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? -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
TIA/EIA 568 A vs. B
Started by ●November 4, 2022
Reply by ●November 5, 20222022-11-05
On Friday, November 4, 2022 at 6:22:03 PM UTC-7, Ricky wrote:> 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.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.
Reply by ●November 5, 20222022-11-05
On Saturday, November 5, 2022 at 2:24:29 AM UTC-4, whit3rd wrote:> On Friday, November 4, 2022 at 6:22:03 PM UTC-7, Ricky wrote: > > 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. > 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? -- Rick C. + Get 1,000 miles of free Supercharging + Tesla referral code - https://ts.la/richard11209
Reply by ●November 5, 20222022-11-05
On Saturday, 5 November 2022 at 08:13:43 UTC, Ricky wrote:> On Saturday, November 5, 2022 at 2:24:29 AM UTC-4, whit3rd wrote: > > On Friday, November 4, 2022 at 6:22:03 PM UTC-7, Ricky wrote: > > > 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. > > 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. John
Reply by ●November 5, 20222022-11-05
On Saturday, November 5, 2022 at 5:15:17 AM UTC-4, John Walliker wrote:> On Saturday, 5 November 2022 at 08:13:43 UTC, Ricky wrote: > > On Saturday, November 5, 2022 at 2:24:29 AM UTC-4, whit3rd wrote: > > > On Friday, November 4, 2022 at 6:22:03 PM UTC-7, Ricky wrote: > > > > 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. > > > 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!" -- Rick C. -- Get 1,000 miles of free Supercharging -- Tesla referral code - https://ts.la/richard11209
Reply by ●November 5, 20222022-11-05
On Saturday, November 5, 2022 at 1:13:43 AM UTC-7, Ricky wrote:> On Saturday, November 5, 2022 at 2:24:29 AM UTC-4, whit3rd wrote:> > 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???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.> > 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?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.> 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?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.
Reply by ●November 5, 20222022-11-05
On Saturday, November 5, 2022 at 5:33:26 AM UTC-4, whit3rd wrote:> On Saturday, November 5, 2022 at 1:13:43 AM UTC-7, Ricky wrote: > > On Saturday, November 5, 2022 at 2:24:29 AM UTC-4, whit3rd wrote: > > > > 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??? > 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.What wiring are you having to check??? Don't you just plug in the cables and be done with it?> > 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? > 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.Yeah, someone explained that elsewhere, thanks.> > 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? > 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 think the CAT5e cables won't work for 1000baseT, even with all 8 wires populated, no? It kinda annoys me that they didn't just run the pairs on adjacent pins. But now that I know, it won't be a problem. -- Rick C. -+ Get 1,000 miles of free Supercharging -+ Tesla referral code - https://ts.la/richard11209
Reply by ●November 5, 20222022-11-05
On 11/4/2022 9:21 PM, Ricky wrote:> 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? >https://www.omnisecu.com/basic-networking/tia-eia-568-standards.php
Reply by ●November 5, 20222022-11-05
On 11/4/2022 11:24 PM, whit3rd wrote:> All 'normal' patch cables are 568B, so that's the only spec I'd ever want to use.+42 You also want to be sure to be buying connector terminations that carry the matching color code, lest folks get even MORE confused.> POE, I'm not sure of.When power is delivered over the data pairs (Orange/Green), polarity is important. So, you want to know whether you've adopted 568A or B. Unless you are always probing an 8P8C by pin number (and never actual conductors). The "spare pairs" (Blue/Brown) feed diode bridges so don't really care about polarity (unless you're a stickler for standards). But, 8P8C's are shit connectors. Even shrouded, the damn latches seem to find a way to snap off ("plastic fatigue"?) And, its too easy to encounter something with an 8P8C (or 4P4C, 6P6C) that will mechanically mate yet "misbehave" electrically (to the detriment of one or the other halves of the mated circuit -- witness the pains PoE goes to to safeguard against a *phone* being plugged into an 8P8C PoE drop!)
Reply by ●November 5, 20222022-11-05
On 11/5/2022 2:15 AM, John Walliker wrote:> High-frequency attenuation is > also better on the higher-numbered types which typically use slightly thicker wire.That's an understatement! Running CAT6 is tedious compared to CAT5. It's far less flexible and has a larger bend radius. It's the modern day equivalent of orange hose, in that sense! :-/