[PLUG] Troubleshooting DHCP...

[Mike Connors]

Galen Seitz wrote:
> 10BASE-T and 100BASE-TX only require 2 pairs.  There was a version of 
> 100Mbit that required 4 pairs(100BASE-T4), but I believe it is 
> obsolete.  Anyone still using 100BASE-T4 would almost certainly be 
> aware of that fact.
> http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair
> http://en.wikipedia.org/wiki/Fast_Ethernet#100BASE-T4
>
> Gigabit ethernet(1000BASE-T) requires 4 pairs.). 
In its typical configuration, 100BASE-TX uses one pair of twisted wires in each direction, providing 100 Mbit/s of throughput in each direction (full-duplex). Which means that the link could be good, but the cable wouldn't support full-duplex mode. So in theory the NIC might support full-duplex but the Ethernet cable w. a broken wire doesn't. And then you have a duplex mis-match between the 2 end devices. You drop in the 10-base-T hub, which most likely doesn't support auto-neg / full-duplex and it magically works. If I recall, the Orig Poster said he did see Ethernet errors...