Zoning is a logical grouping of ports that are allowed to communicate with each other. Hard zoning and soft zoning refer to enforcement techniques for zones in a Fibre Channel network, rather than a method of defining a zone.
Hard zoning is a zoning mechanism for blocking communication between devices that are not members of the same zone [*1]. Attributes of hard zoning include:
- Preventing a host from accessing a device it is not authorized to access.
- Checking each frame before it is delivered to a zone member and discards it if there is a zone mismatch.
Soft zoning is a method of zoning that limits information about devices or depends on a device's own access restrictions to limit communication with other devices. An example of soft zoning is Name Server zoning whereby the name server restricts responses to only those devices which are in the same zone [*1]. Attributes of soft zoning include:
- Preventing hosts from discovering unauthorized target devices.
- Ensuring that the name server does not return any information to an unauthorized initiator in response to a name server query.
- Does not prohibit access to the device. If an initiator has knowledge of the network address of a target device, it does not need to query the Name Server to access it, which could lead to undesired access to a target device by unauthorized hosts.
In a Fibre Channel fabric, zoning enforcement methods are vendor and implementation specific. For example, Brocade Fabric OS will use hard zoning for zones that are defined exclusively with <domain, portID> or exclusively with WWN. Fabric OS will use soft zoning for zone definitions that use a mixture of <domain, portID> and WWN [*2]. This varies by switch model, so check the switch manual for the zone enforcement method used on your switch model for different zone configuration.
As zoning enforcement might vary by switch vendor or model it is important to refer to the documentation to determine if hard or soft zoning method will be used for a given configuration.
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