Excuse for not having any references to back this up: Over the older KVMs the VGA signal is sent analog from the dongle to the KVM. To do this, the horizontal sync/vertical sync and colors are separated and sent over different pairs.
With the original cat5 spec, the pairs in the cable all had the same twist. Because of this, the different parts of the video signal traveled along the wire at about the same speed. With cat5e or Cat6, the twists are different. This causes the timing of the signals to be off - and the problem gets worse the longer the cable - to the point where it will be unusable. Newer VGA extenders (that still use analog signals) have circuits that correct for this. For example: http://www.aten-usa.com/products/KVM/KVM-Extenders/PS2-KVM-Extender~CE350.html -Eric -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Robert Hajime Lanning Sent: Friday, March 18, 2016 9:52 PM To: [email protected] Subject: Re: [lopsa-discuss] KVM's and PDU's On 03/18/16 18:30, Doug Hughes wrote: > All of the important electrical properties for Cat6 should have no > impact on Serial. I'm pretty sure it is not a normal "serial" signal. I don't know about *recent* KVMs, but as of about 6 years ago, the dongles output a very analog signal on the Cat5. All the high powered digitization of the VGA signal was done inside the KVM unit. Over longer runs, your screen started to look like the old 1950's TVs... This was with Dell IP based KVMs. Avocent like, but not quite. The dongles looked identical, but were not interchangeable. -- Mr. Flibble King of the Potato People http://www.linkedin.com/in/RobertLanning _______________________________________________ Discuss mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/discuss This list provided by the League of Professional System Administrators http://lopsa.org/ _______________________________________________ Discuss mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/discuss This list provided by the League of Professional System Administrators http://lopsa.org/
