[SAI_Peregrinus]

It's interesting how long twisted-pair cabling has stuck around, to the point that it's associated as being the physical medium for Ethernet. Ethernet started with coaxial cables, but soon lost its association with those as twisted-pair was cheaper & easier to work with. And it's stayed that way for so long that a CAT-5 cable with RJ-45 (really RJ-38 but that's excessively pedantic) connectors is an "Ethernet cable", and a perfectly usable fiber optic cable is something else!

[wolrah]

> (really RJ-38 but that's excessively pedantic)

RJ-38 is a 8P4C (eight pin, four conductor) modular connector with shorting bars used to allow an alarm system or similar to seize a phone line when plugged in but for the line to still operate normally with the plug removed.

You might be thinking of RJ-48 which is used in T1 service and thus often has "RJ45" cables plugged in to it, but technically that's 8P4C as well, also with (differently configured) shorting bars that will physically loop the T1 if disconnected.

Ethernet uses an 8P8C modular connector but it's not any of the Registered Jack standards

[recursive]

I've been in software for decades, and it was only right now that I realized that what I'm calling "ethernet cable" is maybe something else. Not that I understand the finer details of what you're saying.

[Symbiote]

You can find them all described here: https://en.wikipedia.org/wiki/Ethernet

Specifically these:

- https://en.wikipedia.org/wiki/10BASE5 (early 1980s)

- https://en.wikipedia.org/wiki/10BASE2 (mid 1980s, cheap installations like my high school in the early 1990s).

[mbreese]

It is an Ethernet cable. It’s just not the only kind of Ethernet cable.

[LukeShu]

> RJ-45 (really RJ-38 but that's excessively pedantic) connectors

If we're being overly pedantic:

- the RJ numbers refer to not just the connector but the pinout and such

- the RJ (registered jack) numbers refer to just the "jack" side, not the "plug" side

So even though an "Ethernet" cable has plugs on it that fit into an RJ38X jack, its wrong as well to call it an RJ38 plug:

- different pinout

- the plug is the mechanically the same, but pedantically it isn't correct to call any plug a registered jack, because it's a plug not a jack

- the jack is mechanically different; an RJ38X jack shorts pin 1 to pin 4 and pin 5 to pin 8 when there's not a cable plugged in to it (this makes it a "series jack" instead of a regular "jack").

                        Name  | Mechanical jack                  | Mechanical plug
    47 CFR part 68 (registered jacks)
                        RJ45S | miniature 8-position keyed jack  | miniature 8-position keyed plug
                        RJ38X | miniature 8-position series jack | miniature 8-position plug
    ANSI/TIA-568 (Ethernet)
                        T568A | miniature 8-position jack        | miniature 8-position plug
                        T568B | miniature 8-position jack        | miniature 8-position plug

I don't believe any registered jack uses a miniature 8-position unkeyed jack (but scanning through 150 pages is a pain and for some reason Ctrl-F isn't working reliably in this PDF).

(ANSI/TIA/IEC calls them "modular" jacks/plugs, while the FCC calls them "miniature" jacks/plugs, but same thing. Well, same thing the way that CAT-5 and CAT-5e are the same; same, but with different specified tolerances. And just saying "Ethernet" or "568" isn't specific enough here; CAT-6 requires an IEC 60603-7-4 connector, while CAT-5e only requires an IEC 60603-7-2 connector; even though most people would call those the same, they have different tolerances. I don't care to compare the FCC's 47 CFR part 68 requirements with the IEC 60603-7-{2,4} requirements.)