Saving Ethernet: the birth of switching (or actually Bridge)

An interesting short article from IEEE spectrum on the two guys at DEC responsible for the underpinning tech of "store and forward" and what has ultimately led to we have today as the all dominant LAN (and WAN) switched Ethernet technology standard.

This fork in the road took "old" CSMA/CD Ethernet on coax and spun in into a something which successively conquered and smashed FDDI, Token Ring and ATM - which could all at various points in time legitimately claim technical, throughput and efficiency superiority over Ethernet.

"No one knows what would have happened to Ethernet had Mark not invented the learning bridge. Perhaps someone else would have come up with the idea. But it’s also possible that Ethernet would have slowly withered away."

IEEE Spectrum: How Engineers at Digital Equipment Corp. Saved Ethernet

Token Ring had its problems because of the way the signal passed through all the wiring and devices connected to the ring. An Ethernet switch avoided that problem.

Thanks for that, an enjoyable read. I have fond memories of setting up 10Base5 and 10Base2 ethernet networks, and also a Token Ring network for HP Workstations in a couple of Glasgow colleges in the late 80s and early 90s. Nice to see the Spanning Tree protocol getting a mention too - I used to teach that to students around the same time

In reply to a post by Michael_Chare:

Token Ring had its problems because of the way the signal passed through all the wiring and devices connected to the ring. An Ethernet switch avoided that problem.

Back when I was a bit more hands on with these things we had passive TR concentrators, that used IBM Type 1 cabling - extremely thick shielded twisted pair - VERY IBM-esque thing of course in the 80's and 90's. They used a connector that would "heal" the ring as you disconnected a station from the concentrator.

Later of course there were active TR concentrators, that regenerated the token, and physically used RJ45 connections as it was delivered over 'normal' Category 3 or 5 structured cabling, which supplanted all the Type 1 we'd been paid to install 5 years previously 😂. I have a vague recollection the ones we came across were made by Allied Telesyn, but don't quote me on that.

Good old days eh 😂

In reply to a post by potterer:

Thanks for that, an enjoyable read. I have fond memories of setting up 10Base5 and 10Base2 ethernet networks, and also a Token Ring network for HP Workstations in a couple of Glasgow colleges in the late 80s and early 90s. Nice to see the Spanning Tree protocol getting a mention too - I used to teach that to students around the same time

When we were naughty undergrads, we'd think nothing of causing mass havoc in a computer lab full of VT100' type terminals or Tektronix X-terminals that were cabled up with a mixture of thin and thick ethernet. Amazing how much carnage a lowly missing BNC terminator can do 😅

That was always a good practical demonstration for students who couldn't be convinced that reflections on improperly terminated transmission lines were a real thing - I seem to recall that a similar challenge existed on the earliest SCSI storage systems as well

I used to go to the IBM London South Bank office to listen to lectures by a man from IBM. I later saw him at some other event. I think IBM had dispensed with his services. I think IBM lost out when cheaper Ethernet replaced expensive SNA.

There is quite a good book you should read about how and early networked was hacked and how the perpetrators were found by a physics student who studied stars.

In reply to a post by Michael_Chare:

I think IBM lost out when cheaper Ethernet replaced expensive SNA.

I read IBM sold Token Ring and patents and technology to Cisco, whom of course buried it 🤣

In reply to a post by Michael_Chare:

There is quite a good book you should read about how and early networked was hacked and how the perpetrators were found by a physics student who studied stars.

Is that the Cuckoos Egg? A good read, but I don't think the right one.

I'd say it was TCP/IP that replaced all things SNA.

Can’t imagine they got a lot for it. By the end of the 90s and certainly around the millennium it was toast in general corporate networks. Think the only market left was IBM as I recall using it in their mini and mainframe bits and bobs.

Edited by Pheasant (Wed 18-Dec-24 18:55:31)

Another badass that defined expectations 🙈😂

In reply to a post by Pheasant:

Can’t imagine they got a lot for it. By the end of the 90s and certainly around the millennium it was toast in general corporate networks. Think the only market left was IBM as I recall using it in their mini and mainframe bits and bobs.

True. I came across it in random places, had to get a PCMCIA token ring adaptor for the laptop to go to some clients. Was glad it went!

Hilarious. Around that time I had an IBM T/R PCMCIA card kicking around my ‘kit bag’ for ages. I can’t really remember exactly how I came about it. Might’ve been from someone at the bank where I was working on a project and had my company laptop which I needed to connect.

Ah yes, memories. Token ring, FDDI, ATM, original thick ethernet (always yellow) back in 1981/2, worked on all of those in my time. Cambridge ring too - anyone else remember that? Today's ethernets have little in common with the CSMA/CD original back then. But I will resist, for now anyway, the temptation to go into old man in chimney corner mode.

I think so. I will have a look when I get home at the weekend. I bought the book about 30 years ago.

Did you find the book perchance?

I’ve just picked up Eats, Shoots and Leaves to refresh my grey matter and possibly improve my woeful punctuation 😂

Another take on the history of Ethernet over twisted pair back in the eighties…

TWISTED: The dramatic history of twisted-pair Ethernet.

(am liking this particular YouTube channel)

Thank you for the link to interesting.video. It did not mention token ring which IBM used to promote.

TR wasn’t really the focus of the video, mentioned in passing as a means to get the collective companies variously (in)fighting on the earlier twisted pair Ethernet standards to come together to defeat their mutual bogey-man - aka Token Ring.

I was still actively using TR in the late nineties in Sydney, in a particular certain back offices in Commonwealth Bank where there were still strongholds going back to their vestiges of network control with outsourcing via EDS and historic IBM networking history (aka Type 1 cabling - probably more recognisable today as a the forbear of some shielded Cat 8 nonsense 🤣)

The eventual dominance of Ethernet probably wasn’t clear cut until at least the mid nineties, even then upstarts like ATM and the old FDDI weren’t totally vanquished.

In reply to a post by Pheasant:

The eventual dominance of Ethernet probably wasn’t clear cut until at least the mid nineties, even then upstarts like ATM and the old FDDI weren’t totally vanquished.

Agreed. The cost of 48 port enterprise switches started to fall I think then. Type 1 cabling was in use at IBM Hursley I saw on a training visit in around 1998 with the adaptors to RJ45. Also I think Boots tills were all connected via Type 1 token ring connectors under the desk.

25+ years later you find hardly anyone using wired connections in offices, everything has moved fast to WLAN, only the AP's on the ceiling (or hidden in the ceiling) are using any fixed cabling. Even Dell and HP have copied Apple and removed Ethernet ports on modern laptops.

Boots tills used type 1 cabling but it wasn't token ring originally, it was the store loop technology used by 3680 (and later 4680) POS equipment.

I worked on teller PC replacement programme for Westpac (in Aussie) back in the day - late nineties - and were doing precisely that, moving from IBM terminals to windows NT 3.5 branch server and terminals.

As I recall we did the cutover on two separate nights, the first night was removing the Type 1 and putting in Cat 5e cabling to all the teller positions and running the green screen terminals over custom adapters/baluns on the new structured cabling and commissioning the branch server.

On the return evening visit the teams would then install the the new teller terminals, patch them all up to a new branch switch and cutover everything onto the new Windows based branch terminal system.

Yes, what we now call a network switch was originally a multi-port bridge. Back in the day, before my day, a switch was a layer 1 device which physically switched circuits. But with the advent of packet switching, the term 'switch' took on a new meaning.

At high school our network was thin Ethernet, and a couple of bridges between some of the segments. (We also had repeaters). When I went to university everything was 10base-T, which used the now ubiquitous RJ45 connections.

You might be interested in a video about the first commercial Ethernet bridge, which also has a demo of the device working: https://www.youtube.com/watch?v=Hvqv9QcTcfA.

Edited by andrum99 (Mon 02-Jun-25 12:49:44)

Speaking of OSI layer 1 devices, Ethernet hubs were extremely popular in the early days of 10BaseT. At that point in time they were much cheaper than “proper” Ethernet switches (operating at OSI layer 2).

At some point in time, thinking back, probably from the late nineties and into the early 2000’s the cost advantage of hubs diminished significantly. Probably due to ever decreasing costs of Ethernet chipsets, the massive expansion in network equipment manufacturing and vendors (especially from the far east - read Taiwan and China) and thus good old economies of scale.

Ethernet switching then became dominant (over hubs), not only in medium and large enterprise but also in small offices and homes. The so called SOHO market - basically many folks in this readership.

Edited by Pheasant (Tue 03-Jun-25 06:47:33)

In reply to a post by andrum99:

You might be interested in a video about the first commercial Ethernet bridge, which also has a demo of the device working: https://www.youtube.com/watch?v=Hvqv9QcTcfA.

Yes good video. If you want it from the horses mouth so to speak, read the linked IEEE Spectrum article by Alan Kirby the co-inventor of the subject matter in the video from The Serial Port.

Edited by Pheasant (Tue 03-Jun-25 06:57:33)

In reply to a post by Pheasant:

Ethernet switching then became dominant (over hubs), not only in medium and large enterprise but also in small offices and homes. The so called SOHO market - basically many folks in this readership.

Just how I remembered it. Switching was quite rare when the UK started going with domestic broadband (NTL’s cable modem trial in summer 1999) and it wasn’t until 2000 that the first home router was being sold in the states (Linksys BEFSR41) with 4 LAN and 1 WAN, and that was a hub….

Ethernet being automatically part of all desktops / laptops happened during the 2000s, USB appeared faster and then PCMCIA/PC Card slots disappeared as built in Ethernet and USB could do it all for cheaper and more reliable.