Understanding Trunk Ports
Usually, you configure a switch as a member of a specific VLAN. This automatically
associates all of the regular Ethernet traffic received on that port with that VLAN.
Sometimes, however, you may want a single port to receive traffic from multiple VLANs.
A switch port that accepts traffic from multiple VLANs is known as a trunk port.
To differentiate between the different VLANs, each packet is tagged with a specific VLAN
identifier. This identifier informs the switch to which VLAN the traffic needs to be forwarded.
By using trunk lines on your switch, your Security Appliance can send and receive traffic
from multiple VLANs using only a single physical interface.