VTP (VLAN Trunking Protocol) operates on Layer 2 of the OSI model. It configures and manages VLANs on Cisco network devices.
What is the VTP Protocol Used in Switches in a Network?
In a physical network, many switches link VLANs. Each VLAN requires manual configuration on each switch. It maintains the connection between VLANs.
As the organization grows, the addition of extra switches occurs. Each new switch requires manual configuration with VLAN information. Still, the process of managing the workload and the workload becomes longer.
The VTP feature automatically sends VLANs configured on a central switch to other devices in a domain. Central management provides control over the switches in the network. It sends the created configurations to all devices with the same VLAN and domain members.
When devices are physically inaccessible, administrators can easily configure other devices’ configurations. It is possible thanks to the VTP protocol. VTP stands for VLAN Trunking Protocol. It simplifies VLAN configuration across switches. As a result, it ensures efficient network management. The VTP protocol helps administrators remotely manage switches. So, it streamlines network administration tasks.
How Does VTP Work?
VTP performs editing or deleting VLANs. It does this from a central switch. This main switch manages all switches in the network. As a result, it saves time. VTP prevents separate settings for each device. Administrators can work with VLANs efficiently. It enhances network management efficiency.
It is easier to configure VLANs on a single switch in a network. Also, it applies to both large and small environments. But, configuring all VLANs on all switches can be troublesome. To simplify this process, we create a VTP domain structure. Other devices subscribe to this domain. So, all switches synchronize settings efficiently.
In short, Trunking is a Cisco-proprietary Layer 2 protocol. It enables switches to exchange VLAN information. It ensures a synchronized VLAN database from a central point in the network. Additionally, it sends updates to all devices via multicast.
Switches use VTP version 1 by default. But, when you want to change the version, you can use the “vtp version” command in the device’s general configuration mode.
Its primary advantage is that it reduces the need for manual network configuration. Additionally, it allows easily scalable switched network solutions.
What Does VTP Do?
The developers developed VTP to propagate VLANs in massive network infrastructures. It maintains the integrity of VLANs. Also, it enables central distribution, deletion, or modification of VLAN information. Additionally, this simplifies management tasks. Moreover, it ensures consistent VLAN configuration across the network.
In short, it simplifies network administration. Also, it can automatically deploy VLANs across many switches. Additionally, this occurs after configuring specific parameters on each switch.
But, enabling or configuring this feature in networks with a single switch is not recommended. Additionally, set the switch to Transparent mode. Moreover, it is advisable.
Note: Network devices transmit VTP messages only over trunk interfaces.
VTP Modes
The trunking protocol has three primary operating modes. These are Server, Client, and Transparent.
Server
Switches have this mode as the default mode. In this mode, users can create, change, or delete VLANs. Additionally, it provides flexibility in network configuration.
A Switch configured in Server mode announces its configuration to all Switches in the domain. Other switches will synchronize their VLAN database with the server.
To configure this mode, you must configure at least one device in the environment as a Server. Additionally, you can use authentication in this mode.
Client
The switch in this mode cannot delete, change, or create VLANs. In this mode, it can only retrieve VLAN information from the switch configured as a VTP Server.
A VTP Client saves VLAN information. It’s for the entire domain. However, this information gets cleared upon device restart and retrieved again.
Transparent
You cannot create, delete, or change VLANs in transparent mode. But you can synchronize them with other devices on the network. A Switch operating in this mode can only change local VLAN information.
This mode doesn’t receive or apply VTP updates. It only sends received updates to Client devices in the same domain. Furthermore, this ensures consistent VTP communication within the field. VTP version 2 delivers updates regardless of whether the devices are in the same environment.
VTP Pruning
The pruning feature saves bandwidth. For instance, a Switch with the same domain controls its ports based on VLAN information from the server device.
But, if there is no port for relevant VLAN information, the receiving device discards packets because its ports don’t match the VLAN.
When an incompatible VLAN structure exists, VTP enables Pruning. It prevents excessive bandwidth consumption by devices sending packets to unrelated VLANs. As a result, network performance improves.
Message Types
Summary Advertisements
Messages sent to neighboring switches contain the device’s domain information and VTP revision. When receiving the message, the device compares its local and domain information.
If the domain name does not match, the package will be cancelled. Otherwise, it compares the revision number. In such cases, it requests that the balanced package’s revision number be higher than the local value.
Subset Advertisement
Messages contain an up-to-date VLAN database. Subset messages increase the revision number after the change. So, these messages ensure accurate information exchange.
Advertisement Request
When the conditions are met, the Summary Advertisement message and Switches request VTP information. Additionally, this ensures proper communication between components.
VTP Join
The domain name, password, and version number meet the requirements. Next, the join message type propagates VLANs between server and client devices.
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