Cisco WS-C6506 - Default VTP Version 3 Configuration

10-21
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 10 Configuring VTP
Default VTP Version 3 Configuration
Note You should configure VTP version 1 and VTP version 2 switches as clients to allow them to work
properly with VTP version 3. See the “Limitations” section on page 10-21 for more information.
• A VTP version 3 switch can detect VTP version 1 and VTP version 2 switches and send a
scaled-down version of its database on a per-trunk basis in VTP version 2 format only. VTP
version 1 switches move to VTP version 2 mode without any configuration assistance.
• A VTP version 3 switch never sends any VTP version 2 packets on a trunk unless it first receives a
legacy VTP version 1 or VTP version 2 packet on the trunk. This situation forces legacy neighboring
switches to keep advertising their presence on the link. If a VTP version 3 switch does not receive
a legacy packet on a trunk for a certain period of time, it is considered to be a VTP version 3-only
trunk and does not advertise a scaled-down version of the VLAN database or MST database on the
trunk anymore.
• Even when advertising a VTP version 2 database on a trunk, VTP version 3 keeps sending VTP
version 3 updates through the port. This situation allows two kinds of neighbors to coexist on the
trunk.
• A VTP version 3 switch can modify reserved VLANs 1002–1005; however, these VLANs are set to
their default in the scaled-down database in VTP version 2 format.
• A VTP version 3 switch never accepts a configuration from a VTP version 1 or VTP version 2
neighbor.
Limitations
The limitations of VTP version 3 are as follows:
• Two VTP version 3 regions can communicate only over a VTP version 1 and VTP version 2 region
in transparent mode.
• Leaving a server in a VTP version 2 region so that it will receive its VTP information from a VTP
version 3 region could cause a problem. If a configuration change occurs in the VTP version 1 and
VTP version 2 region, the revision of the database may become higher than the one that is generated
by the VTP version 3 region, and the updates from the VTP version 3 region may be ignored.
Note We recommend that you set all switches in the VTP version 1 and VTP version 2 region to
client and reset their revision number (do a reload or change the domain name back and
forth).
• A VTP version 2 region that is connected to two different VTP version 3 regions may receive
contradictory information and keep swapping its database to the VTP version 3 region that has the
highest revision number at any given time. We do not recommend this type of configuration.
• Enabling VTP pruning on a VTP version 3 switch enables pruning only on the switch that you enable
it on. VTP pruning is not propagated as it is with VTP version 1 and VTP version 2.
Default VTP Version 3 Configuration
Table 10-2 shows the default VTP version 3 configuration.