Re: half vs full duplex

Thomas Massano ( )
Sat, 22 Aug 1998 10:23:10 -0400

Md, the key to it is, does the hub and or cabling support full duplex. Most
cards have this feature as "auto Sensing". I only use 3com Nics and
Hubs/Switches at the sites i setup. And I always spec out the cabling for
cat5 4 pair per jack. Wiring for the future, Gigabit Ethernet requires 4
pair. Depending on the type of card or technology, you may require 4 pair
cables instead of two in 100BASE-T. As someone else pointed out, if you
turn full duplex on, and your wiring or hub does not support it, it WILL
cause problems on your net. Here is some info on 100BASE-T from 3com's site:

Support for 100BASE-TX or 100BASE-T4 Power of 100 Mbps performance without
the cost of installing new cable. T4 provides flexibility to support 100
Mbps on 4 pairs of Category 3, 4, or 5 UTP cable. TX provides 100 Mbps
throughput using two pairs of Category 5 UTP. Both TX and T4 support
Category 3, 4, or 5 UTP cable for 10BASE-T mode

At 06:18 PM 8/21/98 , you wrote:
>couple of networks i got offer the choice of half or full duplex. They
>defaulted to half so I never changed them cuz I wasn't sure what would
>happen if I set them to full and the other end didn't support it. I have
>looked but never found the answer.
>My question is :
>if i set a network card to full and its not supported will it run in half or
>not work at all.?