Living Legend: Vint Cerf on the Internet and out-of-this-world communications

Vint Cerf wants to build the interplanetary Internet

Vint Cerf

Vint Cerf is one of the most recognized network engineers of all time. He is often referred to as one of the "fathers of the Internet" for his groundbreaking work as a co-designer of the TCP/IP protocols and the architecture of the Internet. He shares that title with colleague Robert E. Kahn. The two have been granted many prestigious awards for helping to build a technology that has arguably altered the course of human history more than any other. 

Honors heaped upon Cerf include the U.S. National Medal of Technology and the ACM Alan M. Turing award, the latter often referred to as the Nobel Prize of Computer Science. In addition to his role in building the Internet, Cerf is known for his decades of elbow grease of developing it, working at DARPA and then leading the Internet Corporation for Assigned Names and Numbers (ICANN) as chairman of the board from 2000-2007. He has participated in numerous other such organizations and as of 2011, his work is far from done. As Chief Internet Evangelist for today's 800-pound-gorilla, Google, Cerf is involved in projects that will extend the Internet's reach within our homes and beyond Earth.

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When you began, did you have a sense of how important your technology would become to the world?

I was a grad student at UCLA when a Request For Quotation was issued by the Defense Advanced Research Projects Agency, DARPA, for development of a packet switching network. Because of his early work on the statistical properties of message switching, Leonard Kleinrock, a member of the UCLA faculty, proposed to develop and operate a Network Measurement Center where measurements of the packet network would be made to test the predictive power of the queuing models that Kleinrock and his students were developing.

The first node of the ARPANET was installed at UCLA in September 1969. By the end of 1969 a four-node network had been established: UCLA, Stanford Research Institute (SRI), UC Santa Barbara (UCSB), and the University of Utah in Salt Lake City. Robert Kahn, one of the architects of the ARPANET, came to UCLA with his associate, David Walden, to run performance tests on the small network and to test theories that under certain conditions, the network could be made to "lock up."

I became the principal programmer for the Network Measurement Center run by Dr. Kleinrock. By 1972, the ARPANET had grown to about two dozen sites and had been publicly demonstrated at the International Conference on Computer Communication (ICCC). By that time, Douglas Engelbart's oN-Line System (NLS) was operating on the ARPANET and offered an extremely interactive, collaborative document creation, storage and retrieval. Electronic mail had been developed in 1971 or 1972. We were seeing 20 years into the future. Moreover, Xerox's Palo Alto Research Center had developed Ethernet in 1973 at the same time my colleagues and I were working on the Internet.

It was clear that this was a powerful and flexible way to mix information of all kinds into a single network. By 1988, I was convinced that this was incredibly powerful technology and that it would have to become a commercial enterprise if it was intended to be accessible to the general public. It was at this point that I was able to obtain permission to interconnect commercial traffic sources and sinks with the nascent Internet.

We knew we were working on an important network technology. Did I know it would become what people think of as the Internet today? Well that's hard to say. As early as 1988 (but 15 years into the program from my perspective) I had seen powerful exhibits and demonstrations of an internet at the famous Interop shows. It was at that time that I began to argue in favor of linking the U.S. Government Internet backbone to the Telenet, Tymnet, OnTyme and Compuserve networks. Once these were in place it was only a brief time before three commercial backbones emerges: PSINet (a spinout from the New York-based NYSERNET); UUNET (using UUCP protocols at first); and CERFNET. The advent of mobiles with Internet capability will see nearly ubiquitous use in the future.

Did you ever have an a-ha! moment while developing your technology?

I had a lot of them. Ray Tomlinson from BBN discovered that our first design lacked and needed a three-way handshake in order to distinguish the start of a new TCP connection from old random duplicate packets that showed up later from an earlier exchange. One aha moment was the earliest demonstration of the triple network Internet in July 1977. We did a demonstration where we were simulating someone in a mobile battlefield environment going across a continental network, then across an intercontinental satellite network, and then back into a wireline network to a major computing resource in national headquarters. Packets were traveling 94,000 miles round trip, as opposed to what would have been an 800-mile round trip directly on the ARPANET. We didn't lose one bit! After that exciting demonstration, we worked very hard on finalizing the protocols.

At what point did you start to realize the impact your technology would have?

Bob Kahn and I saw the enormous power of networking and in 1973 we wrote down our ideas for the design of an Internet (we did not call it that) that could interconnect an unlimited number of networks. By the mid-1980s there was a significant market for Internet-based products. The exponential growth of the Internet began in 1986 with the National Science Foundation's NSFNet. The NSFNet was originally designed to hook supercomputers together and was quickly outstripped by demand and was overhauled for T-1. When the NCP to TCP transition occurred in 1983 there were only 400 computers on the network. By January 1993 there were over 1.3 million computers in the system. There were only a handful of networks back in 1983; today there are millions.

In 1988 I made a conscious decision to pursue connection of the Internet to commercial electronic mail carriers. It wasn't clear that this would be acceptable from the standpoint of federal policy, but I thought that it was important to begin exploring the question. By 1989, an experimental mail relay was running at the Corporation for National Research Initiatives (CNRI) linking MCI Mail with the Internet through NSFNet. In the intervening two years, most commercial email carriers in the U.S. were linked to the Internet and many others around the world followed suit. In this same time period, commercial Internet service providers emerged from the collection of intermediate-level networks inspired and sponsored by the National Science Foundation as part of its NSFNet initiatives.

What technologies do you think will be important in the future?

If I knew that, I would be investing in it. But I think it's pretty clear that social networking will be a pretty big part of the next major consumer use of the Internet. The platforms that are available that allow people to create their own content and share it is probably the most important avenue. The next one will be this Internet of Things where we start managing collections of devices for our benefit.

The InterPlanetary Internet is also happening. During 2011, our initiative is to 'space qualify' the interplanetary protocols in order to standardize them and make them available to all the space-faring countries. If they choose to adopt the protocols, then potentially every spacecraft launched from that time on is potentially interwoven from a communications point of view. But perhaps more important, when the spacecrafts have finished their primary missions, if they are still functionally operable - they have power, computer, communications - they can become nodes in an interplanetary backbone. So what can happen over time is that we can literally grow an interplanetary network that can support both manned and robotic exploration.

Learn more about this topic

Why IPv6? Vint Cerf keeps blaming himself

Vint Cert on why TCP/IP was so long coming

Cerf: Future of Internet doesn't include an IPv7

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