A trunk-port is a port configured to pass frames including broadcast frames through multiple VLAN switches. Its main purpose is to carry multi-vlan traffic through single port using unique identifying tags. You could use universal 802.1Q protocol or Cisco proprietary Inter-Switch Link (ISL) protocol.
To view Trunk Ports on Cisco switch, use
show interface trunk command
SW03#show interface trunk
Port Mode Encapsulation Status Native vlan
Fa0/1 on 802.1q trunking 1
Fa0/3 on 802.1q trunking 1
Fa0/4 on 802.1q trunking 1
To learn how to configure Trunk Port on Cisco switch, see
How To Setup A Trunk Port On Cisco Switch? instruction.
