When you manually select the speed and duplex mode on a Cisco Systems Catalyst 2948G multi-layer local area network (LAN) switch, you may experience slow network performance with a Microsoft Windows 2000-based computer.
To resolve this issue, if you manually set the switch to a certain speed or duplex mode, manually configure the network adapter to use the same settings.
This behavior is by design.
When you manually set the Catalyst 2948G to 10 Full, 10 Half, 100 Full, or 100 Half, you automatically disable NWAY autodetection of duplex mode. When the network adapter is set to Auto speed/Auto Duplex, the network adapter cannot detect the duplex mode of the switch, and therefore defaults to 10 Half duplex.