> # About Overlay VSANs

> VSANs enable deployment of larger SANs by overlaying multiple logical SANs, each running its own instance of fabric services, on a single large physical network. This partitioning of fabric services reduces network instability by containing fabric reconfiguration and error conditions within an individual VSAN. VSANs also provide the same isolation between individual VSANs as physically separated SANs. Traffic cannot cross VSAN boundaries and devices may not reside in more than one VSAN. Because each VSAN runs separate instances of fabric services, each VSAN has its own zone server and can be zoned in exactly the same way as SANs without VSAN capability.

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