ch. 8 Implementing Ethernet Virtual LANs Flashcards
What is 802.1Q
IEEE trunking protocol
how does 802.1Q work?
tags each frame with the VLAN ID and can support up to 4094 realistically
What is the normal range of VLAN IDs
1 - 1005
What is the extended range of VLAN IDs
1006 - 4094
What is the special VLAN ID on each trunk and how does it work
the native VLAN (VLAN 1) 802.1Q doesn’t add a header to this frame and the receiving switch takes that frame as a message to the VLAN 1
What is the purpose of the native VLAN
To support connections to devices that do not understand trunking
What do you need in order to send packets between VLANs
Router or a Layer 3 switch - multilayer switch
What are the steps to configure VLAN
Configure a new vlan and then assign interfaces
How do you configure a vlan
use the vlan-id command in global config mode to create the VLAN and to move the user into VLAN config mode
[optional] Use the name command in VLAN config mode to list a name for the vlan
How do you assign an access interface
use the interface command in global config mode to move into interface config mode for each desired interface
use the switchport access vlan command in interface config mode to specify the vlan number
[optional] use the switchport mode access command in inheritance config mode to make this port always operate in access mode
What is VTP and how does it work
VLAN Trunking Protocol - advertises each VLAN configured in one switch(with the vlan number command) so that all other switches in the campus learn about that VLAN
How do you disable VTP
use the command vtp mode transparent or vtp mode off
How do you create a Trunk between two vlans
use the switchport mode trunk on both sides of an interface between two switches in interface mode
What is DTP and what does it do
Dynamic Trunking Protocol - used to negotiate forming a trunk between two cisco devices
What command allows you to define the admin trunking mode
switchport mode
what does the switchport command access do
Always act as an (nontrunk) port
What does the switchport command trunk do
Awlays act as a trunk port
What does the switchport command dynamic desirable do
Initiates negotiation messages and responds to negotiation messages to dynamically choose whether to start using trunking
What does the switchport mode command dynamic auto do
Passively waits to recieve trunk negotiation messages at which point in the switch will respond and negotiate whether to use trunking
How to configure a voice vlan
vlan vlan-id - global conifg mode
interface type number -global conifg mode
switchport access vlan id-number - interface mode
switchport mode access - interface mode
switchport voice vlan - interface mode
What are the commands to check the status of trunking-related facts
show interfaces trunk and show interfaces switchport
what is vlan hopping
when frames from one vlan are sent over to another vlan when there is a native vlan mismatch
