All posts tagged wiring

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  Connections to the cable were originally made with a “tap”, requiring physical piercing of the cable to reach the center conductor.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.

My readership is limited, so consider a post to be “viral” if I get more than 2 thumbs up at the bottom of a page.  (Incidentally, I’ve only ever gotten one thumbs down, for this post, but I don’t know why.)  My 2021 post For the Love of Wiring got 3 thumbs up (!) but actually did get a lot more hits than usual after Tom Hollingsworth linked to it from his own blog.  How about a little more layer 1?

After my initial foray into stringing Cat 3 cable around in various unwise ways, Category 5 quickly became the standard.  I hated Cat 5 cable.  Cat 3 had a small number of twists per foot (or meter, non-Americans, or metre, Brits!), so upon removing the jacketing of the cable it was quite easy to untwist it before punching it down.  Cat 5 is very twisted.  Not only are the pairs hard to untwist, but they remain kinked after untwisting, and they take a lot of work to smooth out.  (If you correctly terminate Cat 5, you shouldn’t have to untwist and smooth the wires, but I didn’t know that at first.)  I remember once, on my 10 Mbps Ethernet, running a speed test on Cat 3 cable and then being very disappointed when I saw no improvement running the same test over Cat 5.  (Doesn’t quite work that way, and for 10 Mbps, Cat 3 was more than adequate.)

I did a lot of research to learn how to run cable the correct way.  Mainly this means preserving the tight twists.  Cat 5 cable cannot be kinked or bent sharply, and the twists must be maintained up to the point of termination.  Not only did I use this information to run my own cable, but once I took a job at a computer consulting company, I oversaw many cabling projects and needed to inspect the work done by our vendors.  Voice cable did not have the stringent requirements of data, so often phone cabling experts would run the Cat 5 with tight bends and would untwist the wires several inches before punching down.

The consulting company used one such phone installer to do many of their jobs, often as a sub-contractor.  This was in the days before wireless, when every computer connected to the network, even laptops, had to be plugged in.  I remember one client, a small architectural firm in Berkley, where our installer ran a brand new, Cat 5 Ethernet network.  We showed up, installed a hub, Ethernet cards, etc., and got everyone online.

A week or so later we got called back.  Stations were dropping on and off the network.  I fought may way through Bay Area traffic back to the office to figure out what was going on.

With any layer 1 issue, replacing cables is a good first step.  As I unplugged one station from the wall jack, the entire jack and face plate fell off the wall.  Whoops.

Normally when a network jack is installed in an office building with sheetrock (drywall) walls, the installer cuts a fairly large opening in the sheetrock and then installs a “low voltage ring”.  This ring secures to the drywall from behind, and provides a place for the faceplate to screw into.  Then the Cat 5 cable is punched down on a small “keystone” jack, over which a cover is placed, and which then snaps into the faceplate.

Low voltage ring

Our clueless installer had not done this.  Instead he cut a hole in the drywall just small enough for the jack to fit through.  He never installed the low voltage ring, instead screwing the faceplate directly into the drywall.  He also never installed the cover on the contacts on the jack, so the contacts were covered with drywall powder.  Because screws don’t hold well in drywall, when I pulled the cable from the jack, the whole thing fell out.  I also found out that when he had installed the small office patch panel in their supply closet, he put the screws straight into the drywall as well.  Normally you would use a backboard, screw it into a stud, or at least use drywall anchors.  The patch panel fell off the wall too.

Keystone jack with cover

Needless to say, I wasn’t too happy and neither was the customer.  I hate taking the fall for something that’s not my fault, but the customer considered it our mistake.  I made the cabling vendor come out and redo the entire installation.  After that, I told the owner of our firm to never use that vendor again.

A major concern, even with good cabling vendors, was having people in the office around the cables before they were fully installed.  I remember one client where we had a reputable vendor install the cabling before everyone moved in.  They ran one really large bundle of Cat 5 on the floor, because the client was going to install a raised floor afterwards.  Unfortunately, it took them months to get the raised floor in, and the bundle of cable ran right outside of a row of offices.  People stepped on them going in and out of their offices.  One time I remember a guy in cowboy boots standing right on top of the bundle.  I asked him to move.  By the time the floor covered the cables, they had gone from a clean, round bundle, to totally flattened.  Oddly enough, I never had any problems with the wiring in the time I worked there.

When I worked at the San Francisco Chronicle, our cabling vendor was installing some new fiber optic cabling to some data center racks.  The data center also housed our operations team (NOC, more or less.)  There was one lady who worked there who was very nice, rather large, and a tad immature.  The vendor had laid the fiber out on the floor before routing it under the floor tiles.  We looked up and there was the woman, jumping up and down on the fiber and laughing hysterically.  “Is this good for the cables, is this good for the cables?!” she was saying.  When we explained the interior was made out of glass, she looked horrified and stopped, but it was too late.  It cost us a bit, but fortunately for the NOC lady, she was in a union and well protected.

Working on software now, I don’t have to worry about cabling very much anymore.  I touch racks so infrequently I still call SFPs “GBICs”.  I do think it’s good for network engineers to stay informed on layer 1.  As much as you may know about protocols, software defined networking, or automation systems, none of it will work if the wires aren’t right.


We’ve moved into a wireless world, which is too bad for me because I love, more than anything, wiring.  I miss the days of good old Cat 3 cable, T1 lines, and ISDN BRIs.  I miss 66 blocks, punch down tools, cross-connect wire, and tone/probe kits.  And butt sets.  Especially butt sets.  Now I just have to add random wall receptacles around my house since, thank goodness, 120 volts cannot be delivered wirelessly.  But phone and network wiring was much more fun.

I first got interested in wiring when I was working at a small museum exhibit design and fabrication company in Marin, California.  One day, I had to have a new phone line installed, and I called in Pacific Bell to do the work.  Under the receptionist’s desk was a wall plate with two RJ-11 jacks, already in use.  “There aren’t any free jacks,” I told the phone guy.

“It doesn’t matter, as long as there is enough wire,” was his cryptic response.  I let him do his work, and when he was done I saw a little surface-mount RJ11 jack on the wall.  It had two blue and yellow wires running from it, going underneath the existing faceplate and somehow into the wall.  How on earth did he do that?  I remember thinking.

I waited until everyone went home.  I unscrewed the faceplate and found that the blue/yellow wire pair was spliced to the brown pair of wires in the cable that serviced the existing jacks.  The splice was a 3M UR-type, which looked like a piece of candy.  I was captivated.  How did he know where the brown wires went?  Where did the incoming phone line enter the building?  How did he connect them up?

The fun thing about the days before ubiquitous Internet was that you couldn’t get answers immediately.  When I found the 66-type punchdown blocks that formed our little MDF, I couldn’t Google the part number to figure out what they were.  Google didn’t exist.  I had no idea how to terminate a wire on one of them.  While thumbing through a Jensen Tools catalog our purchasing agent had I got an idea of how it worked.  There, I saw listed a “66 punch-down tool” and I had noticed the numbers “66” on the block.  OK, so they go together and the wire gets in the clip by “punching down.”

I didn’t have the money to afford a punch-down tool.  So I got a pair of pliers and a pair of forceps and started doing terminations myself, guiding the wire into the clip.  Sure, sparks were flying, but phone systems are robust, aren’t they?

It turns out not as robust as you might think.  Back in the day, phone lines provided by the phone company (POTS service) were indeed robust and could handle quite a bit of sparking and shorting.  But the Nitsuko (emphasis on the “suk”) system we used did not take kindly to my laissez-faire approach to wiring.  One day, while doing a move, I shorted out a couple terminals and all the phones in the building went out.  I came out of the closet with pliers in hand and everyone knew what happened.  This being before cell phones, business was done for the day.  Luckily we got our phone company out to replace the bad part, and they did it under warranty.  It was at this point I invested in a proper punch-down tool and learned how to wire correctly.

The author’s tools: Butt set, punch down tools, tone/probe set, and connectors

I saved up a lot of money and eventually got a test set, otherwise known as a “butt set”.  The butt set looks like an oversized telephone handset, and is the official sign of a telco wiring guy.  It also was my passport into telephone wiring closets–when a security guard sees you have a butt set, they just assume you’re a real phone guy.

I practiced my technique in my father’s 1910-era house.  The decades brought with them layers of phone wiring, including two 50-pair feeder cables and a 66-style punch-down block.  Why and how the feeder cables ended up in a house with 3 phone lines is a mystery to this day.  But I used the 66-block for practice and dissected the criss-crossing wires in his house, tracing them out with my trusty tone/probe set.

Wiring skills came in handy many times in my career as a network engineer.  I remember one customer I had in the late nineties who had ordered 8 Centrex lines from Pacific Bell.  The technician showed up to do the cross-connects, but he was not the sharpest knife in the drawer, did two of them, and left.  Using my butt set passport, I got access to the MDF, figured out the right punch-down block that fed to the customer’s suite, and ran the cross-connects myself.

When I worked for the San Francisco Chronicle, we actually had an in-house wiring tech.  Her name was Mona Lesa.  She couldn’t care less if I did my own wiring, as long as I adhered to her standards.  One day I had a frame relay T1 installed in our Sacramento bureau office, and once again, Pac Bell forgot to connect it to the suite.  The bureau was located in the Old Senator Office Building across from the state capitol.  I got the security guard to let me in to the MDF in the bowels of this historic building.  I figured out that one of the interconnects was in the office of a lobbying firm, and the receptionist dutifully let me in to do the wiring.  With my butt set I could clip into any of their phone lines and listen to their conversations without them knowing.  I didn’t but I was amazed that I could go anywhere to do cross-connects.

On another occasion, a customer of mine had two phone lines installed and had a weird problem.  If she picked up one line and dialed the other, she’d hear both ringing and a busy signal at the same time.  I found where the Pacific Bell guy had done the cross-connect, and realized he mixed the tip and ring wires for the two phone lines.  A couple punches and all fixed.

Phone wiring was always the perfect blend of mind and body to me.  To do it you need to work with your hands, but you also need to use your mind.  Some wiring closets were rats nests of 24-gauge wires color-coded with more colors than a tie-died shirt.  Finding that one pair you needed, and marrying it up to the other end was always a nice diversion from staring at a screen.

Alas, my tools mostly sit unused.  Regular POTS lines rarely exist now, and even they aren’t delivered on single copper pairs from the CO switch.  PBXs and key systems have gone the way of the dinosaur, replaced by voice-over-IP and now by cellular phones.  Nobody wants to be tied to wires anymore, and yet by un-encumbering ourselves in the name of freedom, we’ve paradoxically lost our freedom.  When you don’t need to be physically tied to a location for connectivity, you can never escape connectivity.  And that’s not entirely a good thing.