Callmanager TFTP on another Subnet Problem Irritating

[avang2004]

We are having problems with Cisco phones 7940,7960, 7970's registering in the 192.168.6.0 subnet it's our voice subnet VLAN 17, usually it registers in the 192.168.5.0 subnet VLAN 9 our Data subnet. We think it has to do with the TFTP server being in the 172.16.16.0 subnet VLAN 17. When you assign the cisco 7960 phone a static address from the 192.168.6.0 pool, specify the default router 1 192.168.6.1, tftp server 1 172.16.16.3 then it registers to the CCM ok.

[avang2004]

the 192.168.6.0 pool does have the tftp option assigned to 172.16.16.3

[clsalaza]

I believe the problem is the default router that dhcp is injecting, but not sure. Would it be possible for you to get an sniffer between the phone and the switch to look further?

[agopala]

Can you please remove the following line from the config?

switchport mode dynamic desirable

I assume this is not a switchport module. This is a 3550 or an xl switch.

That should do the trick. It does not matter where your TFTP server is, because it goes in search of the TFTP server after DHCP is complete.

[andrewsmith]

This seems similar to my problem.

See:- 7940 gets incorrect dhcp address

Regards

Andy

[kkrake]

I have been having the same problem with brand new phones from the factory. It seems that if you hard code a phone for the first pass and then it upgrades its software that this goes away. Any one else seen this?

[michael_davis]

I too have seen this. I've observed this in 7936, 7940, 7960, while first connecting to 3550, 3750, and 6500 switches.

I've found that if I first connect to an access-mode switch port where the access vlan is my voice vlan, the phone gets it's upgrade then works fine. Guess that's the same as you are doing, but perhaps a little quicker to configure, I think.

Seems the whole CDP/voice vlan identification mechanism is broken in some, but not all factory loads.