Basic Failover Questions - Cisco Catalyst 6500 Series Configuration Manual

Chapter 15 Using Failover
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Basic Failover Questions

See the following questions and answers for basic failover:
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OL-6392-01
What happens if the configuration in Flash memory on the secondary module differs from the
configuration on the primary module?
After startup, the primary module sends its configuration to the secondary module and erases the
running configuration on the secondary module. However, the secondary module startup
configuration remains unaltered in Flash memory.
How can I view the running configuration and the Flash memory configuration?
– show running—Shows the running configuration. You can also enter write terminal.
show config—Shows the configuration in Flash memory.
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Are contexts that are on disk saved to disk on the standby module?
No, all contexts are loaded into running memory only. The startup configuration for a context
continues to reside on the primary module disk. You can copy the context configurations to the
standby module so that if the standby module starts up and needs to be the active module, it can load
the contexts from disk.
Can I fail over a context, but not the entire module?
No, you can only have one active FWSM.
Which module becomes active if you restart both modules?
The primary module.
What happens if the active module has a power failure?
After hello messages are not acknowledged, the standby module becomes active.
What happens when the formerly active module comes online again?
No failover occurs. It remains in standby mode.
How long does it take to detect a failure?
Network errors are detected within three consecutive polling intervals (by default, 15 second
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intervals). The polling interval is user-configurable using the failover poll interface command.
Failover communication errors are detected within a user-configurable number of seconds (the
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default is 15). The polling time is user-configurable using the failover poll unit command.
What maintenance is required?
Syslog messages are generated when any errors or switches occur. Evaluate the failed module and
fix or replace it.
Is it possible to have both FWSM modules become active at the same time?
Yes, in the following circumstances:
Both modules have configurations in Flash memory
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– Both modules have failover enabled
– The failover link is down at startup
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Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide
Frequently Asked Failover Questions
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