HP StorageWorks 16-EL HP StorageWorks Zoning V3.1.x/4.1.x User Guide (AA-RS26C - Page 60
The Effect of Zoning on RSCN Delivery
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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