Date: 09/03/07 (IT Professionals)    Keywords: no keywords

Perhaps one of you can shed some light on this for me. It's not exactly a problem, but just a mystery that doesn't make sense to me.

Say you have a dedicated box being used as a Ghostcast server. Said box has a gigabit NIC card in it. If I plug one end of a 3ft Cat6 patch cable into this box, and the other into a similar computer with an identical NIC that I want to deploy an image to, I get a Ghostcasting speed of approximately 500MBytes/min.

We have a Cisco gigabit switch available to use (a Catalyst 5000G, specifically). If I plug 6 computers into the switch (including the server) and assign the same IP/Subnet range to all of them, I get a Ghostcasting speed of nearly 2000MBytes/min. All cables are Cat6 and approximately the same length, and I'm spitting out exactly the same image.

I suspect that the speed difference is due to my using a patch cable and not a crossover; I'm aware that many cards will automatically correct this through hardware - would that slow it down? What does the switch do differently that speeds it up so dramatically? Why is that that plugging a short Cat6 cable directly between server and client is four times slower than 6 computers running through a gig switch? Thank you for any insight you provide.

~Elliot

Source: http://community.livejournal.com/itprofessionals/64207.html