foreword
At work, we may encounter such a problem. There are many switches in the company , and basically each switch needs to be configured with the same VLAN for intercommunication. In the case of many VLANs, such a workload It is very large, so the VTP technology mentioned today must be used. It only needs to be configured on one switch and can be synchronized to other switches, which greatly reduces the amount of switch configuration!
Note: VTP protocol is Cisco's proprietary protocol
1. What is VTP?
VTP (VLAN Trunking Protocol: Virtual Local Area Network Trunk Protocol), which is a Cisco proprietary protocol . In a large network, there will be multiple switches and multiple VLANs. If you create VLANs on each switch, it will be a heavy workload. The VTP protocol can help administrators reduce these boring and heavy tasks . The administrator sets up one or more VTP Servers in the network, and then creates and modifies VLANs on the Servers. The VTP protocol will notify other switches of these modifications, and these switches will automatically update the VLAN information (VLAN ID and VLAN Name).
2. The role of VTP
Usually, we need to keep the VLAN database synchronized in a group of switches in the entire enterprise network to ensure that all switches can read the relevant VLAN information from the data frame for correct data forwarding. However, for large networks In other words, there may be hundreds of switches, and there may be dozens or even hundreds of VLANs on a switch. If only manual configuration by network engineers is a very large workload, it is also not conducive to future maintenance— — Every time a VLAN is added, modified or deleted, it needs to be deployed on all switches. In this case, VTP technology can be used to solve it.
To use VTP, a VTP management domain must first be established . Switches in the same management domain share VLAN information, and a switch can only participate in one management domain. Switches in different domains cannot share vlan information.
3. Working principle of VTP
VTP is a messaging protocol that uses Layer 2 frames to transfer VLAN information between switches , known as VTP advertisements . With VTP, the VLAN configuration can be modified centrally on one switch, and the modification will be automatically propagated to other switches in the network, thereby achieving the consistency of VLAN configuration. The premise of realizing this function is that these switches belong to the same VTP domain.
1. VTP domain
A VTP domain, also known as a VLAN management domain , consists of more than one interconnected switches that share a VTP domain name. In other words, a VTP domain is a group of switches with the same VTP domain name and interconnected through trunk links.
Conditions for using VTP: First, a VTP domain must be established, switches in the same management domain share their VLAN information, and a switch can only participate in one VTP domain.
Switches in different domains cannot share VTP information.
Requirements for VTP domains: Each switch in the domain must use the same VTP domain name, whether through configuration or automatically learned by the switch, Catalyst switchesmust be adjacent, that is, adjacent switches musthave the same domain name. All Catalyst switchesmust be configured as trunk links.
If any of the above conditions are not met, the VTP domain cannot be connected and information cannot be transmitted across the split.
2. VTP mode
The VTP mode determines how the switch processes and advertises VTP information.
There are three VTP modes: server mode, client mode and transparent mode.
① Server mode (Server) The switch acting as a VTP server is responsible for the management of VLAN information in its domain. The VTP server can create, delete or modify VLANs , and send VTP notifications to the outside . At the same time, the VTP server will also learn VTP with the same domain name. Notice information. By default, the switch is in VTP server mode. Each VTP domain has at least one server to create, delete or modify VLAN and provide VLAN information.
②Client Mode (Client) Switches in this mode do not allow administrators to create, delete or modify VLANs . They listen to VTP announcements from other switches in the domain and modify their own VTP configurations accordingly.
③Transparent mode (Transparent) The switch in VTP transparent mode does not participate in VTP. When the switch is in transparent mode, it can create, delete or modify local VLANs, but it does not advertise its own VLAN configuration information to the outside . VTP announcements are only forwarded and will not learn and change their own VLAN information.
Fourth, the advantages of VTP management
1. Simplify management
Using VTP can simplify VLAN management because it can automatically transmit VLAN information to the entire network , enabling administrators to manage and configure VLANs more efficiently.
2. Reduce misuse
Through VTP, administrators can avoid misoperations when manually configuring VLAN information on different switches , thereby improving network reliability and stability.
3. Improve scalability
VTP can help administrators quickly expand the network scale . When new switches join the network, they will automatically obtain VLAN information without manual configuration.
4. Reduce network traffic
By using VTP, administrators can avoid unnecessary broadcast traffic , because VTP packets are sent only when VLAN information changes, which can effectively reduce network traffic.