Wiping the configuration on multiple router models

Unanswered Question
Mar 10th, 2010

I have a total of (8) eight switches/routers that I need to wipe. None are connected to a network, and I am missing the cables that came with the devices.

  • 2 X Cisco 1700
  • 1 X Cisco 2500
  • 3 X Cisco 2600
  • 1 X Cisco 2801

  • 1 X Asanté IntraCore 3524

I'll have each router in front of me and I want to be able to plug each router into my laptop and log on. Does each model use a different type of cable configuration? Can I use a crossover from the laptop ethernet port into the router ethernet or FastEther port and then hook up a console cable from my serial port into the console port for all. I've seen crossover and rollover cables mentioned, so I'm confused.

I have this problem too.
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Leo Laohoo Wed, 03/10/2010 - 13:00

You can use a Roll-Over cable.

For ethernet cable, the rule of thumb to use between a client and a router is always a cross-over cable (because they are both Layer 2 devices).  The exception to the rule is when either one happens to be MDI/MDI-X capable.  Of the routers you mentioned, only the 2801 is MDI/MDI-X.  I can't answer for your client and this "Asanté IntraCore 3524".

It's easier to use the Roll-Over cable particularly if you want to perform password-recovery.

james-moss Thu, 03/11/2010 - 09:50

Thanks for the info. A coworker handed me a DB9 Female to RJ45 Male Light Blue Cable. It's has the Cisco name stamped on it, and the part number is LL97744. I plugged it into my laptop COM1 and into the console and used Hyperterminal to connect. So far so good. I'll try it with Putty next.

However, while researching the cable I came across this little bit of information from a cable reseller:

This is NOT the standard Cisco roll-over console cable and will NOT work with routers and switches such as the 2600 series and 2900 series.

I guess this means that I'll need to find a different cable for the three 2600 series models?

Leo Laohoo Thu, 03/11/2010 - 13:21

Hi James,

First off, if you can console to one router it won't stop you from consoling to the next.  Secondly, hold on to your laptop like it's vital.  You have no idea how many old laptops with console ports are left.  Don't get me started about the USB-to-Serial contraptions.  Most of the time they don't work.

TYLER WEST Mon, 04/26/2010 - 07:58

Your cable reseller is blowing smoke.  The light blue cable has a DB9 on one end and an RJ-45 on the other end, right?  It will work for most any Cisco console port that is an RJ-45.  Now you might run across an old 7200 or something it might not work for but pretty much all of the modern Cisco switches and routers it will.  Now, it isn't technically the "rollover" cable because that cable actually has an RJ-45 on both ends.  You don't see too many of them anymore.  Those hearken from the day when you would get the rollover cable AND a DB9 to RJ-45 adapter in the box.  Sometimes you even got a DB25 to RJ-45 adapter in the box as well.  The light blue cable is really the same as the DB9 to RJ-45 adapter PLUS the rollover cable all combined into one unit.  All of those cables are designed to work with the console port.  For the routers you can use the rollover cable to connect from the AUX of the router port to the CON of any other Cisco device and use reverse telnet to get to it.  There is a little more to that configuration and you can easily find the details on the Internet.

The "crossover" cable is used to connect two Ethernet ports together.  Not many years ago it was required when connecting two switches together.  Now many of the switches can autosense MDI/MDI-X and switch their transmit and receive pins to compensate.  There are a few routers that can do it as well.  You can always try a straight-through Cat5 cable to see if it will work and, if it doesn't, switch to a "crossover".  A straight-through can always be used between a router and a switch or a PC and a switch.  However you MIGHT have to use a "crossover' if you are connecting switch to switch or router to PC.

Just about any of these cables can be made with some Cat5, plugs, and a crimper.  Cisco documents the pinouts.  In a nutshell a rollover cable is mapped as follows:

1 <> 8

2 <> 7

3 <> 6

4 <> 5

5 <> 4

6 <> 3

7 <> 2

8 <> 1

You can see why they call it a rollover because you "roll" the conductors over to the other side.  You can use Cat 5, 3, or even flat-satin for this since it is a serial cable.

The Ethernet "crossover" cable is called such because you are crossing over the transmit and receive pairs of the cable.  I don't have the pinout handy but look out on the Internet for a description of EIA/TIA 568A and 568B pinouts and you simply wire it as 568A on one side of the cable and 568B on the other side.  You must use Cat5 for this and, if doing GigE, should use Cat5E.

Ganesh Hariharan Wed, 03/10/2010 - 21:34

I have a total of (8) eight switches/routers that I need to wipe. None are connected to a network, and I am missing the cables that came with the devices.

  • 2 X Cisco 1700
  • 1 X Cisco 2500
  • 3 X Cisco 2600
  • 1 X Cisco 2801

  • 1 X Asanté IntraCore 3524

I'll have each router in front of me and I want to be able to plug each router into my laptop and log on. Does each model use a different type of cable configuration? Can I use a crossover from the laptop ethernet port into the router ethernet or FastEther port and then hook up a console cable from my serial port into the console port for all. I've seen crossover and rollover cables mentioned, so I'm confused.

Hi,

Check out the below link for more information on how to connect a router with console cable.

http://www-tss.cisco.com/eservice/compass/common/tasks/task_console_port_connect.htm

Hope to help !!

Remember to rate the helpful post

Ganesh.H

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