User`s guide

242 Implementing an Open IBM SAN
3.4.3 Understanding INRANGE name server zoning
In contrast to hard zoning, there is no actual physical segmentation of fabrics with
name server zoning.
Instead, a name server table is used to implement that type of zoning.
Name server tables store information about nodes that have logged into the
fabric. Name server zones restrict the access of affected ports to this information.
All unzoned nodes have full access to the name server table.
This means that zoned ports logging into a fabric will only get name server table
information of other ports which are part of the same name server zone.
Unzoned ports are considered as being part of an orphan zone which is not
visible to users, but allows communication for all unzoned nodes.
Because this kind of zoning relies on the proper usage of FCP protocol
commands, it is also widely called soft zoning.
Name server zoning gives better flexibility then hard zoning:
򐂰 A particular director port can be part of multiple name server zones.
򐂰 The granularity of ports to build a name server zone is only one port.
򐂰 Name server zone members need not be physically adjoining each other.
򐂰 The change of name server zones does not enforce a port re-login of affected
ports.
However, since name server zoning relies on the correct usage of FCP
commands, there is still a risk that malfunctioning nodes would affect other ports
even if these other ports are not members of the same zone.
Due to its strength and flexibility, name server zoning is widely used in open
systems environment.
Name server zoning rules
There are rules that must be adhered to:
򐂰 INRANGE name server zoning refers to physical director ports. A type of
name server zoning pointing to WWNs of attached nodes will be available in
the future.
򐂰 Each name server zone needs to get a unique number and a name.
򐂰 As many as 256 zones are possible in a fabric.
򐂰 Name server zones cannot cross the boundaries of defined hard zones.
򐂰 Director ports which have private nodes attached to it need to be set to TL
mode. name server zoning is not effective for TL_Ports.