CCNP TSHOOT 6.0 - Cisco Learning Home
CCNP TSHOOT 6.0 - Cisco Learning Home
CCNP TSHOOT 6.0 - Cisco Learning Home
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<strong>CCNP</strong>v6 <strong>TSHOOT</strong><br />
Sample First Hop Redundancy<br />
Troubleshooting Flow<br />
Determine if<br />
outages are<br />
caused by<br />
FHRP or<br />
other<br />
protocols<br />
Determine if<br />
FHRP<br />
addresses<br />
are used by<br />
hosts<br />
Verify Layer 3<br />
connectivity<br />
between routers<br />
Investigate<br />
FHRP<br />
router-toroutercommunication<br />
Investigate<br />
FHRP role<br />
selection<br />
Verify reception of<br />
FHRP messages<br />
© 2009 <strong>Cisco</strong> Systems, Inc. All rights reserved. <strong>TSHOOT</strong> v1.0—41<br />
Many problems with FHRPs are caused by underlying problems in the Layer 3 connectivity between the routers.<br />
Therefore, a good next-step in the troubleshooting process is to verify that there is Layer 3 connectivity between<br />
all routers that are participating in the FHRP. Ping from each of the participating routers to the IP addresses of the<br />
other participating routers. If one of these pings fail, start a troubleshooting process to diagnose and resolve the<br />
Layer 3 connectivity issues between the routers before further investigating the FHRP.<br />
When you have confirmed that there is Layer 3 connectivity between the participating routers in general, you must<br />
verify the proper transmission and reception of FHRP packets. To limit potential disruption, always use show<br />
commands to gather information before using debug commands.<br />
Verify Reception of FHRP Messages<br />
DLS1#show standby vlan 100 brief<br />
P indicates configured to preempt.<br />
|<br />
Interface Grp Pri P State Active Standby Virtual IP<br />
Vl100 100 110 P Active local 10.1.100.253 10.1.100.254<br />
DLS2#show standby vlan 100 brief<br />
P indicates configured to preempt.<br />
|<br />
Interface Grp Pri P State Active Standby Virtual IP<br />
Vl100 100 100 P Standby 10.1.100.252 local 10.1.100.254<br />
This example shows how to confirm proper transmission and reception of HSRP messages. For GLBP or VRRP,<br />
the procedure is similar, although the command output is slightly different.<br />
To confirm the proper reception of HSRP messages on all routers in the group, verify that all routers list an active<br />
and a standby router and that these roles are listed in a consistent way across all the routers. The show<br />
standby brief command is concise and still shows the most relevant information. As you can see in the<br />
example, switch DLS2 lists the IP address of switch DLS1 as the active router. As the standby router, it lists<br />
“local” to indicate that it considers itself to be the standby router. On switch DLS1, the situation is the opposite:<br />
The address of switch DLS2 is listed as the standby address, while the active router is listed as local. While you<br />
are verifying these roles, this is also a good opportunity to confirm that both the standby group number and the<br />
All contents are Copyright © 1992–2010 <strong>Cisco</strong> Systems, Inc. All rights reserved. This document is <strong>Cisco</strong> Public Information. Page 22 of 26
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