Cisco WS-C6506 Software Manual page 256

Chapter 10 Configuring VTP
Understanding How VTP Version 3 Works
Figure 10-4 VTP Version 3: Partitioned VTP Domain
Domain Cisco Domain Cisco
Primary Server X Primary Server Y
Partitions exist because of discrepancies in the domain configuration that cannot automatically be
resolved by VTP. Partitions are the result of a misconfiguration or an independent configuration of a
temporarily disconnected part of the domain. This behavior of VTP version 3 protects the domain from
accepting a conflicting configuration after the insertion of a misconfigured switch. If a new switch is
added to a domain, it will not propagate its configuration until you manually designate it as the new
primary server.
The primary server for a VLAN instance can be a different server than the primary server that is set for
an MST instance. Using two primary servers in this case does not cause partitions.
For information on using the takeover mechanism to reconfigure partitioned VTP domains, see the
"Reconfiguring a Partitioned VTP Domain" section on page 10-16.
Reconfiguring a Partitioned VTP Domain
Partitioning of a VTP domain is specific to the instance; one instance may be partitioned while another
might not be partitioned. In VTP version 3, you are required to remove any partitions because the
protocol cannot determine which primary server has the final, desired configuration. Figure 10-5 shows
a VTP domain that has been divided into four partitions for one specific VTP instance.
In Figure 10-5, server X has the correct configuration for the domain. To reconfigure this partitioned
VTP domain, you need to issue a takeover message from server X to the entire domain, advertising
server X as the new primary server for this specific instance. All switches in the domain will lock onto
primary server X and accept only the instance configuration updates that are initiated by server X. All
switches in the domain synchronize their VTP configuration to server X for that instance.
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
10-16
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