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Phone refuses to take TFTP IP address from DHCP server

Im stuck! I have 50+ phones in this building and not one of them will take the TFTP server IP address from any DHCP server. I've tried Win2K's DHCP server with option 150 and 66, NO LUCK. I've tried the IOS DHCP server in my 3640, both options 66 and 150, NO LUCK.

Since I've been writing this, I've tried to change the default router statement in the DHCP pool configuration (I changed it to 10.20.1.2 from 10.20.1.1), and now it works. That is the phone took the TFTP ip address, but now my default-gateway is incorrect :(

So to recap:

With the following configuration my phone says that its TFTP server is at 10.20.1.2. Not the 10.120.1.6 like I need it to be. By the way the DHCP server is sitting on 10.20.1.1. I guess that's where it's getting the 10.20.1.2 address?

ip dhcp excluded-address 10.20.0.1 10.20.1.49

ip dhcp pool IPphones

network 10.20.0.0 255.255.0.0

default-router 10.20.1.1

dns-server 10.3.2.1 10.3.1.2

domain-name worksourcefl.com

option 150 ip 10.120.1.6

lease infinite

With this configuration the phone takes the correct TFTP server IP address. The only difference is the default router is pointing to some none existing IP address.

ip dhcp excluded-address 10.20.0.1 10.20.1.49

ip dhcp pool IPphones

network 10.20.0.0 255.255.0.0

default-router 10.20.1.2

dns-server 10.3.2.1 10.3.1.2

domain-name worksourcefl.com

option 150 ip 10.120.1.6

lease infinite

I've also found out the phone's will take the correct TFTP server IP address if I dont put any default-router entry in the pool configuration.

The phones are running App Load P00303020700

with a boot load of PC03A300. Their almost 3 years old!

Any clues?

2 REPLIES
Bronze

Re: Phone refuses to take TFTP IP address from DHCP server

I would certainly start with the phone load, if that doesn't work, then update the IOS on the router. Again, if that doesn't work, you will probably have to sniff the traffic and see what's going on.

Rick

Re: Phone refuses to take TFTP IP address from DHCP server

Hi,

I had exactly the same problem - DHCP settings looked fine - but the phones had always the wrong tftp server in their configs.

In our case it was the DNS which was not properly configured.

Check your DNS servers and look if they have some wrong setting/alias which contain the wrong tftp IP address.

If you don't have the default-router entry in your DHCP setting, I guess the phones don't find the DNS anymore and this solved temporarly your problem.

Hope this helps,

Martin

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