VLAN Trunking Protocol (VTP)

Like Catalyst IOS, Nexus NX-OS supports VLAN Trunking Protocol (VTP) to ease in the administration of VLAN creation, deletion, and naming throughout the LAN. However, there are a few key functional differences between NX-OS’s implementation of VTP and most other platforms.

NX-OS supports VTP mode off. In this mode, all received VTP updates are filtered, and the VLAN database is only locally significant. This is unlike VTP Transparent mode, which passes VTP updates between interfaces, even though its database is locally significant as well. Another difference, as of the version in this example, is that Nexus 5K does not support VTP pruning. Also note that although extended VLANs can be configured in all four VTP modes, they still cannot be advertised by either servers or clients because there is currently no support for VTP version 3.

The end result is that it is fairly easy for the VLAN databases to become out of sync when there is a mix of VTP modes in the network, not to mention the same potential problems as in Catalyst IOS of mistakes in the configuration of VTP servers possibly deleting VLANs, or the entire VLAN database, in the entire network. For this reason, it is very typical that VTP is not used in Data Center LAN environments, although the feature is still technically supported.

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