5 ms·

I worked at Novell in the late 80s, early 90s. In the LAN world, IPX/SPX worked pretty well but it was certainly steamrolled by TCP/IP. Since I started out in

I worked at Novell in the late 80s, early 90s. In the LAN world, IPX/SPX worked pretty well but it was certainly steamrolled by TCP/IP. Since I started out in the testing department, I not only had to deal with a bunch of protocols (IPX, NetBios, etc.) but I also had to deal with a bunch of stuff at the physical layer. Instead of everything being Ethernet, we had Token-ring and ArcNet cables running everywhere.

zwieback 4y ago
Yup, I worked on a PC-to-Mac networking server product and we tested with TokenRing as well. Massive hardware but good performance. We also had a lot of coax wire in those days. To this day I still look down on twisted pair and the garbage Ethernet connectors we use now.
- anyfoo 4y ago
  Electrically, there's not much reason to look down on Twisted Pair. It is an ingenuous way to achieve what coax does as an unbalanced transmission line with, well, a twisted pair of wires that form a balanced (differential) transmission line. You might need to add some shielding in some situations, but that's just a piece of foil. Most importantly, the two wires that make up the pair really just are common single-ended wires, not elaborate coax or anything else. A single coax transmission line supporting 10Gbps Ethernet would likely be much more expensive than the little bundle of twisted pairs we typically use nowadays. In many ways, for its applications, twisted pair and RJ45 connections are better than coax wiring with BNC.
  - cesarb 4y ago
    > Electrically, there's not much reason to look down on Twisted Pair. Yeah, but mechanically, the RJ45 plug with its finicky easily breakable plastic tab can be an annoyance. And it's easy to see that the pin ordering is not ideal, with the pair in the middle splitting another pair. AFAIK, there exists a more robust connector (the M12 connector), but it doesn't seem to be that common.
    - anyfoo 4y ago
      True, the plastic tab can be annoying, but I guess the sheer abundance of patch cables nowadays means the cheapness of the connector, while retaining pretty good ease of use (better than many others), makes up for that drawback. Maybe something slightly more resilient could have been designed within the same parameters, had people known just how ubiquitous that connector would become. Maybe M12 is that, but it looks way more expensive at first glance. Possibly more laborious to connect/disconnect, too, with its screw-locking? Seems to be better for applications where a secured connection is more important (transportation is mentioned). And yeah, the 1000base-T pin ordering seems unusual. I'm curious about the history there, because even 10base-T (where I thought Ethernet for Twisted Pair begun) had this really weird pinout, which does not support my initial theory that it was because Ethernet kept progressively adding more differential pairs: https://www.arcelect.com/10baset.htm https://www.arcelect.com/10baset.htm It may well be because they added the original two pairs to a pinout that already carried something else, but the diagrams don't say what those other lines were for, so if anyone knows... According to those same diagrams, though, it seems to be more common to split up the pairs than not, which now makes me wonder if there is any benefit to that?
      - tmm 4y ago
        > but the diagrams don't say what those other lines were for, so if anyone knows... Telephones. Telephones are why. Those other two pairs were often used for voice communication. If you had four-pair station cabling, the pairs were provisioned on the modular jack from the inside out. So line one was the blue/blue-white pair on the inner pins, line two was the orange/orange-white pair on the next two pins, and so on. Ethernet comes along and lots of places where you'd want a network connection already had a phone jack with two pairs unused, so for signal integrity reasons those are moved to the outside and used for data, leaving the inner two pairs where they were to be used for voice. But why 4 pairs in the first place? Just about the time that Ethernet was transitioning from coax to twisted pair, the digital PBX was taking over from key systems (1A2) and reduced the number of wires required for a business telephone from 25 pairs (or more ... secretarial sets often had 100 or more pairs) per station down to 4 (for HORIZON[0]) and later two pairs (DIMENSION and eventually Merlin, Definity, etc.). So if you're wiring a new building, you can just run one CAT-3[1] cable to each desk and use the first two pairs for voice and the second two for data[2]. [0] OK, for the pedants out there, HORIZON wasn't ever very popular and really pre-dated Ethernet, but the telecom world moves kinda slow [1] Wasn't really CAT-3 until the early 90s [2] Not on the same jack, but by using pins 1, 2, 7, and 8 for data, you can plug the wrong cable in without risk of hurting the phone or your computer's network card
  - jbverschoor 4y ago
    In the 90s, coax was way cheaper than utp.

zwieback 4y ago

Yup, I worked on a PC-to-Mac networking server product and we tested with TokenRing as well. Massive hardware but good performance. We also had a lot of coax wire in those days. To this day I still look down on twisted pair and the garbage Ethernet connectors we use now.

anyfoo 4y ago
Electrically, there's not much reason to look down on Twisted Pair. It is an ingenuous way to achieve what coax does as an unbalanced transmission line with, well, a twisted pair of wires that form a balanced (differential) transmission line. You might need to add some shielding in some situations, but that's just a piece of foil. Most importantly, the two wires that make up the pair really just are common single-ended wires, not elaborate coax or anything else. A single coax transmission line supporting 10Gbps Ethernet would likely be much more expensive than the little bundle of twisted pairs we typically use nowadays. In many ways, for its applications, twisted pair and RJ45 connections are better than coax wiring with BNC.
- cesarb 4y ago
  > Electrically, there's not much reason to look down on Twisted Pair. Yeah, but mechanically, the RJ45 plug with its finicky easily breakable plastic tab can be an annoyance. And it's easy to see that the pin ordering is not ideal, with the pair in the middle splitting another pair. AFAIK, there exists a more robust connector (the M12 connector), but it doesn't seem to be that common.
  - anyfoo 4y ago
    True, the plastic tab can be annoying, but I guess the sheer abundance of patch cables nowadays means the cheapness of the connector, while retaining pretty good ease of use (better than many others), makes up for that drawback. Maybe something slightly more resilient could have been designed within the same parameters, had people known just how ubiquitous that connector would become. Maybe M12 is that, but it looks way more expensive at first glance. Possibly more laborious to connect/disconnect, too, with its screw-locking? Seems to be better for applications where a secured connection is more important (transportation is mentioned). And yeah, the 1000base-T pin ordering seems unusual. I'm curious about the history there, because even 10base-T (where I thought Ethernet for Twisted Pair begun) had this really weird pinout, which does not support my initial theory that it was because Ethernet kept progressively adding more differential pairs: https://www.arcelect.com/10baset.htm https://www.arcelect.com/10baset.htm It may well be because they added the original two pairs to a pinout that already carried something else, but the diagrams don't say what those other lines were for, so if anyone knows... According to those same diagrams, though, it seems to be more common to split up the pairs than not, which now makes me wonder if there is any benefit to that?
    - tmm 4y ago
      > but the diagrams don't say what those other lines were for, so if anyone knows... Telephones. Telephones are why. Those other two pairs were often used for voice communication. If you had four-pair station cabling, the pairs were provisioned on the modular jack from the inside out. So line one was the blue/blue-white pair on the inner pins, line two was the orange/orange-white pair on the next two pins, and so on. Ethernet comes along and lots of places where you'd want a network connection already had a phone jack with two pairs unused, so for signal integrity reasons those are moved to the outside and used for data, leaving the inner two pairs where they were to be used for voice. But why 4 pairs in the first place? Just about the time that Ethernet was transitioning from coax to twisted pair, the digital PBX was taking over from key systems (1A2) and reduced the number of wires required for a business telephone from 25 pairs (or more ... secretarial sets often had 100 or more pairs) per station down to 4 (for HORIZON[0]) and later two pairs (DIMENSION and eventually Merlin, Definity, etc.). So if you're wiring a new building, you can just run one CAT-3[1] cable to each desk and use the first two pairs for voice and the second two for data[2]. [0] OK, for the pedants out there, HORIZON wasn't ever very popular and really pre-dated Ethernet, but the telecom world moves kinda slow [1] Wasn't really CAT-3 until the early 90s [2] Not on the same jack, but by using pins 1, 2, 7, and 8 for data, you can plug the wrong cable in without risk of hurting the phone or your computer's network card
- jbverschoor 4y ago
  In the 90s, coax was way cheaper than utp.