A trunk is always a point to point link between two network devices Only devices like swtitches,ip phones can handle trunked traffic pcs aswell with a vlan supporting NIC.
If a switch doenst have a VLAN configured (doenst know it) he forward it so all the Switches need to have the VLANs configured so they can forward to eachother
Cisco trunk functions:
- Allow more than one VLAN
- Extend the VLAN across the entire network
- By default, supports all VLANs
- Supports 802.IQ (Vlan tags) trunking