Cisco IOS switches
1. To disable port negotiation:

Console> enable
Console# configure terminal
Console(config)# interface gigabitethernet mod_mun/port_num
Console(config-if)# speed nonegotiate
2. To verify port negotiation:

Console# show interfaces gigabitethernet mod_mun/port_num
3. To enable port negotiation (should you remove the gigabit Observer product from the switch):

Console(config)# interface gigabitethernet mod_mun/port_num
Console(config-if)# no speed nonegotiate