The Effect Of Zoning On Rscn Delivery - HP A7340A - Surestore FC 1Gb/2Gb Switch 16B User Manual

Zoning Concepts and Guidelines

The Effect of Zoning on RSCN Delivery

Whenever a change occurs in the nameserver, such as a device addition or removal
from the fabric, a registered state change notification (RSCN) is required to be
generated. In the absence of zoning, an RSCN is sent to all devices on the fabric.
Each device should then query the nameserver to determine how the membership
of the fabric has changed. This will happen even if the device change does not
affect the other devices. In large fabrics, this can result in a significant amount of
traffic being generated, although typically for only short time.
For instance, if a new initiator joins the fabric, there is little purpose in notifying
all the other initiators of the change. Initiators do not typically communicate with
each other. An equivalent situation exists with targets. As targets generally do not
communicate with each other, they have little use in being notified of the addition
or removal of another target.
Once zoning is implemented then only affected devices in the changed zone will
receive the RSCN. If devices are already aware of their zoned members, then they
will not receive an RSCN. Only devices that are affected by the change will
receive an RSCN. While all devices are supposed to handle RSCN traffic without
affecting normal operation, experience has shown that this is not always the case.
Thus, the overall stability of the fabric is increased when zoning is implemented.
60 Zoning Version 3.1.x/4.1.x User Guide