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    <title>Performing External Loopback Tests </title>
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<a name="wp1195907"> </a><h1 class="pTitle">
Performing External Loopback Tests

</h1>
<a name="wp1195908"> </a><p class="pBody">
You can run manual loopback tests to identify hardware errors in the data path in the switching or 
services modules, and the control path in the supervisor modules. External loopback tests send and 
receive FC2 frames to and from the same port or between two ports. 

</p>
<a name="wp1195909"> </a><p class="pBody">
You need to connect a cable (or a plug) to loop the Rx port to the Tx port before running the test. If you 
are testing to and from the same port, you need a special loop cable. If you are testing to and from 
different ports, you can use a regular cable. This test is only available for Fibre Channel interfaces.

</p>
<a name="wp1377314"> </a><p class="pBody">
Choose <span style="font-weight: bold">Interface</span> &gt; <span style="font-weight: bold">Diagnostics</span> &gt; <span style="font-weight: bold">External</span> to perform an external loopback test from Device Manager.

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

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