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why Rollover cable

Hi,

sorry to ask this but...but many times i get this doubt whenever i have to connect to router console port.

why cisco still supplying rollover cables with db9 connecter pins on the other end,

now a days every system has multiple usb ports and we can directly connect console or aux to usb but we have to buy the serail to usb connecters and carry with us where ever we are going, if we forget that, thats all...we have to go to market and buy one serial to usb again.

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Accepted Solutions

Mohammed,

but i am asking console to usb not serial to usb,

That's my point precisely! You want "console to USB", meaning that the cable will have an USB end to plug into your PC, and something inside the Cisco router or switch that provides a console connectivity, and that something will need to have its own specific drivers. Even if it was a PL2303 or whatever, it would require a driver. There is no such thing as "plain communication over USB".

Best regards,

Peter

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10 Replies 10

cadet alain
VIP Alumni
VIP Alumni

Hi,

http://networkingnerd.net/2011/05/17/rollover-beethoven-usbs-in-town/

Regards

Alain

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Don't forget to rate helpful posts.

yeah i noticed the port on router but didn't tried it as i always carry rollover and serial to usb cables.

but i am asking can't cisco give us the same rollover cable with usb option instead of connecting the db9 end to serial to usb cable.

Peter Paluch
Cisco Employee
Cisco Employee

Hi Mohammed,

I am not a Cisco representative so this is just my personal opinion.

I believe that the primary reason is simply the legacy related to using the RS-232/DB9 interfaces and rollover cables. There is an immensely large installed base of Cisco products that were manufactured in times when RS-232 interface was still common on computers and notebooks. Making an abrupt change for new devices and equipping them only with a USB interface is probably going to make your life easier with these new devices but for all the remaining world that has not yet replaced all their routers and switches with the bleeding-edge models, this is not going to be helpful at all.

In addition, there is an important thing to consider - apart from a driver for your RS-232 interface in your PC, you do not need any additional driver to allow you to communicate with a device connected to it. It is very easy to just plug a device into a RS-232 port and you can immediately communicate with it. With USB, it is different - you need a driver for your USB host controller (which your OS normally has), but also you need to have a driver for any particular connected USB device, and this can be a problem. Even if the connected USB device is going to emulate a character-based serial interface, you need a driver for that, and this driver is going to different depending on what USB-to-serial controller is installed. You surely know this is true for all the USB-to-serial dongles. I get always angry when I plug my PL2303 converter into a Windows-based machine, and though several these dongles use the same chip, Windows always requests a specific driver for this dongle - not even mentioning the fact that Windows Vista and newer do not even have drivers for this type of dongle! And I am not even going to mention how many different USB-to-serial controllers are out there, and each of them has its own driver... Bless my Linux - it works all the time

So in fact, going with pure USB is going to be more problematic as this requires heavier driver support, and if you think across different platforms - Windows, Linux, BSD, MAC... that's a tough nut to crack. Simply adding a USB-to-serial cable instead of a rollover cable is not going to solve problems right away.

Best regards,

Peter

yes, i know the hassel for the drivers with windows

but i am asking console to usb not serial to usb,

if we are connecting one end to router console port and the other directly to our usb port than , we can have a cisco cable compatible driver perminantly with us.

Mohammed,

but i am asking console to usb not serial to usb,

That's my point precisely! You want "console to USB", meaning that the cable will have an USB end to plug into your PC, and something inside the Cisco router or switch that provides a console connectivity, and that something will need to have its own specific drivers. Even if it was a PL2303 or whatever, it would require a driver. There is no such thing as "plain communication over USB".

Best regards,

Peter

i know this is not going to happen soon, but getting damn irritatting when i i forget my serial to usb cable and i have to go and buy one.

anyway thank you for your patience..

In addition to Peter,s comments most new products come with a mini USB ports these day so you can go directly from your laptop to router using USB to USB but you have to buy the cable separately. It does not come in the Box

HTH

Sent from Cisco Technical Support iPhone App

Hi Reza,

That's exactly what the link I posted  in my reply was about

Regards

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.

Hi Alain,

Sorry, I couldn't get your link to open on phone before I replied.

My apologies

Reza

edmondfm1
Level 1
Level 1

If you have the serial to ethernet cable or DB9 to Ethernet cable that comes with your router, no need to buy DB9 to USB just go get DB9 Male to DB9 Male which will convert the Cisco default serial cable to Male that can be plug into any modern laptop. You can get them for like $12.99 in RadioShack.

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