ethernet

All posts tagged ethernet

Ivan’s recent very interesting post on LAN Data Link addressing takes me back.  Specifically, footnote #1, referring to “ThickNet” Ethernet:  “The coaxial cable had to be bright yellow”.  In the US, at least, we also used to call the stuff “Frozen Yellow Garden Hose”, for obvious reasons.

The original Ethernet physical medium was rather interesting.  I’ve often talked about my love of layer 1, but I got into the business in the twisted-pair era.  I did do a bit of ThinNet networking, but only a little.  And I had one encounter with ThickNet.  Twisted pair is fun to work with and easy to manage.  Coax is not.

The original “ThickNet” Ethernet used, as the name implied, a fairly thick coaxial cable.  The cable had to be physically routed in a path which put it in proximity to the stations that would use it.  Connections to the cable were originally made with a “tap”, requiring physical piercing of the cable to reach the center conductor.  A drop cable then extended down from the tap to the station using it.  Messy, and inconvenient.

“ThinNet” used a substantially smaller cable, and it was far more flexible.  Think about something close to your TV cable coax, but even more flexible, and using BNC connectors.  As with ThickNet, the routing of the cable was tricky, but instead of physical taps we used T-style connectors to add stations into the network.  My very first Ethernet network consisted of a ThinNet segment tied into a 10Base-T twisted pair segment with an adapter.

I’ve written a few times about my first full-time networking job at the San Francisco Chronicle.  Back when I worked there, people actually read the paper and its printing and distribution was a big deal.  After the 9/11 attacks, you may remember several authorities and news agencies in the United States were mailed powdered anthrax.  These events prompted our management to set up a “disaster recovery” site, where we would have enough equipment to produce the newspaper in the event our main building was incapacitated.

For a reason I never understood, they chose a building on the same block.  Behind the Chronicle building were a number of alleys, and the company owned a building back there.  It made no sense at all.  If an earthquake hit, and the main building was destroyed, presumably the building across the street would be too.  If anthrax were mailed to the main building, I assume the entire block would be shut down.  But anyways…

We set up this empty building with computers and phones, and added a frame relay connection so it could connect to the WAN if the main building were out.  But we still wanted a high speed connection for file transfers and backups, so I was tasked with somehow getting a faster connection to the HQ.  I called our cabling contractor, who also resold several wireless building-to-building alternatives, but they were all expensive.  Then I made a discovery.

In the basement of this historic building was our MDF, the main phone equipment and wiring room.  There was a large distribution frame for phone wiring to the entire building, three or four racks of phone equipment, a desk that looked like it was made by prisoners, and a grumpy phone lady who sat in there.  One day I also noticed a pipe with a tag hanging off of it.  It had the address of the disaster recovery building in it, and a disconnected piece of frozen yellow garden hose hanging down.  Could it be?

I went outside and saw a conduit running from the top of the HQ building to the disaster recovery site.  At this time, ThickNet was not being used by anyone, but 10Mbps would be more than sufficient for this DR site that would probably never be fully staffed.

One of my fellow engineers (who had worked at the paper forever) had a lab packed full of all kinds of esoteric electronic equipment.  I went spelunking in the dingy room and found two ThickNet transceivers.  Thankfully the ThickNet was terminated on both ends with connectors, so I didn’t need to drill and tap.  I hooked up the transceivers, connected the RJ45 ports to a nearby switch on each end, and then tested the connection.  It worked!  I had no idea how many years that frozen yellow hose had been in place, but it took one problem off my plate pretty easily.

The “DR” building sat unused for several years, but with keys to the building it made a nice place to take a nap occasionally.  The site was decommissioned eventually.  I wouldn’t be surprised if the frozen yellow garden hose is still in the conduit to this day.

A lot more detail on ThickNet can be found at Matt’s Tech Pages here.

I’ve mentioned in the past how my first job in IT (starting in 1995) was as a “systems administrator” for a small company in Marin County, California.  The company designed and built museum exhibits, and its team of around 60 employees was split between fabricators, who built the exhibits, and office workers.  Some of the office workers did administrative work, while others were designers.  So, I was managing a network of around 30 computers, all Macs.

When I got to the company, the computers were networked using LocalTalk, a LAN technology from Apple, and specifically the PhoneNet variation.  PhoneNet was a product from Farallon Networks which enabled you to send the LocalTalk signal down a single pair of ordinary telephone wire.  The common practice was to use an extra pair of phone wires in the same cable that carried the user’s phone line.  In my first Netstalgia piece, I mentioned that my PhoneNet network was entirely passive, and ran into a lot of challenges as a result.

PhoneNet was also slow, and our designers had to transfer large files.  I decided to set up a separate Ethernet network for them.  All I knew about Ethernet was that it was faster, and that the higher-end PowerPC’s used by the designers supported it.  These computers had an AAUI port, a modification of the AUI port commonly in use for Ethernet connectivity at the time.  An AUI port required a transceiver to connect it to the Ethernet network.  Why?  Because we had Thicknet and Thinnet coaxial Ethernet, 10Base-T twisted pair and fiber optic Ethernet as well.  The universal AUI port (and Apple’s AAUI equivalent) gave you a choice of medium.

I didn’t really know how to make this work, and Google was not available at the time.  I had heard that you needed a “hub”, but I wasn’t sure exactly why or what the hub did.  The MacWarehouse catalogs I used to receive at the time advertised a product called an Etherwave, from the same company that made the PhoneNet transceiver.  The Etherwave allowed daisy-chaining of a twisted-pair Ethernet network.  I don’t know why, but this seemed easier and cheaper to me that buying a hub.  It was neither.

Farallon Etherwave Adapter

I bought a bunch of Etherwave adapters, got a ladder, and spend a night running Cat 3 cable in the suspended ceiling, and crimping RJ45 cubes.  Finally, I daisy chained everything together, and switched the computers to the new Ethernet network.  It worked very well–file transfers were screaming!

The designers loved it, but there was a flaw.  The Ethernet network was not connected at all to the LocalTalk network.  The LocalTalk network was where email, printing, and many other services resided.  Their computers had connections to both, but they had to go to a control panel and switch between one or the other.  That meant, if they wanted to do a file transfer, the two designers would have to shout to each other to switch networks, at which point they could do it peer-to-peer.

There was another problem.  Apple’s networking software, called OpenTransport, was notoriously buggy.  The switches between Ethernet and LocalTalk resulted in frequent crashes and reboots.  The initial thrill was wearing off.

I searched through catalogs and primitive websites looking for a solution.  I learned that I could buy a device called a router to connect the Ethernet and LocalTalk into a single unified network.  I desperately looked for the cheapest one.  My go-to vendor, Farallon, made a router but it was way too expensive.  Finally, I found a cheap router called a PathFinder manufactured by Dayna systems.

I went to my boss, the VP of operations.  I showed her the price (maybe $800?) and she balked.  This company ran a tight ship, and she said we couldn’t afford it.

I went back to our head designer and asked her to keep a post-in on her computer for a day, with a tally mark each time she had to reboot due to the Ethernet to LocalTalk switching.  Then we timed how long it took her to reboot.  I went back to my boss and showed her how much time was being lost each day to a single designer.  Her left hand flew over her the buttons on the calculator on her desk, then she looked up at me.  “Buy the router,” she said.

The PathFinder did indeed fix the problem.  And so my first Ethernet network, as well as my first experience configuring a router, came at a company in 1995 with 30 Macs, and I’ve spent decades working with both technologies since those days.