Option 150 is not working. weired!

[Turbo727]

Hi All,

I am having a very weired issue when I configure CUCM 8.03 for one of our client. I have everything configured, CUCM, CUE and VG. all tested and working fine.

But when I configure dhcp on the core switch for one branch office, I got very strange issue. the cisco IP phones, 6921 and 7942, are able to get IP from the core switch, I can ping without any problem. but phones cant register with CUCM, which physically located at another office.

When I check the phone settings, I found the tftp server is blank. no matter where I configure the DHCP, the phone just cant get the TFTP ip address.

ip dhcp pool voip

netw 10.129.7.0 /24

defaut 10.129.7.1

option 150 ip 10.129.37.2

Can anyone please shed some light on this. thanks.

[Turbo727]

Just to make it clear, I said core switch, I meant the branch's core switch.

[Anthony Holloway]

Make sure the phones are set for DHCP, and Alternate TFTP is set to No.

Also, you can throw your PC into the VLAN, and capture with wireshark to see if the switch is giving out option 150.

[Grayson Wells]

I don't know if it will help, but I had a problem with the phones not updating to the correct TFTP server. I did a factory reset and it worked just fine.

[clileikis]

Are these SIP or SCCP based phones?

[Turbo727]

Thanks all.

it's SCCP. I didn't try factory reset because these phones were brand new out of boxs.

I also tried to move the dhcp server to the router, it didn't work.

[Turbo727]

I found the issue could be tftp timeout because of the high latency wan link.

Is there a way to set up a local tftp server for phone file downloading?

[Volodymyr Morskyy]

You can specify several IPs under 150 option. So in case of primary TFTP is unreachable phone will try secondary one. And yes, you can use local TFTP.

[Grayson Wells]

If the WAN link is poor enough to cause a TFTP timeout you may need to ask yourself if it is good enough to even make calls over. Is it worse than 150ms delay with 1% loss?

[clileikis]

You can purchase another subscriber server with the tftp service running on it for phones at the remote site and it can serve the tftp configuration files for your phones.