The current Configuration Revision Number as known by
the local device for this management domain when
managementDomainVersionInUse is version1(1) or
version2(2).
If managementDomainVersionInUse is version3(4), this
object has the same value with vtpDatabaseRevisionNumber
of VLAN database type.
This value is updated (if necessary) whenever a VTP
advertisement is received or generated. When in the
'no management-domain' state, this value is 0.