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Normally i connect to the console port with a RJ45 -> Serial cable. (Using a SerialtoUSB adapter if im in my notebook).

But for curiosity... Is there any way to connect to a console port using a RJ45-RJ45 cable pluging it in my Ethernet Port, instead of the USB one?

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What about serial port servers? – Nick Kavadias Jul 23 '10 at 5:37
up vote 2 down vote accepted

Short answer: No.

Longer answer: It's an RS-232 serial interface, not an Ethernet interface.

Side note: I've just checked a Cisco serial cable and confirmed that it's an 8P8C connector; but RJ45 is a different beast entirely.

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Console cables are rollover cables. Pin 1 goes to pin 8. Pin 2 goes to pin 7. Etc. Regular network cables are straight through. Pin 1 goes to pin 1. Pin 2 goes to pin 2. etc.

Also, the communication is completely different. The console port uses serial communication. Ethernet ports use ethernet communication. I'm sure somebody smarter than me will come along and explain the difference.

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I'm not smarter than Jason, but I can say that the signals used for serial communication and for ethernet are drastically different. Serial over RJ45 uses one line for sent data, one for received, 4 for flow control, one for ground... For 10/100BaseT, one pair of wires is used for sent data, one for received, and the other 4 aren't used at all.

Here's a link that shows RS232 on various connectors including RJ45.

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I would call that smarter than me :-) – Jason Berg Jul 23 '10 at 5:48
Different set of voltages, too. Ethernet over twisted pair uses differential signalling, RS-232 uses common ground with multiple data wires. – Andrew Jul 23 '10 at 6:07

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