7940 TFTP Problem

Unanswered Question


I have a large range of phones (7905's, 06's, 12's, 40's, 60' etc). The problem I have is that all the new 7940's get the wrong TFTP server and the wrong Call Manager IP address - all other new phone types are fine! I have only one tftp server, and one dhcp server (on the same box). All the other settings issued from DHCP on the 7940's are correct (except for TFTP/CCM). I have DHCP options 66 and 150 configured on my TFTP server.

Version of CCM is 4.1(3)sr4d.



I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
basit.malik Wed, 02/07/2007 - 01:32

I believe , you should only use option 150 for TFTP then try to restart yours DHCP Server. Hope it works !


mheusinger Wed, 02/07/2007 - 05:56


which IP is received in the 7940? Where does the wrong IP arise from?

You could also use a packet analyzer to get the DHCP packets and identify the field with the wrong IP and adjust your DHCP server accordingly.

Another possible reason could be a rogue DHCP server in your network.

Regards, Martin

Hi Martin,

The client (phone)IP address is correct (as allocated by the DHCP server). The 'wrong' address is the TFTP server address that DHCP assigns to the phone - all the other addresses are fine. All other phones except for 7940's get all the right IP addresses etc from the same DHCP server within the same network - it looks as though I have a problem with 7940's specifically. There are no other DHCP servers within my network.



John Burnham Tue, 03/06/2007 - 08:24

Have you tried looking to see if the IP address is manually entered on the 7940 phones? If not could you set-up a test in a lab environment were you set your dhcp pool for some arbitrary settings and see if the phone changes to that. You would need connection from you test environment to the CCM.

According to Cisco you should never user option 66 and option 150 at the same time.

Are you using a Network Registrar or the local router for DHCP information? I use the local router to supply a DHCP address to the phones at the local site. Below is an example of how I serve out the DHCP information to the phones.

ip dhcp excluded-address

ip dhcp pool VoIP_Phones



domain-name mycompany.com

option 150 ip

lease 3

I hope this helps.


This Discussion