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New Member

Cisco 7940/60 DHCP problem (configuring IP)

Hi all,

i have some problem with my cisco 7940/60 cisco 7940/60 with 8.1(2) firmware would not register to CM 8.6(2)SU3. the problem was the phone is configuring IP and get DHCP server is i tried to upgrade firmware to be 8.1(2)_SR2 and the problem solved. Cisco 7940/60 can register with CM.

Now the problem is reapper. when the 7940/60 phone resetted, the phone is configuring IP and get DHCP server i have checked network and DHCP issue but no problem in there. and when i redowngrade the firmware to 8.1(2) ip phone get their ip address and registered well.

what should i to solve this problem when the problem reappear? is it BUG?

kindly thanks,

Hall of Fame Super Silver

Re: Cisco 7940/60 DHCP problem

I've never heard of similar bug, I would focus on looking at your network and try to sniff what is being received on the phone when dhcp is requested, perhaps thee us a rogue one on the network.


Sent from Cisco Technical Support iPhone App

New Member

Re: Cisco 7940/60 DHCP problem

Hi Chris,

Sorry for late reply,


it's happen (unfortunate configuring IP) only on 7940/60. all types except 7940/60 such as 7945 & 7975 working well.

i have gathered the log file from wireshark (as attached) and get error message :

source(TFTP) dest(IP Phone) === Data Packet , Block: 13 (last)

source(IP Phone) dest(TFTP) === Acknowledgment, Block: 13

source(IP Phone) dest(TFTP) === Read Request, File:CTLSEP(MAC).tlv, transfer type: octet

source(TFTP) dest(IP Phone) === Error code, code : file not found, message : file not found

would you like help me to read the logs?

my TFTP address :

my IP Phone address :