Network management Toolkit

Inventor celebrates 30 years of Ethernet

Tags:
30 Years,
Bob Metcalfe,
Years,
30

Paul Festa CNET News.com CNET News

Published: 21 May 2003 10:22 BST

But the Internet, or the Arpanet, preceded your description of Ethernet by a few years, and the first actual implementation of Ethernet technology by even longer. So my question is, how were messages transmitted before Ethernet?
The Internet had a preceding set of protocols, an earlier generation designed for a much smaller network. It was worldwide, but had a smaller number of hosts and was not designed to be used for connecting networks. So TCP/IP greatly expanded the network space and provided for building a network of networks, lots of LANs connected by lots of WANs.

How did the Ethernet prevail over the older protocols, and the others that cropped up in the future?
The speech I'm going to give on Thursday is called "Ethernet vs. Godzilla". The idea is that Ethernet has encountered a series of competitors out trying to kill it. The number is huge. The most famous is the IBM token ring. It was among the many Godzillas and the most formidable because it was backed by the dominant monopoly in computing at the time.

How was the token ring different from Ethernet? And what were its advantages and disadvantages compared with Ethernet?
It was developed by IBM. That was its principle advantage. It was organised around the passing of a token from station to station, so computers could take turns transmitting messages. With Ethernet, any station would transmit immediately and hopefully avoid collisions. The token gave permission to transmit a message. The advantage was what they called determinism, which I considered to be a red herring.

What did they mean by it?
It meant they could guarantee that data would be delivered in a certain amount of time. Without the token, in theory, Ethernet packet transmissions could take forever. That was smaller than the probability of the Earth blowing up, but they used to throw determinism at us.

So if the token ring worked with tokens, how does Ethernet work?
Any station wishing to send a packet would form the packet in memory, then listen to the ether -- the cable or the fibre or whatever -- to see if there were already a transmission ongoing. And if there were, it would wait, deferring to the transmission ongoing, and then it would send its packet. But it was possible that more than one station would be waiting, so then you would get a collision. It would notice that there was interference on the cable, which we called collision detection. As soon as it was detected, the station would abort transmission and choose a random number and try again a few microseconds later. The second one would defer and avoid multiple collisions.

And what happened to the token ring Godzilla?
There is a lot of token ring out there, but in the last few weeks IBM announced a $100m program to tear out token rings inside of IBM and replace them with Ethernet. That's a sign that you could declare it dead. Although it's been dead for some time, that would be the final blow. And the reason that Ethernet won was that Ethernet was an open standard with many competing companies providing it.

What strikes you most about what's become of Ethernet since your memo 30 years ago?
What Ethernet is today is more than a packet format or media access algorithm -- it is a business model.

How so?
I was hoping you'd ask that. There are four business models out there today. The first is the vertical model exemplified in the 1980s by the IBM monopoly. The second, which dominates today, is the horizontal model dominated by AOL, Cisco, Intel and Microsoft. They are also monopolies, I might add. The third is the Linux/open-source business model. And the fourth is the Ethernet business model.

It's based on de jure standards with proprietary implementations of those de jure standards, and it is unlike open source in that competitors don't give their intellectual property away. The competition is fierce, but there is a market ethic that products will be interoperable. And the standard evolves rapidly based on market engagement in such a way to value the installed base. There is a heavy value placed on sustaining and maintaining the installed base. That's the Ethernet business model.

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