CAT 6A cables - reverse polarity?

[Zorlac]

I bought some CAT 6A cables and now my onboard intel network adapter reports the the cable's polarity is reversed. If I use my old CAT 5 cable, then the polarity shows as normal.

Everything seems to working fine. Did I happen to get bad cables though?

[zanzabar]

u have a cross over cable, they are for connecting a router to another router or switch to switch or computer to computer, your NIC should be smart enough to work around it, but u just have to switch 2 wires and u can look on wiki to find the ones to switch

[Zorlac]

I figured it was something like that *sigh*

How did this happen? Here is what I bought (it did not mention x-over):

http://www.amazon.com/gp/product/B001LMZPI8/ref=ox_ya_oh_product

[zanzabar]

patch means crossover. and next time go to home depot they are way cheaper unless thats a huge cable but it dosnt give a length .

your driver should be smart and fix it for u but if not use the diagrams to decross it or u can buy an adapter but that may lower performance
http://en.wikipedia.org/wiki/Ethernet_crossover_cable

[SoulsCollective]

Modern NICs will have no performance degradation when using crossover. I don't think older ones did either, but I can't vouch for that. There's no point in replacing it, if anything, it's more useful than regular - because you can directly connect two PCs without a switch in between if one of the PCs has an older NIC or shoddy drivers that auto-switch.

[Serra]

Modern PC's will all support auto-switching from straight-through to crossover pinouts. There's no performance loss, older cards/devices just couldn't do it. It's just a matter of changing which pins transmit and which receive electronically.

[SoulsCollective]

Modern PC's will all support auto-switching from straight-through to crossover pinouts. There's no performance loss, older cards/devices just couldn't do it. It's just a matter of changing which pins transmit and which receive electronically.Thanks for confirming :)

[Zorlac]

Thx guys!

...I seriously never knew a "patch" cable was the same as a "cross-over" cable. I figured cross-over cables would always be specifically called that in descriptions.

[3Z3VH]

A patch cable is NOT a crossover. Patch cables are meant to go from a patch panel to a switch. The proper term for a cable that is meant to connect two network components, is either Crossover or Uplink cable. When connecting a network component to a computer, it will be called a Patch cable, or Straight through cable.

While Serra is correct that it should not make a difference in this case, it does make a difference when running longer lengths of cable. Each of the different pairs of wires in your standard RJ-45 are twisted at different TPI (twists per inch) so they do not interfere with each other, and so they are more resistant to RMI/EMI interference. When using a longer run of cabling, you are meant to keep the cable straight-through (not crossover) in order to minimize the interference you will receive.

[zanzabar]

every time ive gotten a patch cable it was xover

[Serra]

While Serra is correct that it should not make a difference in this case, it does make a difference when running longer lengths of cable. Each of the different pairs of wires in your standard RJ-45 are twisted at different TPI (twists per inch) so they do not interfere with each other, and so they are more resistant to RMI/EMI interference. When using a longer run of cabling, you are meant to keep the cable straight-through (not crossover) in order to minimize the interference you will receive.

While it is true that there are different twists per pair, you're only switching between two transmit pairs (each side has 1 set of transmit pairs) - not a transmit to a ground pair, for example. They should each have the same number of twists (I believe - please correct me if I'm wrong). I don't believe it makes any difference at all.

[Zorlac]

I have narrowed down my issue. There is nothing wrong with my cables. If I bypass my router with all my cables and just run straight from my cable modem, then the polarity is normal.

Running from modem to router and then to computer shows reverse polarity.

Here is the kicker...

If I turn off gigabit mode on my adapter and turn on 10/100 mode, then the polarity shows normal. WTF?

Does anyone know what is going on?

Linksys Cisco WRT610N V1 router
Motorola SB6120 DOCSIS 3.0 cable modem
Intel PRO 1000/PL 82573L onboard ethernet adapter with Windows 7 RC x64 driver v 14.2
Belkin CAT6A cabling

[3Z3VH]

Your modem is considered a "computer" when it comes to the use of cabling, so if you are using a crossover cable, it will show up as not crossed over when connecting two computers directly (seriously, try plugging that same cable into the back of another computer, it will not warn you about reverse polarity).

For Gigabit Ethernet over copper, you are using all eight conductors in the wire, and thus, need to cross over both pairs if creating a 568 standard gigabit cable.

As mentioned, with such a short length of cable, you really don't need to worry about the reversed polarity. There are precious few devices that do not use the "optional feature" in the 1000BaseTX/T4 standard for Auto Crossover. Your connection should work just fine, regardless of the reverse polarity warning.