Two commands you can use to verify your trunk configuration are:
#show running-config
#show interfaces [interface-num] switchport | trunk
Using the trunk keyword with the show interfaces command gives information
about the trunk link:
# show interfaces fastethernet 0/1 trunk
Port Mode Encapsulation Status Native vlan
Fa0/1 desirable n-802.1q trunking 1
Port Vlans allowed on trunk
Fa0/1 1-150