Newbie question re back-to-back serial cables
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Posted by on October 17, 2007, 1:33 pm
Please log in for more thread options you shouldn't disconnect back-to-back serial cables from the interfaces while the routers are powered on. Is there any truth to this? Thanks for any info. | ||||||||||||||||
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Posted by Trendkill on October 17, 2007, 5:54 pm
Please log in for more thread options Not sure what you mean by back to back serial cables, but I see no reason why this warning is legit, and have never encountered such a problem in any of my labs back in the day. Perhaps Merv or Mike has some additional input. | ||||||||||||||||
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Posted by headsetadapter.com on October 17, 2007, 9:38 pm
Please log in for more thread options With old routers you may burn the port. Also, if you plug the cable
"on-fly", your controller may fail - cable itself defines what type of interface to initialize. For example, if you connect V.35 cable, the same controller will initialize the same port as V.35 interface, but if you plug RS-232 cable, the port will be RS-232 port. Also there is a difference if controller is initialized as DTE or DCE. And all of this is determined during bootup, depending on that is connected to the serial port. Good luck, Mike CCNP, CCDP, CCSP, Cisco Voice, MCSE W2K, MCSE+I, Security+, etc. CCIE R&S (in progress), CCIE Voice (in progress) ------ Headset Adapters for Cisco IP Phones www.ciscoheadsetadapter.com www.headsetadapter.com > I've just started working in my Cisco lab and I heard somewhere that
> you shouldn't disconnect back-to-back serial cables from the > interfaces while the routers are powered on. Is there any truth to > this? > > Thanks for any info. | ||||||||||||||||
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Posted by Scott Perry on October 22, 2007, 10:35 am
Please log in for more thread options The word "should" puts uncertianty into this. I lean more towards this
being a relatively safe activity. In ten years of working with 2500 and 2600 series up to 3600 and 7200, I have plugged/unplugged serial interface cables while both ends were powered on and not burned up any equipment. I would have cared less about the 2500 series than controllers for the 3600 and 7200. When the links are not up, a software shutdown/no-shutdown often clears links if problems are experienced. I have even witnessed a serial cable getting plugged in upside down which bent the plug housing, but after reverting the cable back the connection still worked. It is probably not a bad idea to keep devices off when connecting and disconnecting cables unless it creates unneccesary inconvenience. If you are wanting to connect or disconnect a serial cable and might have to wait until network downtime or a maintenance period, I would support just connecting a cable or disconnecting a cable while the device is powered on to get things done. It depends on how prudent and cautious you and your company want to be in facing the risk. In my experience, I have had no more trouble with connecting/disconnecting while powered on than I have with a PS/2 style keyboard or mouse cable on a PC. -- =========== Scott Perry =========== Indianapolis, Indiana ________________________________________ > I've just started working in my Cisco lab and I heard somewhere that
> you shouldn't disconnect back-to-back serial cables from the > interfaces while the routers are powered on. Is there any truth to > this? > > Thanks for any info. | ||||||||||||||||
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> you shouldn't disconnect back-to-back serial cables from the
> interfaces while the routers are powered on. Is there any truth to
> this?
>
> Thanks for any info.