This notification is sent whenever a switch sends or receives a Build Fabric (BF) or a ReConfigure Fabric (RCF) message on a VSAN. A switch can receive or issue a BuildFabric (BF) or a ReConfigureFabric (RCF) message under following conditions: - A new link causes two disjoint fabrics in a VSAN to merge into one fabric. The sent/received message is BF if the Domain ID lists on the disjoint fabric does not overlap and it is RCF if they overlap. - An upsteam principal ISL which connects to Principal switch and other switches in a VSAN fails. BF is issued to see if there is an alternative path to the Principal Switch. If not paths exit, then an RCF is issued. - A switch asks for a different set of Domain IDs than the currently assigned list, the Principal switch would issue an RCF. The notification is not sent if a 'dmNewPrincipalSwitchNotify' notification is sent for the same transition. This notification contains the vsanIndex of the VSAN on which RCF was issued.