A network switch, which is participating in VLAN Trunking Protocol (VTP), can have three different modes.
- • Server Mode.
- • Client Mode.
- • Transparent Mode.
How does VLAN tagging work?
VLAN Tagging, also known as Frame Tagging, is a method developed by Cisco to help identify packets travelling through trunk links. The Trunk Links allow frames from all VLANs to travel throughout the network backbone and reach their destination regardless of the VLAN the frame belongs to.
What is VLAN transparent mode?
The VTP Transparent mode is something between a VTP Server and a VTP Client but does not participate in the VTP Domain. In Transparent mode, you are able to create, modify and delete VLANs on the local switch, without affecting any other switches regardless of the mode they might be in.
What is tagged port?
A port is a ‘tagged port’ when the interface is expecting frames containing VLAN tags. An example of this is when two switches are connected, and pass tagged traffic. Cisco switches use the term ‘trunk’ to refer to a tagged port. The sender will send a frame with a VLAN tag.
How does the VLAN tag work on a switch port?
When the frame reaches the switch port, the switch will add the VLAN tag. The switch port is configured with a VLAN ID that it will put into the tag. Most switch ports will use this mode by default, with VLAN ID 1. When a frame leaves an untagged port, the switch strips the VLAN tag from the frame.
What is the difference between VLAN tagging and untagged packets?
Note: Depending on the vendor, an untagged port that receives a tagged packet will drop that packet, except the VLAN tag matches the VLAN configured on that port. On the other hand, some devices understand and participate in VLAN tagging.
How to enable VLAN privilege mode in switch?
Switch>en (“en” command is used to enable privilege mode) Switch# (“#” indicates you have successfully entered the privilege mode) Switch#vlan database (“vlan database” command is used to enter in database mode) % Warning: It is recommended to configure VLAN from config mode, as VLAN database mode is being deprecated.
What is the IEEE 8021q standard for creating a VLAN tag?
While different vendors have their own proprietary method for creating this tag (e.g. the now deprecated Cisco ISL protocol), a standard supported by most networking devices for supporting VLANs on Ethernet networks is the IEEE 802.1Q standard. 802.1Q adds a 32-bit field (4 bytes) inside an Ethernet frame.
