The VLAN Tagging Policy is a system-level setting for ensuring that systems are assigned to their appropriate VLAN. By default, this setting is contained in the System VLAN Tag Group named Switches, is available to the System VLAN Tag Group named Other Systems, and is available to all System Resource Groups.
A networked environment may consist of many separate networks, each having many VLANs. One VLAN may have the same name (VLAN ID) as a VLAN in another network. Identically named VLANs do not create problems across different networks; however, when these VLANs are discovered and placed into a single topology, conflicts arise.
If you do not use the VLAN Tagging Policy setting, the IP Manager will combine any discovered VLANs that have identical names into a single VLAN of that name; for example, VLAN-1. And systems that belong to the identically named but locally distinct VLANs will be represented in the modeled topology as belonging to VLAN-1. Because of this incorrect representation in the modeled topology, the IP Manager root-cause and impact analysis will produce inaccurate results.
If you do use the VLAN Tagging Policy setting, the IP Manager will distinguish any discovered distinct VLANs that have identical names by adding a unique tag to the name of each of the distinct VLANs. And systems that belong to identically named but distinct VLANs will be represented in the topology as belonging to distinct VLANs. Because of this correct representation in the modeled topology, the IP Manager root-cause and impact analysis will produce accurate results.