Dell PowerVault 56F (16P Fibre Channel Switch) - Manual (Page 24)

3-6 Dell PowerVault 5xF Switches Zoning Guide
With SNS zoning, a device can still be accessed if a requester knows (by some other
means) the WWN of the target. For this reason, the PowerVault 51F switch also
supports hardware-enforced zoning when physical fabric port numbers are used to
specify zones.

& $ 
Two databases are used by zoning—one for the zone configuration data and another
for the N_Port login data.
Zone configuration data is shown as the defined configuration by the cfgShow com-
mand and is stored in flash by the cfgSave command. This data is a replicated
database, and all fabric switches have a complete copy. When you save a configura-
tion, the switch where you entered the command forwards the change to all fabric
switches using a vendor-unique interswitch protocol.
N_Port login data is stored locally on each switch and is used to translate worldwide
names into physical fabric port numbers when worldwide names are used in zone
definitions. The zone checking procedure runs entirely on the local switch when a
match can be made by physical fabric port number alone. However, when a physical
fabric port number is not sufficient, the local switch must query the remote switch to
get login data. This data is then cached on the local switch until a state change notifi-
cation renders the data unusable.