Connecting a USB laptop to a RJ45 serial port

Question

We are about to get our first managed switch at work (Procurve 2520G-24-PoE), and this lowly programmer gets to put on his admin hat and try to configure it. The switch has an RJ45 serial port for console access. My laptop has USB ports but no serial port. In fact, there isn't a single computer in the office with a serial port.

I've seen USB-to-DB9 adapters, but I need to go from USB to RJ45 (serial). How would I go about accomplishing this? Do I need two adapters? Will USB-to-DB9 and then DB9-to-RJ45 work?

Thanks in advance.

To piggy back off your question - yesterday I was looking at a funky Toshiba AC100 notebook running Android and thinking it would be perfect as a lightweight "KVM" for onsite work - anyone know if Android can support these USB serial cables? The driver discs with them usually only include Windows drivers... — Mitch Miller, Sep 08 '10 at 02:31
possible duplicate of [Does a USB to RJ-45 console cable exist?](http://serverfault.com/questions/156508/does-a-usb-to-rj-45-console-cable-exist) — Dennis Williamson, Sep 08 '10 at 09:30

score 4 · Answer 1 · answered Sep 08 '10 at 02:14

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The USB to DB9 serial and DB9 to RJ-45 works perfectly fine. I use just that combination (with a standard Cisco DB9->RJ-45 serial cable) all the time.

answered Sep 08 '10 at 02:14

Helvick

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Same here - I use a USB-to-DB9 cable, and then use the black DB9-to-RJ45 that comes in the Procurve box. – Mitch Miller Sep 08 '10 at 02:28
That clarifies things perfectly. Thanks for the help! – Sep 08 '10 at 13:44

Warner · Answer 2 · 2010-09-08T02:15:04.160

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The manual is published on the Internet. Two methods are suitable for connecting to the switch.

The switch should come with a RJ45 to DB9 connector, which you can use any standard DB9 to USB adapter if you only have USB. This is the preferred method.

Also, the switch will acquire an IP address from DHCP or Bootp servers by default. Once a lease is acquired, you can connect to the switch's IP via either telnet or a Web browser.

edited Sep 08 '10 at 02:15

answered Sep 08 '10 at 02:02

Warner

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You can also make sure that your PC is that DHCP server, by plugging in your PC directly to the switch and running a DHCP server (I use Tftpd32 Service Edition; it supports TFTP for firmware upgrades, as well as DHCP, Syslog, DNS - very handy for troubleshooting). – Mitch Miller Sep 08 '10 at 02:35

EEAA · Answer 3 · 2010-09-08T02:14:54.530

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My laptop doesn't have any serial ports either, so I frequently use a USB->Serial dongle in combination with a DB9->RJ45 adaptor. Works just fine.

edited Sep 08 '10 at 02:14

answered Sep 08 '10 at 02:09

EEAA

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That clarifies things perfectly. Thanks for the help! – Sep 08 '10 at 13:43

Connecting a USB laptop to a RJ45 serial port

3 Answers3