See Auto-negotiation for a general discussion on network negotiations.
On HP-UX, you can check the link by issuing the following commands:
$ lanscan
Hardware Station Crd Hdw Net-Interface NM MAC HP-DLPI DLPI
Path Address In# State NamePPA ID Type Support Mjr#
0/0/0/0 0x00306E09612B 0 UP lan0 snap0 1 ETHER Yes 119
$ lanadmin -x 0
Current Speed = 100 Full-Duplex Auto-Negotiation-ON
If the auto-negotiation failed, you can manually set the NIC by issuing the following commands:
$ lanadmin -X 100FD 0
WARNING: an incorrect setting could cause serious network problems!!!
Driver is attempting to set the new speed
Reset will take approximately 11 seconds