Alternate TFTP using DHCP

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Nov 18th, 2008
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I would like to enable the alternate TFTP server option for the phones part of Communication Manager 6.1 cluster.

Can I configure this option for all phones using a DHCP server? I already have configured the Option 150 (for the Pub IP) in my DHCP server

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Overall Rating: 4 (2 ratings)
Rob Huffman Tue, 11/18/2008 - 10:18
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Hi Amith,

Here is a related clip;

In the simplest configuration, where a single TFTP server is offering service to all deployed endpoints,

Option 150 is delivered as a single IP address pointing to the system's designated TFTP server. The

DHCP scope can also deliver two IP addresses under Option 150, for deployments where there are two

TFTP servers within the same cluster. The phone would use the second address if it fails to contact the

primary TFTP server, thus providing redundancy. To achieve both redundancy and load sharing between

the TFTP servers, you can configure Option 150 to provide the two TFTP server addresses in reverse

order for half of the DHCP scopes.

Note If the primary TFTP server is available but is not able to grant the requested file to the phone (for

example, because the requesting phone is not configured on that cluster), the phone will not attempt to

contact the secondary TFTP server.

Cisco highly recommends using a direct IP address (that is, not relying on a DNS service) for Option 150

because doing so eliminates dependencies on DNS service availability during the phone boot-up and

registration process.

From this excellent SRND Guide;

Hope this helps!


amith.kumar Tue, 11/18/2008 - 10:34
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Hello Rob,

Thanks for the detailed information. Would this be applicable for Communication manager 6.1 as well?



amith.kumar Tue, 11/18/2008 - 10:46
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Great thanks again.

Would also like to know what is the significance of using domain name in IP Phones?

We have setup DNS (windows 2003 server) for EM redundancy and phones query the DNS for IP addresses of all servers in order. Would there be a need to configure the call manager domain name from the CLI (using set network domain name command?) and also the domain name using DHCP scope options for the IP Phones?


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