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New Member

Malformed TFTP packets from 7960 IP Phone

I've got a Cisco 7960 IP Phone (firmware version at present: 3.1) on my network that is configured to use my desktop machine as a TFTP server.

The phone connects to the DHCP server fine, and is visible on the network. The phone tries to connect to the TFTP server and request the files. The TFTP server that I'm using (the solarwinds one for windows) logs the request for each file requested, but returns a timeout error without transferring the file. The phone gives the same error.

After monitoring the packets with Ethereal, I've found that the TFTP packets sent from the 7960 are malformed.

Does anyone have any advice that would help me get this working?

5 REPLIES

Re: Malformed TFTP packets from 7960 IP Phone

Hi,

in case the TFTP packets are malformed there is nothing you can do about, but to upgrade the 7960 firmware.

There is no configuration command to create "malformed" packets, so you found a software bug.

Hope this helps

Martin

P.S.: Out of curiosity: what is "malformed" about the TFTP packets?

New Member

Re: Malformed TFTP packets from 7960 IP Phone

Thanks for your reply,

I've looked at the packets in a little more detail, and it appears that there is no checksum being sent.

Could this be corrected by me finding or writing a software firewall to correct this (even though it defeats the purpose of the checksum)?

As far as I know, the only way to upgrade the 7960's firmware is via TFTP. Is there another way (besides opening it up and writing to the flash chip directly)?

Thank you.

Tim.

Re: Malformed TFTP packets from 7960 IP Phone

Hi,

have you tried another TFTP server? There are plenty of freeware TFTP servers and it might be possible with one of them.

Also have a look at

"Cisco 7940 and 7960 IP Phones Firmware Upgrade Matrix"

http://www.cisco.com/en/US/products/sw/voicesw/ps4967/products_upgrade_guides09186a008022a968.html

Regards

Martin

New Member

Re: Malformed TFTP packets from 7960 IP Phone

I have the same problem! TFTP server can not be a reson of malformed packets from 7960-phone! But i've tryed a lot of tftp-servers, and problem hasn't decided! I have not any idea about reason of this serious problem!

Hall of Fame Super Gold

Re: Malformed TFTP packets from 7960 IP Phone

timsheridan wrote:

Thanks for your reply,

I've looked at the packets in a little more detail, and it appears that there is no checksum being sent.

Which checksum are you referring to?

TFTP uses UDP, and checksum on UDP is optional. Consequently, TFTP packets sourced from phone are perfectly valid.

As far as I know, the only way to upgrade the 7960's firmware is via TFTP. Is there another way (besides opening it up and writing to the flash chip directly)?

There is no other way.

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