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New Member

7940 phones unable to obtain IP address

Hi,

I'm currently entering the VoIP world and I've been having a hard time trying to get my phones to register with the CME/TFTP server on my network. The phones are 7940's and they will not obtain an ip address from the DHCP server and complete it's boot process (contact the tftp server and download its configuration files). I have a CIPC that was able to register without any issues. My DHCP router shows my 7940's requesting an IP address (show ip dhcp bindings) but the phones are stuck on "configuring IP". Any advice or leads as to what I should do next? PLEASE HELP!!!

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8 REPLIES

7940 phones unable to obtain IP address

Hi,

what is your CME version. did you enable CDP advertisment on the switch ?

HTH

Anas

please rate all helpful posts

New Member

Re: 7940 phones unable to obtain IP address

Anas,

Thanks for the quick response, I'm running CME 7.0. My IOS is 12.4(22)T5 on a 2811 router. Correct me if I'm wrong but arent CDP advertisements enabled by default? I haven't changed anything in regards to CDP.

Just some backround info in hopes of deciphering this issue.

VOICE network: 172.16.1.0/24 VLAN 10

DATA network: 172.16.2.0/24 VLAN 50

One of my 7940's has SIP on it according to the firmware load on the "STATUS" tab

The application load ID is P0S3-07-4-00

I have a 2811 that is running CME and is the TFTP server as well.

The TFTP server has all the necessary firmware files needed to for the IP phones to register with the CME

P00308000500.bin

P00308000500.loads

P00308000500.sb2

P00308000500.sbn

ip dhcp excluded-address 172.16.1.1 172.16.1.10

ip dhcp excluded-address 172.16.1.245 172.16.1.254

ip dhcp excluded-address 172.16.2.245 172.16.2.254

ip dhcp excluded-address 172.16.2.1 172.16.2.10

!

ip dhcp pool VOICE

   network 172.16.1.0 255.255.255.0

   default-router 172.16.1.1

   dns-server 4.2.2.2

   option 150 ip 172.16.1.1

!

ip dhcp pool DATA

   network 172.16.2.0 255.255.255.0

   default-router 172.16.2.1

   dns-server 4.2.2.2

   option 150 ip 172.16.1.1


Now I've had a few developments from the very first post. When I assign a static IP address to the phone that has SIP, it says on the screen the screen TFTP P00308000500.loads after a reboot. It thensays "Phone unprovisioned" Is it trying to locate the TFTP server or did it and it can't find the correct files to load for it to complete its registration process? Would you like to see my configs by chance?

Leo,

Yes I programmed option 150 in my DHCP scope. Just as a heads up my DHCP server is a 3745 router with an IP address of 172.16.2.5/24 on Fa0/0

These are my DHCP settings

ip dhcp excluded-address 172.16.1.1 172.16.1.10
ip dhcp excluded-address 172.16.1.245 172.16.1.254
ip dhcp excluded-address 172.16.2.245 172.16.2.254
ip dhcp excluded-address 172.16.2.1 172.16.2.10
!
ip dhcp pool VOICE
   network 172.16.1.0 255.255.255.0
   default-router 172.16.1.1
   dns-server 4.2.2.2
   option 150 ip 172.16.1.1
!
ip dhcp pool DATA
   network 172.16.2.0 255.255.255.0
   default-router 172.16.2.1
   dns-server 4.2.2.2
   option 150 ip 172.16.1.1

Additionally, my DHCP router is connected to Fa0/10 on a 3550 switch (SwitchA). Fa0/10 on the SwitchA has been set as an access port on vlan 50. Fa0/24 is connected to a second 3550 switch (SwitchB) on port Fa0/24 with a trunk connection. SwitchA has port Fa0/20 configured as a trunk port and it goes to the CME/TFTP router.

William,

That is a good question. I tried pinging the CME router from my DHCP router and was successful in pinging the data subinterface but I was unable to ping the Voice subinterface. Isn't that a good thing though based on the fact that the Voice and Data networks should not be able to reach other? I also noticed that my laptop was unable to obtain an IP address as well nor did the DHCP server show it offering a IP address. Is there a misconfiguration in my DHCP router perhaps? What do you advise should be next step? I've attached the configs to all 4 of my devices and did a "show CDP neighbors" on all of them as well.

Thanks in advance to all who are willing to help! Please continue with the feedback...

JM

Hall of Fame Super Gold

7940 phones unable to obtain IP address

My DHCP router shows my 7940's requesting an IP address (show ip dhcp bindings) but the phones are stuck on "configuring IP".

Did you configure Option 150 in your DHCP scope?

New Member

Re: 7940 phones unable to obtain IP address

Leo,

Yes I programmed option 150 in my DHCP scope. Just as a heads up my DHCP server is a 3745 router with an IP address of 172.16.2.5/24 on Fa0/0

These are my DHCP settings

ip dhcp excluded-address 172.16.1.1 172.16.1.10
ip dhcp excluded-address 172.16.1.245 172.16.1.254
ip dhcp excluded-address 172.16.2.245 172.16.2.254
ip dhcp excluded-address 172.16.2.1 172.16.2.10
!
ip dhcp pool VOICE
   network 172.16.1.0 255.255.255.0
   default-router 172.16.1.1
   dns-server 4.2.2.2
   option 150 ip 172.16.1.1
!
ip dhcp pool DATA
   network 172.16.2.0 255.255.255.0
   default-router 172.16.2.1
   dns-server 4.2.2.2
   option 150 ip 172.16.1.1

Additionally, my DHCP router is connected to Fa0/10 on a 3550 switch (SwitchA). Fa0/10 on the SwitchA has been set as an access port on vlan 50. Fa0/24 is connected to a second 3550 switch (SwitchB) on port Fa0/24 with a trunk connection. SwitchA has port Fa0/20 configured as a trunk port and it goes to the CME/TFTP router.

Thanks for helping, any other suggestions? My config files are attached above.

Cisco Employee

7940 phones unable to obtain IP address

Hi,

Have you checked if the switchports have access to the data and the voice vlans?

Regards.

New Member

Re: 7940 phones unable to obtain IP address

William,

That is a good question. I tried pinging the CME router from my DHCP router and was successful in pinging the data subinterface but I was unable to ping the Voice subinterface. Isn't that a good thing though based on the fact that the Voice and Data networks should not be able to reach other? I also noticed that my laptop was unable to obtain an IP address as well nor did the DHCP server show it offering a IP address. Is there a misconfiguration in my DHCP router perhaps? What do you advise should be the next step? I've attached the configs to all 4 of my devices and did a "show CDP neighbors" on all of them as well. Attachments are above.

Thanks in advance to all who are willing to help! Please continue with the feedback...

JM

Cisco Employee

Re: 7940 phones unable to obtain IP address

Jason,

Try adding both vlans to the switchport and let me know how it works.

Regards.

New Member

Re: 7940 phones unable to obtain IP address

Both vlans 10 (voice) and 50 (access) are associated with switchports 3 & 4 which are connected to my 7940 phones as shown on the "Switch B" text config file above. Both switchports have always had this configuration. Thanks for the quick response, any other suggestions?

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