Dot1Q
mplementing Cisco IP Switched Networks (300-115)
dot1Q:
Dot1Q is IEEE 802.1Q, the standard for trunking encapsulation. On Cisco switches, you configure dot1q on trunk ports which allow tagged frames to be transported on a trunk link, allowing multiple VLANs to traverse through one link. This extends the VLANs across the network. dot1Q trunks use VLAN 1 as the default native VLAN. 802.1Q also adds a 4-byte tag into the Ethernet frame for VLAN tagging.
Description and Commands:
Configure a VLAN trunk interface
(config)# interface fa 1/5
Configure VLAN encapsulation SW
SW(config-if)# switchport trunk encapsulation isl dot1q
Verify the trunk configuration
SW# show interfaces fa1/5 switchport
Verify the trunk configuration
SW# show interfaces fa1/5 trunk
Verify the trunk configuration
SW# show interfaces trunk