Ethernet Cable Categories Explained: A Brief History…

Dry subject . Though this is quite a good potted history from the blog of Fluke Networks…

https://www.flukenetworks.com/blog/cabling-chronicle...

The first version, 10BASE5

Ah, thick Ethernet and vampire taps... happy days (?)

…or how to take down the entire network with one BNC disconnection 🤣

In reply to a post by Pheasant:

…or how to take down the entire network with one BNC disconnection 🤣

You seem to be enjoying this dry subject a little too much, I could always resurrect the 'Fibre dropwire construction' thread if you want 🤣

🤣🤣

In reply to a post by Pheasant:

…or how to take down the entire network with one BNC disconnection 🤣

Don't remind me, had to super glue the terminating resistors on to the end of the T-pieces to stop the sodding children stealing them once they knew what they did....

Apologies for ripping open those (non-self healing...just like 10Base5/2) scars...😆😂

I was an undergrad in computer science, early nineties, when we discovered how to down a lab full of monochrome NCD X terminals. At least it helped me with my EE understanding the 'practical' application of signal reflections in waveguides

Edited by Pheasant (Thu 24-Mar-22 20:45:38)

All these years later some things haven't changed that much.

People (adults) seeing an ethernet patch lead loose on the desk think "oh that should be plugged back into a data point yes?"
Naturally, they will helpfully do this even when the other end is already patched or comes out of the back of the SIP phone (the PC data passthrough).

At least the managed switches can guard against the resulting loop though it can end up with the phone being disconnected too.

During my seagoing career, 1977-2002, I remember on one ship, with my colleague officers, watching the 1997 film Speed 2 where the villain hijacks a cruise ship by tapping into the ship's network. We all howled with laughter, but in 1999 I was onboard the mv APL France, a Korean built 86,692 Gross Tonnage Containership. I was the only British Officer; all other Officers were Dutch and the crew Indonesian. The Dutch system, at least then, was that their Officers were Maritime Officers, skilled in both Deck and Engineering, whereas the British system was to have Deck Officers and Engineer Officers. I originally was a Radio Officer, but post GMDSS and having electronic and electrical qualifications, became a Technical Officer. We were appointed to ships for around ten weeks as trouble shooters for any tasks which had built up. After our ten week stint, another TO would not return for a year.

One Friday afternoon all was quiet with the promise of a quiet weekend, when everything in the ships control room died, no displays of control and monitoring systems, nothing at all except for self contained instrumentation. The common link was the 10Base2 network. There was very little in the way of technical documentation on this particular ship (and for that matter its sister ship the APL Indonesia which I was on the following year). The Chief Engineer remarked that one end of the network was at his office pc, next to his cabin below the bridge; as for the other end of the network.....

I went to his office and since it was all I could do, I used my test meter to check for the engine room end 50 ohm terminator; my meter read high ohms, so looked like the network coax had gone open circuit, but where?

I went back to the ship's control room to hear that an Officer's wife, who was travelling with her husband, has telephoned him to say that she was dusting his desk in their cabin and had inadvertently parted a cable that was on his desk! When the ships were built, the shipyard had looped the network coax through three Officers cabins which they assumed would be occupied by Engineers (ie a conventional manning system), however the ship owners did not go to the expense of fitting these pc's and simply linked the two BNC coax connectors together. I went to their cabin and found that his wife had managed to pull one of the coax cables out of the BNC plug. I remade the connection and the network and instrumentation returned to normal.

A simple fault, a simple fix, but could easily have been much more difficult to locate.

On another ship found that due to a failing fridge in the Chief Engineer's cabin, there were earth currents flowing through the network coax braid. His fridge got unplugged, but not for long.

Cheers!

Thanks Clive. Great story. 👍

Although 10 Base2 was “elegant” in that it required a minimal cable and no central switch or hub to make it work, it was notorious for being easy to break and a nightmare to fault find. Don’t think any more explanation is needed as to why we graduated to star wired twisted pair!