I was looking up the wiring diagrams for Ethernet cables and found TIA/EIA 568A and TIA/EIA 568B wiring diagrams. They seem to be wired the same, but for the colors used. They swap green and orange. At first I thought I was looking at a crossover cable, but no, they clearly say they should be connected the same at each end. One uses orange and green pairs, while the other uses green and orange pairs for half the signals.
This reminds me of the Star Trek episode where the Black/White guy was fighting the White/Black guy.
Anyone know what's going on with TIA/EIA 568 A vs. B?
All 'normal' patch cables are 568B, so that's the only spec I'd ever want to use.
568A on one end, and 568B on the other end, swaps send/receive pairs so you could connect two hosts (but usually it's a mess if you connect that cable host-to-hub with the old 10baseT or 100baseT units). 1000baseT is smart enough to work with a variety of different pair swaps; POE, I'm not sure of.
The early (10baseT and 100baseT and AUI and even AAUI) twisted-pair interfaces were send-pair/receive-pair wired, and only a 'crossover' cable allowed connecting hosts together. Every hub or switch performed the crossover function internally, sometimes with a 'special' switch or connector for connecting to another hub/switch.
I'm not clear on your preference of B over A. There's no electrical difference between A and B. It's just the color of the insulation inside the cable. Who cares???
BTW, what's the difference between a "patch" cable and other Ethernet cables (not talking about crossover). Cablestogo indicates some cables are "patch" cables with other options not being related, such as "snagless", "slim", "unbooted", "unshielded". These other features are orthogonal to "patch" cables as far as I can tell. What's different about a not "patch" cable?
BTW, using 568A on one end and 568B on the other end, only swaps two pair of wires. The blue and the brown are still straight through. Are they not used in CAT5e?
CAT5e is just a performance spec. The number of wires used depends on the connection speed. 10 and 100Mbit/s use two pairs. 1, 2.5, 5 and 10Gbit/s use all four pairs. Speeds above 2.5Gbit/s need better cable than CAT5e. Better generally means that the pairs are either individually shielded with metallised foil or are separated with a cross-shaped plastic spacer to reduce crosstalk. High-frequency attenuation is also better on the higher-numbered types which typically use slightly thicker wire. Any of the varieties may also have an overall shield.
568B does seem to be the most widely used colour standard. A and B are NEVER intended to be mixed on a single cable. I think the difference may have come about in an attempt to make the colours compatible with certain standards for telephone wiring in buildings which vary in different parts of the world. Patch cables use stranded wire and are intended to be moved repeatedly without damage. Non patch cables are single strand and are used for fixed infrastructure. RJ45 crimp-on connectors are usually only suitable for stranded wire, but there are some that can be used on both types.
Thanks. The stranded vs. solid makes sense. So I should definitely use the stranded patch cables.
It's funny that some people talk about the A vs. B thing as if there's some electrical difference. Such as claiming "this one works, so I'm sticking with it!"
I check my wiring by remembering orange-white/orange/green-white/blue/blue-white/green/brown-white/brown. You can see these colors through the (clear) connector housing on the non-latch side. It'd be confusing (and horrifying, because it recalls the bad old days of CROSSOVER CABLE MADNESS) to see 568A.
In-wall Ethernet wiring is solid wire, and patch cables are stranded wire. Stranded is more flexible, but harder to get the plugs onto (the plugs use a 'corset' to hold the wires, and it has to be inserted into the connector shell without any wires coming loose before crimping. Mostly, people buy solid wire in bulk for installation and field-termination (punchdown insulation displacement in sockets) but buy mass-produced patch cables, in various colors, to plug in the flexible last-few-feet wire.
Some folk use the solid wire for patch cables; I'd not recommend it.
They are used, all right; the blue pair can be used for a voice telephone, OR the blue and brown are used for a second Ethernet (there are splitters available) if you have 10baseT or 100baseT only. Some (presumably older, now out-of-fashion) POE wiring uses the blue and brown pairs for power only. The use of all four pairs for a single network connection came with 1000baseT, which includes a good sense-the-connections algorithm that can even unsnarl (some) bad wiring. On earlier Ethernet variants, those pairs are just spares.
I meant that the copper conductors are normally slightly thicker. CAT6 and 6A seem to use 23AWG whereas CAT5e often uses 24AWG. I agree that the overall cable diameter is much greater, especially for those variants with the cross-shaped spacer which is a real pain. My own preference is to use either CAT5e or if higher performance is needed a CAT6A variant with shielding on each pair but no cross-shaped spacer or overall shield. That gives the minimum stiffness while getting good performance for 10Gbit/s ethernet.
The thing to avoid at all costs is copper clad aluminium which has higher dc resistance which is bad for PoE, can corrode much faster in humid environments and is more likely to break when it is being terminated.
Confused about what??? The color of the wires in the cable are totally irrelevant to anything done using cables with RJ-45 connectors on each end. What is important is that the cable be straight through if that's what you need, or crossover, if that's what you need. I will never see the colors in the cables.
Again, the only difference is the color of the wires in the cables. You can use either type of cable and they are identically the same unless you cut one open and look at the colors.
Who cares? The vast majority of my uses are static. It was plugged in five years ago and is still working. Or in this case, the 6 inch cable will be plugged and unplugged once a day. Being so short, there's little chance of a tangle which is how the latches get damaged.
Again,, not a concern, since this will only be used by the technicians who have been instructed in the operation of the unit. No phone jacks in the lab anyway.
You are confusing specification revisions indicator letters, with "pin and pair assignments" known as T568A and T568B. They have nothing to do with one another. The two pin/pair assignments (T568A and T568B) have to do with where circuit pairs 2 and 3 are on the connector. T568A and T568B reverse them. But this is only a matter of wire color inside the cable, so it has zero affect on the electrical performance. If you aren't making the cables, you have no need to know, or care about those colors.
Search your documents for T568A and T568B. Also, the spec would appear to be up to D, according to Wikipedia. It would seem TIA-568-B is very different from T568B.
Oh, it works fine; 100baseT used two-level signalling, one pair, and 1000baseT went to five-level signalling, four pairs at a time, to get an order of magnitude speedup. But, because part of that speedup was using up the noise margin (from two-level to five) and the rest was paralleling multiple (independently clocked) paths, it doesn't need any more bandwidth than 100baseT; so, all the Cat5 and Cat5e wire was immediately compatible. The termination accuracy and crosstalk minimization gets a tad more important.
1000baseT checks the pairs for connectivity, so an old crossover cable... might just work, or a two-pair cable even. It's compatible, so it can fall back to two-level and work with the 10baseT protocols, and with a media adapter, that means it can talk to old thinwire (10base2) or thickwire (10base5) subnets.
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