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What it's a Rollover Cable
- Thread starter kaosk
- Start date
Identifying a Rollover Cable
You can identify a rollover cable by comparing the modular plugs at the two ends of the cable. When you hold the plugs side by side, with the tab at the back, the wire connected to the pin on the outside of the left plug should be the same color as the wire connected to the pin on the outside of the right plug.
example:
RJ45--------RJ45
PIN 1 PIN 8
2 7
3 6
4 5
5 4
6 3
7 2
8 1
hope it helps.
cbum
Uh... say what???
I don't think so.
A "rollover" cable is not simply an end to end mirror of the wiring order. This is because TX and RX are not in the middle of the RJ45 biscuit, and both pairs need to be surrounded by inductive grounding.
A "straight thru" cable (meaning non-rollover) should look the same on both ends. Following the CAT-V standard, the order should be:
White Orange, Orange, White Green, Blue, White Blue, Green, White Brown, Brown.
On a rollover cable, one end should be normal (as above), and the other end should be:
White Green, Green, White Orange, Blue, White Blue, Orange, White Brown, Brown.
This translates to the following pin order for a rollover cable:
1 -> 3
2 -> 6
3 -> 1
4 -> 4
5 -> 5
6 -> 2
7 -> 7
8 -> 8
I've never particularly cared for the choices of color in the standard, but I do care about following standards... especially on those occasions when I've had to figure out someone else's mess.
Hope this helps.
Regards,
oldschool
I don't think so.
A "rollover" cable is not simply an end to end mirror of the wiring order. This is because TX and RX are not in the middle of the RJ45 biscuit, and both pairs need to be surrounded by inductive grounding.
A "straight thru" cable (meaning non-rollover) should look the same on both ends. Following the CAT-V standard, the order should be:
White Orange, Orange, White Green, Blue, White Blue, Green, White Brown, Brown.
On a rollover cable, one end should be normal (as above), and the other end should be:
White Green, Green, White Orange, Blue, White Blue, Orange, White Brown, Brown.
This translates to the following pin order for a rollover cable:
1 -> 3
2 -> 6
3 -> 1
4 -> 4
5 -> 5
6 -> 2
7 -> 7
8 -> 8
I've never particularly cared for the choices of color in the standard, but I do care about following standards... especially on those occasions when I've had to figure out someone else's mess.
Hope this helps.
Regards,
oldschool
In the Cisco world,, there are TWO types of "rollover" cables.. one is a true rollover.. which is as cbum says, one end is flipped. The other to be precise is a "Cross-over" cable which flips the pairs in a normal CAT3-5 cable to reverse the transmit and receive side much like you would do on a RS232 cable.
Given the post is in a Cisco Forum and "rollover" was specified, I think Cbum has the "more" correct answer based on the skimpy facts at hand.
Just my 2.5 cents
Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin
Given the post is in a Cisco Forum and "rollover" was specified, I think Cbum has the "more" correct answer based on the skimpy facts at hand.
Just my 2.5 cents
Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin
Dont feel alone ;-) what makes you think you have the lock on the brain fade moments... it's that wonderful feeling you get just your brain registers the "click" of the enter key when you suddenly wake up and know you really didnt want to do that 
Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin
Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin
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