9 ms·

Ethernet will never work (1974)

120 points by pmarin 7y ago

timthorn 7y ago
Should be read in conjunction with https://web.archive.org/web/20080528221818/https://www.bytecoder.com/2008/05/25/xerox-1974-ethernet-would-be-a-failure-robert-bachrach-response/ https://web.archive.org/web/20080528221818/https://www.bytec...
willis936 7y ago
A human readable copy: https://web.archive.org/web/20080528224324/http://bytecoder.com/2006/09/28/xerox-1974-ethernet-would-be-a-failure/ https://web.archive.org/web/20080528224324/http://bytecoder....
elcomet 7y ago
Here's the text transcript for those who have a hard time reading this blurry document: To: Bob Metcalf and Dave Boggs Date: March 5, 1979 From R.E. Bachrach Location: PARC - Bldg. 31 Subect: Comments on "Draft Ethernet Overview" Organization: GSL - 44 I have read with dismay your presentation "Draft Ethernet Overview". As I am sure you are aware, technically or conceptually there is nothing new in your proposal. Perhaps appropriately, you have chosen a coined jargon utilizing discredited scientific conceptual expression in which to frame your ideas. I find your analysis on the proposed interconnection lacking in technical credibility. Quantitative statistical analysis would show that your proposed system would be a failure. You have tried to adopt a scheme inappropriate to the intended engineering application. A random transmission scheme such as you propose, along with the quasi-de-randomizing hardware you invoke to patch the obvious deficiency, would place in fact an undo hardware, software, and scheduling problem on the individual stations. You should seriously reconsider your basic premise and formulate fully and logically all the parameters necessary to evaluate the system. Your transmission medium or environment is not quantum noise limited. Simple analysis shows that imposing a poisson (i.e., random) statistics on message transmission drastically reduces the available effective bandwidth. Such a system is effective (reasonable) only in the limit of negligible average bit transmission rates. In fact you will want to maintain as high an effective transmission rate as possible. This requires a synchronized system. The fallacy in your conception is that the stations should be transmitting randomly. One possibility for a synchronized system would be time division multiplexing. You should seriously study how the telephone companies handle this problem. For example, the A.T.T Long lines T2 buried microwave link multiplexes close to 10^7 - 6 KHz channels. Most importantly, you should fully define your engineering application before proceeding further. You specify an undefined message packet length, a 1 mile or 1 mile diameter look and 256 stations working ad 3Mbs rate. What is the nature of the station? How many bits transmitted does an activity require and what is the expected average rate that the 256 stations will be seeking use of the bus in the contemplated application? What is a tolerable dead time for a given station to acquire a full set of data? The worst case delay for your 1 mile loop is 2~ usec. what effect dos this have on far stations getting locked out, etc. . . ? Robert Bachrach
- jeffadotio 7y ago
  The article seems to miss the concept of criticizing an idea without criticizing the individual. This approach is ineffective as a means of communication. It just looks like mud-slinging and it always comes off as a defense mechanism. Even when one is genuinely interested in addressing the issue this obscures that intent. Edit: Also, thank you for posting the text. I came to the comments hoping this had been done.
  - enneff 7y ago
    Sorry, where is the OP critiquing the individual? I can't see it.
  - justin66 7y ago
    Seventies-era Xerox PARC cultivated a deliberately confrontational environment for its researchers. They managed to accomplish some great things.
    - kondro 7y ago
      "They managed to accomplish some great things" in spite of being jerks to each other. Imagine what they could've accomplished if they had empathy and were collegial with each other.
      - Gibbon1 7y ago
        When you consider, other people took their ideas and build companies worth hundreds of billions out of them, but they themselves didn't. hmmm...
  - fogetti 7y ago
    Where was he criticizing the individual? I can't find it in the text
- lisper 7y ago
  And here's a follow-up he wrote in 2008: https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_xerox_parc_engineers_invented_ethernet/c043yl0/ https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_x... --- Appropriately, through a conversation with Comedian Wayne Cutter (http://www.waynecotter.com http://www.waynecotter.com) about Xerox PARC, I became aware in a Google search that my March 4, 1974 private Xerox Confidential Memo to Bob Metcalf and Dave Boggs was floating around the Internet and a major subject on numerous blogs. Unfortunately the role of my memo in the development of Ethernet II is not understood. Ethernet was the invention of Bob Metcalf and Dave Boggs as an outgrowth of Bob’s PhD thesis on the Aloha Net packet communications network. As is well documented, Xerox PARC from the beginning (1972-1974) was investigating distributed computing and several methods were in various stages of concept and feasibility development. I joined the Xerox PARC General Sciences Laboratory from Bell Laboratories in the summer of 1973 where I had worked on the first commercialization of light emitting diodes. At PARC our group was participating in the founding of the Stanford Synchrotron Radiation Laboratory. The prototype equipment we developed is now in the Smithsonian Museum. Part of this equipment was an advanced computer aided data acquisition system I developed. Although I am a condensed matter physicist, I was very interested in computers and software. I often hung out with the guys in the Computer Science Lab (one of whom recently visited the space station) which is how I received the first draft of Bob Metcalf’s and Dave Bogg’s technical paper describing their networking concept. (The team by the way was somewhat like Jobs and Wozniak in their respective contributions.) Our practice at the time, as it was at Bell Labs, was to have open and frank critique and internal review of technical papers before they were publicly released. It was in that spirit that I wrote my memo which only took on mythical proportions because CSL Lab Manager Bob Taylor chose to post it on his door. CSL at that time was something of a “hippy commune” and meetings were held with everyone lying around on bean bags. The first draft of the Ethernet I paper was written accordingly in a hip style. At the time I considered the draft quite an unprofessional document in addition to my technical concerns. I also at the time did not like the idea of naming a major new networking innovation after a discredited physics concept, the “ether”. The ether doesn’t exist and this was a real network on a real baseband coaxial cable medium. At the time of Ethernet I, packet collision detection was done in software with a CRC check of each packet. Detection of damaged packets would trigger staged random backoff until the valid packet was received. Following the “memo”, Bob Metcalf, Dave Boggs and I got together and had an extensive technical discussion of their paper on Ethernet I and its limitations. In that meeting I introduced them to the collision detection techniques used in pulse counting apparatus such as I used in my photon counting spectroscopic equipment at Bells Labs and at SSRL.1 Basically the receiver detection is an analogue to digital conversion and by suitable discrimination, one can distinguish between on and two pulse events. If two packets collided on the Ethernet cable at the tranceiver, then the receiver could determine that the pulse signal was wrong. The outcome of this discussion was Ethernet II. The Ethernet II hardware collision detection incorporated into the transceiver resulted from this discussion and transformed the networking capability and resolved many of the concerns I raised in my memo. Hardware collision detection enables an Ethernet communication channel to achieve effective utilization while limiting the system overhead and paved the way for Ethernet’s future success as we know it today. So to all the blogger’s out there, I was not a “Xerox Executive”, I was a member of the technical staff contributing to the fertile discussion in a very creative multi-disciplinary lab. I have grown to like the name Ethernet because of what has been accomplished. I don’t even mind all the other subsequent packet communication techniques that call themselves XXX-Ethernet and aren’t. So you should now switch your attention to Liveboard, a PARC invention pioneered by John Seeley Brown. Liveboard in the mid ‘80’s envisioned large flat panel interactive networked computer displays which could be used for group meetings and networked meetings. Through my work at Applied Materials over the last 17 years, we have created the ability to cost effectively manufacture such large LCD flat panel displays. LCD-TV and Computer Displays of 65”, 75”, and 108” are now entering mass production by our customers. Soon they will be in homes, offices, class-rooms and enumerable public spaces. These Liveboard displays will now be connected by Ethernet and also be lit by light emitting diodes whose commercialization I also helped pioneer. Every time you look at your computer display, you are looking at technology I helped to create and enabled it’s volume manufacturing. In case you didn’t know. LCD displays are enabled by amorphous silicon transistors, another technology pioneered at Xerox PARC and commercialized by Applied Materials manufacturing equipment.. R.Z. Bachrach, Memorial Day Weekend, 2008. CAnonymous@earthlink.net R. Z. Bachrach, Rev. Sci. Inst., 43, 734 (1972), "A Photon Counting Apparatus for Kinetic and Spectral Measurements."
QuesnayJr 7y ago
Bachrach gave an account of writing the memo on Reddit: https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_xerox_parc_engineers_invented_ethernet/ https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_x... According to his account, the original version of Ethernet had the problems he outlined in his memo, but in response the Ethernet designers made changes to account for them.
- rusk 7y ago
  I had a feeling that this wasn’t just some dummy prig (of which we are so accustomed nowadays)... I was curious reading through his critique how these issues were actually addressed or mitigated given the fact that ethernet ended up actually succeeding so well!
- jcrawfordor 7y ago
  Bachrach was also, basically, correct. The collision contention issue with Ethernet did limit the effective throughput of networks, which is why we now exclusively use Ethernet in configurations in which there is no collision contention (star topology, full duplex links). While his delivery is a bit harsh I think Bachrach's criticism was completely valid. As a matter which is perhaps more product than technical, Ethernet's downside resulting from collisions turned out to be an acceptable tradeoff for its other advantages (including simplicity and low cost compared to the non-collision systems of the time). However, it was indeed a significant limitation, and so continued development of Ethernet has had to find ways to eliminate the problem.
  - kortex 7y ago
    Except wireless internet used/uses a similar backoff trick, since a wireless channel is just like a hub. I'm not hip on the latest tech, but I think they use things like collision avoidance now.
    - chaorace 7y ago
      IIRC, newer wireless tech uses MIMO to work around the problem. Multiple radios operating on multiple wavelengths with devices taking turns round-robin style. Basically, and somewhat ironically, we've gone back full circle to time division multiplexing.
ColinWright 7y ago
From the middle of that thread[0] we discover that the original author of the original memo commented on it in 2008[1]. That follow-up is definitely worth reading to better understand the context of the memo. Not reading the follow-up and still criticising/laughing at the original memo is thoroughly unjust. I've submitted[2] the follow-up as a separate item if people want to comment on it. [0] https://twitter.com/_space_train/status/1236373295429226496 https://twitter.com/_space_train/status/1236373295429226496 [1] https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_xerox_parc_engineers_invented_ethernet/c043yl0/ https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_x... [2] https://news.ycombinator.com/item?id=22517640 https://news.ycombinator.com/item?id=22517640
- tyingq 7y ago
  That's certainly helpful. However, both the original memo, and the reddit update have the same sort of condescending/arrogant tone. That probably was as much a factor in why people jumped to conclusions as anything else.
  - deleted 7y ago
    [deleted]
  - fogetti 7y ago
    The reddit reply is neither condescending or arrogant. Why do you think so?
    - tyingq 7y ago
      The reply is certainly less abrasive than the original memo. I still feel the undertones, but that's my opinion and subjective. I feel it's still self aggrandizing and dismissive of Metcalf's work.
      - saber6 7y ago
        To put it into another context: I know very much about Mr. Metcalf's work. This other guy, I have never heard of him.
jmartrican 7y ago
I think the issue with this memo is not the technical concerns, but the insulting adjectives used in it. I cant imagine communicating with colleagues like that now a days. If you got technical concerns just point them out in a bullet list and leave the negative remarks out.
- melq 7y ago
  I understand where you’re coming from regarding the tone of the memo, but I think it’s important to keep in mind that this was not a public critique. The author mentions in a reddit post that this was originally a confidential internal document, and written in the context of a very small group of like minded coworkers who knew each other personally. I have certainly said or written things to coworkers of mine, who I count as respected friends and confidants, that if taken out of context and published for all to read would sound obnoxious if not reprehensible. The author had no idea that this private critique would be read by the general public 40 years later.
  - distances 7y ago
    Check the comment from the original presentation's author too. Apparently Bachrach didn't send this memo to him, but to the boss of his boss. I'm happy I've never had to work in an environment as hostile as that.
compsciphd 7y ago
I remember having a conversation with my dead 1-2 decades ago about switched ethernet. he was involved in network protocol development back in the 70s and was very familiar with AlohaNet and how ethernet borrowed from it. but had moved in a different direction in the decades since When I mentioned switched ethernet, he looked at me blankly and said something along the lines of (take some of it as hyperbole). "that's not ethernet? the whole point of ethernet is dealing with collisions. it's not ethernet without a medium where colluions can happen. heck, if we could have given everyone a private link, networking would have been easy"
deleted 7y ago
[deleted]
tedunangst 7y ago
Oh, wow, he misspelled undue. What a freaking moron!
- asveikau 7y ago
  When I read old text I frequently note that this sort of typo seems more common in the 70s. There was likely nothing checking the spelling. And certainly no editors putting squigglies. No place to Google your spelling doubts. And annoying to correct typewriter mistakes. Also, "undo" is a valid dictionary word.
linsomniac 7y ago
Back in the early '90s I used some network that ran over CAT-3 copper, and they had some sort of time slot so there were no collisions. I wish I could remember the name. Our Netware admin swore by it, because no collisions! IIRC, the throughput was 200kbps. It was, basically unusuable. We eventually switched our development network (8 machines) and customer network (25 machines) over to 10-base-2 Ethernet, and it was blazing in comparison. The Netware guy was sure it would be terrible because of the collisions. This memo reminds me a bit of that: in theory the other network was better, but in the real world Ethernet worked pretty well.
newshorts 7y ago
Sounds like he knew what he was talking about... I didn’t get “Ethernet will never work” from this memo, I got “you have some serious flaws you need to fix first.” Maybe it was the tone that made people jump on this. I can tell you, I appreciate the candor of someone willing to call you out like this before you go down the rabbit hole of mistakes you’re about to make.
justin66 7y ago
The funniest part about these tone police comments is that people are concerned about somebody hurting Bob Metcalfe's feelings.
agoodthrowaway 7y ago
So crazy that so many things came out of particle physics experiments: Ethernet, WWW, ... kind of crazy
tyingq 7y ago
There's an interesting interview where Metcalf shares his memory of the memo. An excerpt: "Metcalfe: My mom used to say if you can’t say something nice about someone you should just hold your tongue. But Bachrach was a not nice person. Or is for that matter; he may still be around for all I know. He was sort of a grouchy physicist on another floor in another lab, and he read my memo. And this is a physicist. The phrase you didn’t catch in his now famous memo -- this memo’s posted all over the world because everyone thinks it’s a hoot that he wrote this memo -- he said the problem with Ethernet was that it was not quantum noise limited, which is a very physicist thing to say. Of course it’s not quantum noise limited! That wasn’t the point. But he resented the fact that we were not using every shred of bandwidth that was capable. I told you how we decided on the clock speed. There were gigabits per second of capacity on that cable, and we were using a pitiful few megabits of it. But he was concerned that it wasn’t... And he did a nasty thing, and it was sort of an early lesson in nastiness, which is he wrote a memo. He didn’t come see me. He didn’t say, “I just read your memo and I have a few questions about it”. He didn’t do that. He sent a memo to my boss’s boss accusing me of writing something that wasn’t new and it wasn’t quantum [noise limited], completely making an idiot of himself. But it didn’t feel that way at the time. It felt kind of nasty. The next thing I know I’m in my boss’s boss’s office having to explain how this guy’s an idiot. Which he is, or was. To put it more kindly, he was from a different universe. I was in a computer science universe, he was in a physics universe. We were solving different problems and he should have minded his own business. Or at least come talk to me before sending a memo to my boss’s boss, so maybe I could save him the embarrassment. There are many places where I go where that memo is on the wall, pinned to some cubicle -- “the old Bachrach memo” -- because it’s just such a great example. Now Bachrach, I ran into him a decade or two after that unfortunate memo, whereupon he was letting it be known that he’d helped invent Ethernet. How he got there I don’t quite know, but it had something to do with this memo being really instrumental in fixing some of the early problems with Ethernet, which is a complete hallucination." http://archive.computerhistory.org/resources/text/Oral_History/Metcalfe_Robert_1/Metcalfe_Robert_1_2.oral_history.2006.7.102657995.pdf http://archive.computerhistory.org/resources/text/Oral_Histo...
himinlomax 7y ago
Note that what we now call Ethernet does not work like this (CSMA/CD) any more, now that we exclusively use switches instead of passive hubs. Wifi does, though.

120 points by pmarin 7y ago

Should be read in conjunction with https://web.archive.org/web/20080528221818/https://www.bytecoder.com/2008/05/25/xerox-1974-ethernet-would-be-a-failure-robert-bachrach-response/ https://web.archive.org/web/20080528221818/https://www.bytec...

willis936 7y ago

A human readable copy: https://web.archive.org/web/20080528224324/http://bytecoder.com/2006/09/28/xerox-1974-ethernet-would-be-a-failure/ https://web.archive.org/web/20080528224324/http://bytecoder....

elcomet 7y ago

Here's the text transcript for those who have a hard time reading this blurry document: To: Bob Metcalf and Dave Boggs Date: March 5, 1979 From R.E. Bachrach Location: PARC - Bldg. 31 Subect: Comments on "Draft Ethernet Overview" Organization: GSL - 44 I have read with dismay your presentation "Draft Ethernet Overview". As I am sure you are aware, technically or conceptually there is nothing new in your proposal. Perhaps appropriately, you have chosen a coined jargon utilizing discredited scientific conceptual expression in which to frame your ideas. I find your analysis on the proposed interconnection lacking in technical credibility. Quantitative statistical analysis would show that your proposed system would be a failure. You have tried to adopt a scheme inappropriate to the intended engineering application. A random transmission scheme such as you propose, along with the quasi-de-randomizing hardware you invoke to patch the obvious deficiency, would place in fact an undo hardware, software, and scheduling problem on the individual stations. You should seriously reconsider your basic premise and formulate fully and logically all the parameters necessary to evaluate the system. Your transmission medium or environment is not quantum noise limited. Simple analysis shows that imposing a poisson (i.e., random) statistics on message transmission drastically reduces the available effective bandwidth. Such a system is effective (reasonable) only in the limit of negligible average bit transmission rates. In fact you will want to maintain as high an effective transmission rate as possible. This requires a synchronized system. The fallacy in your conception is that the stations should be transmitting randomly. One possibility for a synchronized system would be time division multiplexing. You should seriously study how the telephone companies handle this problem. For example, the A.T.T Long lines T2 buried microwave link multiplexes close to 10^7 - 6 KHz channels. Most importantly, you should fully define your engineering application before proceeding further. You specify an undefined message packet length, a 1 mile or 1 mile diameter look and 256 stations working ad 3Mbs rate. What is the nature of the station? How many bits transmitted does an activity require and what is the expected average rate that the 256 stations will be seeking use of the bus in the contemplated application? What is a tolerable dead time for a given station to acquire a full set of data? The worst case delay for your 1 mile loop is 2~ usec. what effect dos this have on far stations getting locked out, etc. . . ? Robert Bachrach

jeffadotio 7y ago
The article seems to miss the concept of criticizing an idea without criticizing the individual. This approach is ineffective as a means of communication. It just looks like mud-slinging and it always comes off as a defense mechanism. Even when one is genuinely interested in addressing the issue this obscures that intent. Edit: Also, thank you for posting the text. I came to the comments hoping this had been done.
- enneff 7y ago
  Sorry, where is the OP critiquing the individual? I can't see it.
- justin66 7y ago
  Seventies-era Xerox PARC cultivated a deliberately confrontational environment for its researchers. They managed to accomplish some great things.
  - kondro 7y ago
    "They managed to accomplish some great things" in spite of being jerks to each other. Imagine what they could've accomplished if they had empathy and were collegial with each other.
    - Gibbon1 7y ago
      When you consider, other people took their ideas and build companies worth hundreds of billions out of them, but they themselves didn't. hmmm...
- fogetti 7y ago
  Where was he criticizing the individual? I can't find it in the text
lisper 7y ago
And here's a follow-up he wrote in 2008: https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_xerox_parc_engineers_invented_ethernet/c043yl0/ https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_x... --- Appropriately, through a conversation with Comedian Wayne Cutter (http://www.waynecotter.com http://www.waynecotter.com) about Xerox PARC, I became aware in a Google search that my March 4, 1974 private Xerox Confidential Memo to Bob Metcalf and Dave Boggs was floating around the Internet and a major subject on numerous blogs. Unfortunately the role of my memo in the development of Ethernet II is not understood. Ethernet was the invention of Bob Metcalf and Dave Boggs as an outgrowth of Bob’s PhD thesis on the Aloha Net packet communications network. As is well documented, Xerox PARC from the beginning (1972-1974) was investigating distributed computing and several methods were in various stages of concept and feasibility development. I joined the Xerox PARC General Sciences Laboratory from Bell Laboratories in the summer of 1973 where I had worked on the first commercialization of light emitting diodes. At PARC our group was participating in the founding of the Stanford Synchrotron Radiation Laboratory. The prototype equipment we developed is now in the Smithsonian Museum. Part of this equipment was an advanced computer aided data acquisition system I developed. Although I am a condensed matter physicist, I was very interested in computers and software. I often hung out with the guys in the Computer Science Lab (one of whom recently visited the space station) which is how I received the first draft of Bob Metcalf’s and Dave Bogg’s technical paper describing their networking concept. (The team by the way was somewhat like Jobs and Wozniak in their respective contributions.) Our practice at the time, as it was at Bell Labs, was to have open and frank critique and internal review of technical papers before they were publicly released. It was in that spirit that I wrote my memo which only took on mythical proportions because CSL Lab Manager Bob Taylor chose to post it on his door. CSL at that time was something of a “hippy commune” and meetings were held with everyone lying around on bean bags. The first draft of the Ethernet I paper was written accordingly in a hip style. At the time I considered the draft quite an unprofessional document in addition to my technical concerns. I also at the time did not like the idea of naming a major new networking innovation after a discredited physics concept, the “ether”. The ether doesn’t exist and this was a real network on a real baseband coaxial cable medium. At the time of Ethernet I, packet collision detection was done in software with a CRC check of each packet. Detection of damaged packets would trigger staged random backoff until the valid packet was received. Following the “memo”, Bob Metcalf, Dave Boggs and I got together and had an extensive technical discussion of their paper on Ethernet I and its limitations. In that meeting I introduced them to the collision detection techniques used in pulse counting apparatus such as I used in my photon counting spectroscopic equipment at Bells Labs and at SSRL.1 Basically the receiver detection is an analogue to digital conversion and by suitable discrimination, one can distinguish between on and two pulse events. If two packets collided on the Ethernet cable at the tranceiver, then the receiver could determine that the pulse signal was wrong. The outcome of this discussion was Ethernet II. The Ethernet II hardware collision detection incorporated into the transceiver resulted from this discussion and transformed the networking capability and resolved many of the concerns I raised in my memo. Hardware collision detection enables an Ethernet communication channel to achieve effective utilization while limiting the system overhead and paved the way for Ethernet’s future success as we know it today. So to all the blogger’s out there, I was not a “Xerox Executive”, I was a member of the technical staff contributing to the fertile discussion in a very creative multi-disciplinary lab. I have grown to like the name Ethernet because of what has been accomplished. I don’t even mind all the other subsequent packet communication techniques that call themselves XXX-Ethernet and aren’t. So you should now switch your attention to Liveboard, a PARC invention pioneered by John Seeley Brown. Liveboard in the mid ‘80’s envisioned large flat panel interactive networked computer displays which could be used for group meetings and networked meetings. Through my work at Applied Materials over the last 17 years, we have created the ability to cost effectively manufacture such large LCD flat panel displays. LCD-TV and Computer Displays of 65”, 75”, and 108” are now entering mass production by our customers. Soon they will be in homes, offices, class-rooms and enumerable public spaces. These Liveboard displays will now be connected by Ethernet and also be lit by light emitting diodes whose commercialization I also helped pioneer. Every time you look at your computer display, you are looking at technology I helped to create and enabled it’s volume manufacturing. In case you didn’t know. LCD displays are enabled by amorphous silicon transistors, another technology pioneered at Xerox PARC and commercialized by Applied Materials manufacturing equipment.. R.Z. Bachrach, Memorial Day Weekend, 2008. CAnonymous@earthlink.net R. Z. Bachrach, Rev. Sci. Inst., 43, 734 (1972), "A Photon Counting Apparatus for Kinetic and Spectral Measurements."

QuesnayJr 7y ago

Bachrach gave an account of writing the memo on Reddit: https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_xerox_parc_engineers_invented_ethernet/ https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_x... According to his account, the original version of Ethernet had the problems he outlined in his memo, but in response the Ethernet designers made changes to account for them.

rusk 7y ago
I had a feeling that this wasn’t just some dummy prig (of which we are so accustomed nowadays)... I was curious reading through his critique how these issues were actually addressed or mitigated given the fact that ethernet ended up actually succeeding so well!
jcrawfordor 7y ago
Bachrach was also, basically, correct. The collision contention issue with Ethernet did limit the effective throughput of networks, which is why we now exclusively use Ethernet in configurations in which there is no collision contention (star topology, full duplex links). While his delivery is a bit harsh I think Bachrach's criticism was completely valid. As a matter which is perhaps more product than technical, Ethernet's downside resulting from collisions turned out to be an acceptable tradeoff for its other advantages (including simplicity and low cost compared to the non-collision systems of the time). However, it was indeed a significant limitation, and so continued development of Ethernet has had to find ways to eliminate the problem.
- kortex 7y ago
  Except wireless internet used/uses a similar backoff trick, since a wireless channel is just like a hub. I'm not hip on the latest tech, but I think they use things like collision avoidance now.
  - chaorace 7y ago
    IIRC, newer wireless tech uses MIMO to work around the problem. Multiple radios operating on multiple wavelengths with devices taking turns round-robin style. Basically, and somewhat ironically, we've gone back full circle to time division multiplexing.

ColinWright 7y ago

From the middle of that thread[0] we discover that the original author of the original memo commented on it in 2008[1]. That follow-up is definitely worth reading to better understand the context of the memo. Not reading the follow-up and still criticising/laughing at the original memo is thoroughly unjust. I've submitted[2] the follow-up as a separate item if people want to comment on it. [0] https://twitter.com/_space_train/status/1236373295429226496 https://twitter.com/_space_train/status/1236373295429226496 [1] https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_xerox_parc_engineers_invented_ethernet/c043yl0/ https://www.reddit.com/r/reddit.com/comments/1xz13/in_1974_x... [2] https://news.ycombinator.com/item?id=22517640 https://news.ycombinator.com/item?id=22517640

tyingq 7y ago
That's certainly helpful. However, both the original memo, and the reddit update have the same sort of condescending/arrogant tone. That probably was as much a factor in why people jumped to conclusions as anything else.
- deleted 7y ago
  [deleted]
- fogetti 7y ago
  The reddit reply is neither condescending or arrogant. Why do you think so?
  - tyingq 7y ago
    The reply is certainly less abrasive than the original memo. I still feel the undertones, but that's my opinion and subjective. I feel it's still self aggrandizing and dismissive of Metcalf's work.
    - saber6 7y ago
      To put it into another context: I know very much about Mr. Metcalf's work. This other guy, I have never heard of him.

jmartrican 7y ago

I think the issue with this memo is not the technical concerns, but the insulting adjectives used in it. I cant imagine communicating with colleagues like that now a days. If you got technical concerns just point them out in a bullet list and leave the negative remarks out.

melq 7y ago
I understand where you’re coming from regarding the tone of the memo, but I think it’s important to keep in mind that this was not a public critique. The author mentions in a reddit post that this was originally a confidential internal document, and written in the context of a very small group of like minded coworkers who knew each other personally. I have certainly said or written things to coworkers of mine, who I count as respected friends and confidants, that if taken out of context and published for all to read would sound obnoxious if not reprehensible. The author had no idea that this private critique would be read by the general public 40 years later.
- distances 7y ago
  Check the comment from the original presentation's author too. Apparently Bachrach didn't send this memo to him, but to the boss of his boss. I'm happy I've never had to work in an environment as hostile as that.

compsciphd 7y ago

I remember having a conversation with my dead 1-2 decades ago about switched ethernet. he was involved in network protocol development back in the 70s and was very familiar with AlohaNet and how ethernet borrowed from it. but had moved in a different direction in the decades since When I mentioned switched ethernet, he looked at me blankly and said something along the lines of (take some of it as hyperbole). "that's not ethernet? the whole point of ethernet is dealing with collisions. it's not ethernet without a medium where colluions can happen. heck, if we could have given everyone a private link, networking would have been easy"

deleted 7y ago

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tedunangst 7y ago

Oh, wow, he misspelled undue. What a freaking moron!

asveikau 7y ago
When I read old text I frequently note that this sort of typo seems more common in the 70s. There was likely nothing checking the spelling. And certainly no editors putting squigglies. No place to Google your spelling doubts. And annoying to correct typewriter mistakes. Also, "undo" is a valid dictionary word.

linsomniac 7y ago

Back in the early '90s I used some network that ran over CAT-3 copper, and they had some sort of time slot so there were no collisions. I wish I could remember the name. Our Netware admin swore by it, because no collisions! IIRC, the throughput was 200kbps. It was, basically unusuable. We eventually switched our development network (8 machines) and customer network (25 machines) over to 10-base-2 Ethernet, and it was blazing in comparison. The Netware guy was sure it would be terrible because of the collisions. This memo reminds me a bit of that: in theory the other network was better, but in the real world Ethernet worked pretty well.

newshorts 7y ago

Sounds like he knew what he was talking about... I didn’t get “Ethernet will never work” from this memo, I got “you have some serious flaws you need to fix first.” Maybe it was the tone that made people jump on this. I can tell you, I appreciate the candor of someone willing to call you out like this before you go down the rabbit hole of mistakes you’re about to make.

justin66 7y ago

The funniest part about these tone police comments is that people are concerned about somebody hurting Bob Metcalfe's feelings.

agoodthrowaway 7y ago

So crazy that so many things came out of particle physics experiments: Ethernet, WWW, ... kind of crazy

tyingq 7y ago

There's an interesting interview where Metcalf shares his memory of the memo. An excerpt: "Metcalfe: My mom used to say if you can’t say something nice about someone you should just hold your tongue. But Bachrach was a not nice person. Or is for that matter; he may still be around for all I know. He was sort of a grouchy physicist on another floor in another lab, and he read my memo. And this is a physicist. The phrase you didn’t catch in his now famous memo -- this memo’s posted all over the world because everyone thinks it’s a hoot that he wrote this memo -- he said the problem with Ethernet was that it was not quantum noise limited, which is a very physicist thing to say. Of course it’s not quantum noise limited! That wasn’t the point. But he resented the fact that we were not using every shred of bandwidth that was capable. I told you how we decided on the clock speed. There were gigabits per second of capacity on that cable, and we were using a pitiful few megabits of it. But he was concerned that it wasn’t... And he did a nasty thing, and it was sort of an early lesson in nastiness, which is he wrote a memo. He didn’t come see me. He didn’t say, “I just read your memo and I have a few questions about it”. He didn’t do that. He sent a memo to my boss’s boss accusing me of writing something that wasn’t new and it wasn’t quantum [noise limited], completely making an idiot of himself. But it didn’t feel that way at the time. It felt kind of nasty. The next thing I know I’m in my boss’s boss’s office having to explain how this guy’s an idiot. Which he is, or was. To put it more kindly, he was from a different universe. I was in a computer science universe, he was in a physics universe. We were solving different problems and he should have minded his own business. Or at least come talk to me before sending a memo to my boss’s boss, so maybe I could save him the embarrassment. There are many places where I go where that memo is on the wall, pinned to some cubicle -- “the old Bachrach memo” -- because it’s just such a great example. Now Bachrach, I ran into him a decade or two after that unfortunate memo, whereupon he was letting it be known that he’d helped invent Ethernet. How he got there I don’t quite know, but it had something to do with this memo being really instrumental in fixing some of the early problems with Ethernet, which is a complete hallucination." http://archive.computerhistory.org/resources/text/Oral_History/Metcalfe_Robert_1/Metcalfe_Robert_1_2.oral_history.2006.7.102657995.pdf http://archive.computerhistory.org/resources/text/Oral_Histo...

himinlomax 7y ago

Note that what we now call Ethernet does not work like this (CSMA/CD) any more, now that we exclusively use switches instead of passive hubs. Wifi does, though.