discuss this important transition in the second of our three-part blog series on IPv6. The first blog in Mark’s series was “Demystifying IPv6”.

townsley

Three years ago, I organized a conference in Paris where I thought it would be fascinating to bring together the original designers of IPv6 alongside the engineers who were finally deploying it at scale more than a decade later. During this discussion, Steve Deering, one of the “fathers” of IPv6 in the 1990s, was asked one of the most common questions about IPv6: Why wasn’t it designed for backward compatibility with IPv4? After all, wouldn’t it be easier to make the transition if the two versions could transparently coexist? Steve answered that the problem is not that IPv6 wasn’t designed to be backward-compatible—the real problem is that IPv4 wasn’t designed to be forward-compatible.

Steve was making the point that IPv4 was designed with a fixed address space. Given the number of computers connected to the Arpanet throughout the 1970s, this fixed-length address field seemed to be sufficient—at least for that version of IP. IP had been replaced before, and it seemed perfectly reasonable at the time that it might be replaced again. Read More »

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