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    <title>About iSNS Client Functionality </title>
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<a name="wp1091467"> </a><h1 class="pTitle">
About iSNS Client Functionality

</h1>
<a name="wp1091468"> </a><p class="pBody">
Internet Storage Name Service (iSNS) allows your existing TCP/IP network to function more effectively 
as a SAN by automating the discovery, management, and configuration of iSCSI devices. The iSNS 
client registers iSCSI portals and all iSCSI devices accessible through them with an iSNS server. All 
iSCSI devices (both initiator and target) acting as iSNS clients can register with an iSNS server. When 
the iSNS client is unable to register or deregister objects with the iSNS server (for example, the client is 
unable to make a TCP connection to the iSNS server), it retries every minute to reregister all iSNS 
objects for the affected interfaces with the iSNS server.

</p>
<a name="wp1091469"> </a><p class="pBody">
The iSNS client functionality on each IPS interface (Gigabit Ethernet interface or subinterface or 
PortChannel) registers information with an iSNS server. 

</p>
<a name="wp1091470"> </a><p class="pBody">
Once a profile is tagged to an interface, the switch opens a TCP connection to the iSNS server IP address 
(using the well-known iSNS port number 3205) in the profile and registers network entity and portal 
objects; a unique entity is associated with each IPS interface. The switch then searches the Fibre Channel 
name server (FCNS) database and switch configuration to find storage nodes to register with the iSNS 
server.

</p>
<a name="wp1091471"> </a><p class="pBody">
Statically mapped virtual targets are registered if the associated Fibre Channel pWWN is present in the 
FCNS database and no access control configuration prevents it. A dynamically mapped target is 
registered if dynamic target importing is enabled. See the <a href="ciscsi004.html">&quot;Presenting Fibre Channel Targets as iSCSI 
Targets&quot; topic</a> for more details on how iSCSI imports Fibre Channel targets.

</p>
<a name="wp1091475"> </a><p class="pBody">
A storage node is deregistered from the iSNS server when it becomes unavailable when a configuration 
changes (such as access control change or dynamic import disabling) or the Fibre Channel storage port 
goes offline. It is registered again when the node comes back online.

</p>
<a name="wp1091476"> </a><p class="pBody">
When the iSNS client is unable to register or deregister objects with the iSNS server (for example, the 
client is unable to make a TCP connection to the iSNS server), it retries every minute to reregister all 
iSNS objects for the affected interfaces with the iSNS server. The iSNS client uses a registration interval 
value of 15 minutes. If the client fails to refresh the registration during this interval, the server will 
deregister the entries.

</p>
<a name="wp1091477"> </a><p class="pBody">
Untagging a profile also causes the network entity and portal to be deregistered from that interface.

</p>
<a name="wp1091478"> </a><p class="pBodyAutonumNoRule">
<strong>Note	&nbsp;&nbsp;&nbsp;</strong> The iSNS client is not supported on a VRRP interface.

</p>
<hr /><br><p class="pBody">Copyright 2010-2013, Cisco Systems, Inc. All rights reserved.</p> 

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