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Callmanager TFTP Failover

Has anyone had success on redundant callmanagers where if the primary fails (which has the tftp server), the ip phones will still stay up without attempting to re-register? So far, testing has been unsuccessful. Once the primary/tftp callmanager fails, the ip phones try to register but are unable find their settings. Any ideas would be helpful.




Re: Callmanager TFTP Failover

I wish Cisco wouldn't advertise them as 'primary' and 'backup'. That's not really the case as you've noticed. I've found I can have the publisher down for short periods, but if a phone reloads, it won't come up do to the missing dhcp/tftp services. Some of the features, such as services and directories are also pointing only in one place. You might want to check that the dhcp lease times are adequately long as well.

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Re: Callmanager TFTP Failover

Yeah, this doesn't really work as advertised; it's not really primary and secondary tftp servers. If the primary goes down, there's no facility for a secondary TFTP server to kick in.

However, this only comes into play when phones reboot and look for the TFTP server. If the phone has been registered before and cannot find the TFTP server it is supposed to use the cached configuration that is in memory. This doesn't always seem to work.

Depending on the size of your deployment, you could add a dedicated TFTP server. We have 1 publisher (doesn't handle calls), 3 Subscribers (Primary, secondary, and tertiary), 1 TFTP/WWW Server, and 1 MOH Server.

Half of my phones are registered to the Primary Subscriber, and the other half are subscribed to the secondary subsriber. The third subscriber is hot backup incase one of the other subscribers fails. All phones point to the TFTP server for TFTP. The TFTP server also handles all WWW services for the cluster (ccmadmin, ccmuser, ip phone services, etc.)

Tim Medley, CCNP+Voice, CCDP, CWNA

Sr. Network Architect

VoIP Group


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