Trunking

Question 1

Which trunking protocol(s) support native vlans

Answer 1

802.1q does, ISL does not.

Question 2

What is the size of the tag when a frame is tagged by 802.1q trunking?

Answer 2

4 bytes

Question 3

What happens when a frame is crosses a trunk port on the native vlan

Answer 3

It is sent untagged.

Question 4

What is ISL

Answer 4

Inter-switch protocol is a cisco proprietary standard of trunking. it is important to note that many newer cisco devices no longer support ISL.

Question 5

What is the difference between trunk mode active and mode desirable

Answer 5

With auto the other side must initiate the trunking. This is effectively passive. With desirable this is active trunking and the trunk will be established if the other side has not been set to access or nonegotiate

Question 6

Are frames encapsulated when they cross a trunk port?

Answer 6

Only with ISL. 802.1q does not encapsulate.

Question 7

What must be done before configuring a port as a trunk port

Answer 7

Trunk encapsulation must be configured with this command
#switchport trunk encapsulation {dot1q | isl | negotate}

Question 8

What command is used to change the native vlan of a trunk

Answer 8

switchport trunk native vlan [vlan id]