> # Information About VSANs

> A VSAN is a virtual storage area network (SAN). A SAN is a dedicated network that interconnects hosts and storage devices primarily to exchange SCSI traffic. In SANs, you use the physical links to make these interconnections. A set of protocols run over the SAN to handle routing, naming, and zoning. You can design multiple SANs with different topologies.

> With the introduction of VSANs, the network administrator can build a single topology containing switches, links, and one or more VSANs. Each VSAN in this topology has the same behavior and property of a SAN. A VSAN has the following additional features:

> - Multiple VSANs can share the same physical topology.
> - The same Fibre Channel IDs (FC IDs) can be assigned to a host in another VSAN, thus increasing VSAN scalability.
> - Every instance of a VSAN runs all required protocols such as FSPF, domain manager, and zoning.
> - Fabric-related configurations in one VSAN do not affect the associated traffic in another VSAN.
> - Events causing traffic disruptions in one VSAN are contained within that VSAN and are not propagated to other VSANs.

> This section describes VSANs and includes the following topics:

> - VSAN Advantages
> - VSANs Versus Zones
> - VSAN Configuration
> - About VSAN Creation
> - About Port VSAN Membership
> - About the Default VSAN
> - About the Isolated VSAN
> - Operational State of a VSAN
> - About Static VSAN Deletion
> - About Load Balancing
> - About Interop Mode
> - About FICON VSANs

> The four switches in this network are interconnected by trunk links that carry both VSAN 2 and
> VSAN 7 traffic. The inter-switch topology of both VSAN 2 and VSAN 7 are identical. This is not a requirement and a network administrator can enable certain VSANs on certain links to create different VSAN topologies.

> Without VSANs, a network administrator would need separate switches and links for separate SANs. By enabling VSANs, the same switches and links may be shared by multiple VSANs. VSANs allow SANs to be built on port granularity instead of switch granularity. The criteria for creating such groups differ based on the VSAN topology:

> - VSANs can separate traffic based on the following requirements:
> - Different customers in storage provider data centers
> - Production or test in an enterprise network
> - Low and high security requirements
> - Backup traffic on separate VSANs
> - Replicating data from user traffic
> - VSANs can meet the needs of a particular department or application.

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