VLAN Trunking Protocol abbreviated as VTP is a very useful protocol developed by Cisco to create, manage and maintain VLANs for a a large network with many interconnected switches to maintain consistency throughout the network. It is a protocol that propagates the definition of Virtual Local Area Networks (VLAN) on the whole local area network (LAN). Switches in a LAN use VLAN trunking protocol (VTP) to communicate among themselves about VLAN configuration. VTP carries VLAN information to all the switches in a VTP domain by sending an advertisements over 802.1Q, and ISL trunks. It can manage the addition, deletion, and renaming of VLANs from a central point without any manual intervention. For a small network, VLAN trunking configuration is easy to manage, however, VLAN trunking for large networks with many interconnected switches can be a very difficult and tedious task.
Currently there are three version of VLAN Trunking Protocol (VTP) namely Version 1, Version 2, and Version 3. VTP Version 1 and VTP Version 2 functions almost similar. The enhancements made on VLAN Trunk Protocol (VTP) V3 includes protection from unintended database overrides during insertion of new switches, support for VLAN numbers up to 4096, support for interaction with VTP Version 1 and VTP Version 2, Support for a structured and secure VLAN environment (Private VLAN, or PVLAN), option of clear text or hidden password protection, configuration option on a per port base instead of only a global scheme and optimized resource handling and more efficient transfer of information.
Benefits of VLAN Trunking Protocol
- Better network management: VTP lowers the possible inconsistencies in configuration that normally comes after modifications are made in a network. The inconsistencies may lead to the security violations.
- Maintains consistency: VTP offers the benefit of maintaining configuration consistency throughout the network. It utilizes trunk frames for managing any changes made to the VLANs in that particular network which attained through the use of a central switch found in the server mode.
- Manages Cisco switches: VTP provides an effective method of managing Cisco switches like one group for configuration purposes. If the VTP is enabled on a Cisco switch, creating a VLAN on a single switch makes the VLAN accessible to all the switches in that VTP domain.
Benefits of VTP version 3 (VTPv3)
1) No Automatic Setup of VTP Domain: In VTP version 2, a factory default switch which receives a VTP message will automatically configure to be in the VTP domain. In the real world, automatic configuration could be scary. VTPv3 thus forces manual configuration.
2) Support for all VLAN Numbers: VTP can be used for propagating all VLAN numbers in accordance with the IEEE. This is the probably the most important feature of VTPv3.
3) Security: The VTP domain password is secured in the database and in transmission.
4) Database Propagation Fixed: VTP version 3 allows only a specific device in a domain, a primary server, to update other devices. Only one server per domain can be a primary server logically.
5) MST Configuration: The VTPv3 database is extensible. It allows information to be exchanged and replicated.
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