According to the specs of the D-Link DGS-1100-16 Easysmart 16-Port Gigabit Switch at amazon.com:
IEEE 802.3 compliant IEEE 802.3u compliant; Supports half/full-duplex operation (half at 10/100 Mbps, full at 1000 Mbps) Auto-negotiation; Auto MDI/MDIX; IEEE 802.3x Flow Control supports Full-Duplex mode; IEEE 802.3az compliant [emphasis added]
Why is it that a switch would support full duplex operation at 1000 Mbps, but not at the lower speeds? It seems that it would be easier/cheaper/more logical to support FD at lower speeds than at high speeds. So if they're going to the effort of making the switch FD at high speeds, why not at lower speeds, too? What am I missing?
11 Answer
It is a bad description on the page, Per page 35 in the manual for the switch (it's an anonymous login) the device support Half and Full duplex at 10/100 but only Full duplex at 1000.
Port Functions
10/100/1000BaseTX ports compliant with the following standards:
- IEEE 802.3
- IEEE 802.3u
- IEEE 802.3ab
- Supports Full/half-Duplex operations at 10/100Mbps
- Supports Full-Duplex operation at 1000Mbps
As @plugwash points out, half duplex gigabit is possible. But [almost] no such device exists. You will not run into in regular real world setups.
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