Phones Not Receiving DHCP IP

[bergquist]

Hello Experts -

We recently replaced our Call Manager servers, jumping from 4.1 to 7.1 after successfully running DMA backup/restore.

Most everything is working fine except when I've had to add a new ip phone to our system. The problem is that it cannot receive a DHCP ip address from the server.

I've checked all the settings that I can possibly find and everything looks like it is configured correctly. If I manually assign an ip to a phone (we are using mostly 7940's and 7960's), then the phone will boot and register fine and works like it should after flashing its image and getting the correct load and firmware.

Rebooting an existing phone in our environment (phones that were online when we had CM 4.1) will boot up more slowly, but it will finish and come online, so apparently it is caching that info from before.

The problem is with a new phone and the only way for me to get it to work is to manually assign the ip. No other changes were made to our environment, so I don't think it would be useful to try to capture any switch packets. I'm wondering if there is something I've missed with our DHCP setup.

Any advice would be appreciated. My TAC engineer basically gave up on me :-(

[bergquist]

I believe these are the ones.

[Aaron Harrison]

Hi

I meant the packet cap from the server.

The tftp logs will only be of use once the basic IP config is set on the phone, so that's a step too far ahead.

Cheers

Aaron

[bergquist]

Ah, wrong folder. Sorry.

[Aaron Harrison]

Hi

So that packet 7709 that you listed - this appears to be a phone on the local server subnet, as there is no DHCP relay agent information associated with it (this would be an IP associated with whatever device is configured with ip helper-address)

Either that - or your phone isn't in the VLAN you think it is. I see repeated DHCP Discovers from this phone, so if you create a DHCP scope on the server for the subnet that the CCM is in, you should see it pick up an address.

Can you confirm the MAC address of a problem phone?

Thanks

[Aaron Harrison]

In fact, scratch that - it's 2230 here, getting sloppy...

So your phones and server are on the same VLAN, it's a class B.

Can you verify that your server has the correct subnet mask? That's the only thing that springs to mind that would prevent the scope that you screen grabbed from handing out an address in response to a local broadcast. If that's not right, server would not see the interface that receives the request as being in the subnet related to that scope.

Regards

Aaron

[bergquist]

The only thing that looks funny to me (I did not do the config on this upgrade, might have been helpfull...) is the subnet mask has 255.255.000.000, instead of 255.255.0.0. but it does have that under the network>ip settings. Not totally familiar with the management gui yet. We went from 4.1 (Windows) to 7.1, but successfully ran a DMA backup/restore, or so I'm told.

When I first became of aware of this issue and it became my problem, DHCP was not even configured...but even after configuring it (and restarting the service) it still have not worked. We have not restarted that actaully Call Manager service or the servers themselves yet and I would think that would not be necessary.

We also are not using DNS, but we were not using it on our last CM's either.

[tholemu84]

  What model phone is it and did the phone go through any sort of upgrade hen you connected it?  What version of firmware is that phone running compared to the other ones?

-Matt Bowler

[bergquist]

We're using 7940's and 60's and getting the issue on both.

The firmware upgrades to the current version 8.1 (1.0) when I manually assign an ip to a phone so that it can register with CUCM. But then when I configure the phone back to DHCP, it still goes back to the same issue and hangs on configuring IP.

I was also thinking that there could be some kind of firmware mismatch with the older phones and a newer CUCM, but I've not found anything that says that nor did Cisco TAC mention it.

[tholemu84]

  I know that some of the phones I tested were unable to recieve IP's, or it appeared so.  Sounds too simple, but have you tried going to the erase configuration option, selecting 'yes' and letting it reset?  I don't understand exactly what the problem could be if it is able to retrieve firmware upgrade.  This would appear to tell me that the MAC was entered correctly and your DHCP is working to some extent.  What are you using to direct the TFTP address to the phone?  For testing purposes, we don't use the DHCP server on the actual CME server, but rather use DHCP built into the router with an 'option 150.'

  When you open the status messages under settings on the phone is there anything out of the ordinary showing up?

-Matt Bowler

[bergquist]

Yes that was one of the first things we tried which didn't help.

The reason its getting the firmware upgrade is I manually give the phone a static ip, at which point it can then register correctly with the server and get the correct load config and firmware (or it does that before registering). It works fine with static, so at the very least, I can still swap out a broken phone if need be.

Someone else mentioned about using DHCP with our gateway router, but I'm not familiar with that config setup.

After the phone has successfully registered, I see the SEP(MAC)cnf.xml file listed. There is nothing listed in Status when the phone is in it's stuck, "Configuring IP" state.

[paolo bevilacqua]

It can also be an issue with switch firmare (CDP things).

So for example downgrading to 8.0(10) would be a safe choice.

[tholemu84]

Manually setting up a DHCP server on a router requires a few steps..

  -Setup IP Address Exclude List

ip dhcp excluded-address

  -Create DHCP Pool

ip dhcp pool

   network
   default-router
   dns-server
   option 150 ip