if the board uses a fiber interface, these keywords are ignored, and the fiber interface board only links at 1000 mbps full-duplex.
for copper-based boards, the keywords interact as follows:
the default operation is auto-negotiate. the board advertises all supported speed and duplex combinations, and it links at the highest common speed and duplex mode if the link partner is set to auto-negotiate.
if speed = 1000, limited auto-negotiation is enabled and only 1000 mbps is advertised (the 1000baset spec requires auto-negotiation.)
if speed = 10 or 100, then both speed and duplex must be set. auto-negotiation is disabled, and the autoneg parameter is ignored. partner must also be forced.
the autoneg parameter is used when more control is required over the auto-negotiation process. when this parameter is used, speed and duplex must not be specified. this parameter is a bitmap that specifies which speed and duplex settings are advertised to the link partner.
note that setting autoneg does not guarantee that the board will link at the highest specified speed or duplex mode, but the board will link at the highest possible speed/duplex of the link partner if the link partner is also set to auto-negotiate. if the link partner is forced speed/duplex, the adapter must be forced to the same speed/duplex.