HP StorageWorks XPath OS 7.4.X Administrator Guide (AA-RVHDD-TE, February 2006)
86 Creating and maintaining zones
Zoning terminology
A zone is a specified group of fabric-connected devices, also called zone objects. Any device or zone
object connected to the fabric can be included in one or more zones. Zone objects within a zone can
communicate only with other zone objects in the same zone.
After zoning is enabled, if a device is not explicitly defined in a zone, that device is isolated and is
inaccessible to other devices in the fabric.
Zone objects are grouped into zones, and zones are grouped into a zone configuration. Zones can
overlap; that is, a zone object can belong to more than one zone and a fabric can have multiple zones.
You can create multiple zone configurations; however, only one configuration can be enabled in the fabric
at a time.
Zoning enforcement
To design, configure, and administer Fibre Channel zoning on your fabric, you need to understand the
difference between a zone member specification and the mechanism used for zoning enforcement. XPath
OS supports two basic zoning enforcement mechanisms:
• Software-enforced zoning (also called soft zoning)
• Hardware-enforced zoning (also called hard zoning)
Soft zoning
In soft zoning, the Name Server, getting its information from the zone server, limits the targets returned to a
Fibre Channel initiator only to those that Fibre Channel initiator can communicate with (as specified by the
zoning configuration). This is the method required by the Fibre Channel standards FC-SW-2, FC-GS-3, and
FC-GS-4. If the Fibre Channel host bus adapters (HBAs) are standards-compliant, this method is reliable.
The standard requires that HBAs purge their address tables and query the Name Server upon receipt of a
Fibre Channel registered state change notification (RSCN). This ensures that all entries in the HBA address
table correspond to members of the same zone of which the HBA is a member.
With soft zoning, an initiator that is a member of a zone has access to the names and addresses of other
members of the zone only, and so cannot address frames to devices outside of the zone.
XPath OS soft zoning is industry standards-based. It is compatible with hard zoning, with Fibre Channel
switch zoning implementations, and with WWN and domain,port member types.
You can specify soft zones with the configureZoning command.
Hard zoning
Hard zoning enforcement must be used in those situations in which the HBAs are not standards-compliant,
for example, when your hardware predates the standards. Since hard zoning is not standards-based,
different implementations are possible, but hard zoning is frequently implemented by switch ports
maintaining lists of allowed source and destination ID pairs. If a frame S_ID/D_ID pair is not on a port’s
list of allowed pairs, the frame is not transmitted.
In XPath OS hard zoning, the frame source and destination addresses are compared to allowed addresses
at the MP Router ingress F_Port or FL_Port (for devices directly attached to the MP Router) or at the egress
F_Port or FL_Port (for devices directly attached to a Fabric OS-based switch). The details of hard zoning
enforcement are not needed to configure zones or for routine administration of the MP Router; however,
see Appendix A, “Hard zoning background,” if you would like to learn more about hard zoning
enforcement.
The MP Router hard zoning implementation is compatible with other HP StorageWorks switches.
Zone server compatibility
The zone server maintains the zone configuration information used for both soft and hard zoning, so a
fabric can simultaneously use both hard and soft zoning. The zone server distributes the soft zoning
information to the Name Server and the allowed S_ID/D_ID pairs to the appropriate ports for hard zoning.
XPath OS hard zoning can coexist with other implementations of hard zoning, although XPath OS hard
zoning cannot necessarily share zoning information with other hard zoning implementations.