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    <title>Failover Scenarios for PortChannels and FSPF Links  </title>
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    <blockquote>
    <a name="top"></a>

    
    


<a name="wp1072912"> </a><h1 class="pTitle">
Failover Scenarios for PortChannels and FSPF Links 

</h1>
<a name="wp1072916"> </a><p class="pBody">
The SmartBits traffic generator was used to evaluate the scenarios displayed . Two links between switch 
1 and switch 2 exist as either equal-cost ISLs or PortChannels. There is one flow from traffic generator 
1 to traffic generator 2. The traffic was tested at 100 percent utilization at 1 Gbps in two scenarios: 

</p>
<div class="pSmartList1"><ul class="pSmartList1">
<a name="wp1072920"> </a><li class="pSmartList1">Disabling the traffic link by physically removing the cable. 
</li>
<a name="wp1072924"> </a><li class="pSmartList1">Shutting down either switch 1 or switch 2 . 
</li>
<a name="wp1072981"> </a><p class="pBodyRelative">
<div>
<table border="2" cellpadding="2" id="wp1072934table1072931">
  <caption><a name="wp1072934"> </a><div class="pTableTitle">
Table&#160;23-3	Physically Removing the Cable for the SmartBits Scenario 

</div>
</caption>
  <tr bgcolor="#CCCCCC" align="left" valign="middle">    <th colspan="2" rowspan="1"><a name="wp1072942"> </a><p class="pCellHeading">
PortChannel Scenario 

</p>
</th>
    <th colspan="2" rowspan="1"><a name="wp1072946"> </a><p class="pCellHeading">
FSPF Scenario (Equal cost ISL)

</p>
</th>
</tr>
  <tr bgcolor="#CCCCCC" align="left" valign="middle">    <th><a name="wp1072950"> </a><p class="pCellHeading">
Switch 1

</p>
</th>
    <th><a name="wp1072952"> </a><p class="pCellHeading">
Switch 2

</p>
</th>
    <th><a name="wp1072954"> </a><p class="pCellHeading">
Switch 1

</p>
</th>
    <th><a name="wp1072956"> </a><p class="pCellHeading">
Switch 2

</p>
</th>
</tr>
  <tr align="left" valign="top">    <td colspan="2" rowspan="1"><a name="wp1072958"> </a><p class="pBody">
110 msec (~2K frame drops)

</p>
</td>
    <td colspan="2" rowspan="1"><a name="wp1072962"> </a><p class="pBody">
130+ msec (~4k frame drops)

</p>
</td>
</tr>
  <tr align="left" valign="top">    <td colspan="4" rowspan="2"><a name="wp1072966"> </a><p class="pBody">
100 msec (hold time when a signal loss is reported as mandated by the standard)

</p>
</td>
</tr>
  <tr align="left" valign="top"></tr>
</table>
</div>

</p>
<a name="wp1073025"> </a><p class="pBodyRelative">
<div>
<table border="2" cellpadding="2" id="wp1072985table1072982">
  <caption><a name="wp1072985"> </a><div class="pTableTitle">
Table&#160;23-4	Shutting Down the Switch for the SmartBits Scenario 

</div>
</caption>
  <tr bgcolor="#CCCCCC" align="left" valign="middle">    <th colspan="2" rowspan="1"><a name="wp1072993"> </a><p class="pCellHeading">
PortChannel Scenario

</p>
</th>
    <th colspan="2" rowspan="1"><a name="wp1072997"> </a><p class="pCellHeading">
FSPF Scenario (Equal cost ISL) 

</p>
</th>
</tr>
  <tr bgcolor="#CCCCCC" align="left" valign="middle">    <th><a name="wp1073001"> </a><p class="pCellHeading">
Switch 1

</p>
</th>
    <th><a name="wp1073003"> </a><p class="pCellHeading">
Switch 2

</p>
</th>
    <th><a name="wp1073005"> </a><p class="pCellHeading">
Switch 1

</p>
</th>
    <th><a name="wp1073007"> </a><p class="pCellHeading">
Switch 2 

</p>
</th>
</tr>
  <tr align="left" valign="top">    <td><a name="wp1073009"> </a><p class="pBody">
~0 msec (~8 frame 
drops)

</p>
</td>
    <td><a name="wp1073011"> </a><p class="pBody">
110 msec (~2K frame 
drops)

</p>
</td>
    <td colspan="2" rowspan="1"><a name="wp1073013"> </a><p class="pBody">
130+ msec (~4K frame drops) 

</p>
</td>
</tr>
  <tr align="left" valign="top">    <td><a name="wp1073017"> </a><p class="pBody">
No hold time needed 

</p>
</td>
    <td><a name="wp1073019"> </a><p class="pBody">
Signal loss on switch 1

</p>
</td>
    <td><a name="wp1073021"> </a><p class="pBody">
No hold time needed 

</p>
</td>
    <td><a name="wp1073024"> </a><p class="pBody">
Signal loss on switch 1 

</p>
</td>
</tr>
</table>
</div>

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

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