|
|
Using VLAN Trunk Protocol (VTP), each switch advertises its management domain on its trunk ports, its configuration revision number, and its known VLANs and their specific parameters. A VTP domain is made up of one or more interconnected devices that share the same VTP domain name. A switch can be configured to be in only one VTP domain.
VTP servers and clients maintain all VLANs everywhere within the VTP domain. A VTP domain defines the boundary of the specified VLAN. Servers and clients also transmit information through trunks to other attached switches and receive updates from those trunks.
VTP servers either maintain information in nonvolatile random-access memory or access it using the Trivial File Transfer Protocol (TFTP). Using VTP servers, you can modify the global VLAN information using either the VTP Management Information Base (MIB) or the command-line interface (CLI). When VLANs are added and advertised, both servers and clients are notified that they should be prepared to receive traffic on their trunk ports. A VTP server can also instruct a switch to delete a VLAN and disable all ports assigned to it.
The advertisement frames are sent to a multicast address so they can be received by all neighboring devices, but they are not forwarded by normal bridging procedures. All devices in the same management domain learn about any new VLANs configured in the transmitting device. Because of this process, you need to configure a new VLAN only on one device in the management domain. All other devices in the same management domain automatically learn the configured information. VTP is transmitted on all trunk connections, including ISL, 802.10, and LAN Emulation (LANE).
A new VLAN is indicated by a VTP advertisement received by a device running VTP. Devices then accept the traffic of the new VLAN and propagate it to their trunks after adding the VTP-learned VLANs to their trunks. The VTP pruning protocol limits the extent of this forwarding to areas of the network where the VLAN extends, based on VLAN membership resident within the switch.
Using periodic advertisements, VTP tracks configuration changes and communicates them to other switches in the network. When a new switch is added to the network, the added devices receive updates from VTP and automatically configures existing VLANs within the network. VTP also dynamically maps VLANs across multiple LAN types with unique names and internal index associations. Mapping eliminates excessive device administration required from network administrators.
VTP establishes global configuration values and distributes the following global configuration information:
The VTP MIB provides the Simple Network Management Protocol (SNMP) instrumentation for the VTP, allowing the reading and setting of specific VTP parameters.
|
|