CUCM 8.6.2 Phones not registering 7841 and 8831

[#1]

Hi all

I am trying to register some new phones - 7841 and 8831.  We installed the COP and Device Pack and rebooted the cluster.  Firmware defaults in the server are sip78xx.10-1-1SR2-1 and sip8831.9-3-3-5. 

These are the first phones of these models that we are trying to use.  All other devices are up and working.  I added the phones manually, auto-reg is disabled.  These new phones are both displaying the same behavior - they booted, but neither device will register.  They are both running the the same firmware version configured as the default in the server.

I have looked at some other discussions but haven't seen any solutions that match up with our issue.   Your input and ideas appreciated, thanks

[MIKE DEDMON]

Ok, I tried this and no luck. Based on your suggestion, I changed the port to this configuration:

interface FastEthernet0/25
 description Workstations on VLAN2 - Phones on VLAN 100
 switchport access vlan 2
 switchport trunk encapsulation dot1q
 switchport mode access
 switchport voice vlan 100
 srr-queue bandwidth share 10 10 60 20
 srr-queue bandwidth shape 10 0 0 0
 mls qos trust device cisco-phone
 mls qos trust cos
 auto qos voip cisco-phone
 spanning-tree portfast

No difference. The 8831 still shows the exact same info. Same VLAN 100, Admin VLAN 4095, IP address on the DATA Vlan, and all the same error messages.

It's frustrating that all 200+ of my other phones, including the 7937 can connect. This is the only one I've seen behave like this.

[Dragan Ilic]

Where is DHCP located for phones?

You have option 150 on it?

BR,
Dragan

[MIKE DEDMON]

DHCP for VLAN 100 (voice) is served by the 3750 switch stack. We have a windows DHCP server for VLAN 2 (data). Both of them server up the TFTP server.

The 8831 is showing the correct TFTP server address as well.

[Dragan Ilic]

And other 200+ phones - they receive their IP from DHCP for VLAN 100 fine? 

Or you configured them manualy?

Something is strange there - there is no way that only one phone makes troubles and the rest are working fine in same VLAN with same DHCP etc???

Dragan

[MIKE DEDMON]

Yes - 18 locations, multiple routers/switches (all Cisco), same setup. All phones work fine, but this model of phone.

I'm truly stumped. What's strange is if I change all of the VLAN settings on the port to be VLAN 100 and I specify the allowed VLANs on the trunk as only 100, it still gets an IP from the DATA network.

... While typing this, I had a thought ...

--UPDATE: It's connected and working. I changed the settings on the phone from DHCP to STATIC and assigned it a VLAN 100 IP address from the phone system.

This is definitely not ideal. Plus, after heavily searching google, a LOT of people are having these same or very similar registration issues with this model of phone, and I wonder if there's a bug in the firmware that doesn't handle VLAN trunking or tagging correctly? How would I get this information to Cisco TAC to get them to look into it? Any suggestions?

[Dragan Ilic]

You can always search cisco bug toolkit on cisco.com if you have adequate privileges with your CCO account.

Other options - try to write to tac@cisco.com some unofficial mail and I think that some of support engineers is going to answer you even if you don't have any official contract with cisco.

BR,

Dragan

[Aman Soi]

Hi Mike,

Just  guessing 

7841 Cannot join VLAN if broadcast over 30kbps

CSCun23612

Description

Symptom:
7841 Devices are not able to process CDP response to gain VLAN knowledge from switch when large amount of broadcasts (30kbps / approx 40 to 60 pps) on VLAN/Subnet are occurring. 

The phone looks like it will still follow through with DHCP requests but will not accept the offered DHCP address due to the phone not knowing the VLAN structure.

** Issue does not occur when same amount of traffic is sent directly to the phone; only when it is broadcast traffic.

Conditions:
7841 on a switch port with a VLAN with a large amount of broadcasts occurring in subnet.

Workaround:
Reduce Broadcast traffic below 30kbps and reboot phone
or
Remove VLAN from Switch port that has the high Broadcast traffic.

[+5] to Dragan for extending support.

regds,

aman 

[tschmidt255]

I was experiencing the exact same issue as Mike.  I put the phone behind a router on it's own network.  It received an IP address for the voice VLAN and registered without any issues.

Tim

[Richard Simmons]

Hi Mike,

Did you get this resolved, i am having the same issue today, 7841's are getting IP address's from the data vlan when the switchport is configured as a trunk and not access.

Thanks, 

Richard

[MIKE DEDMON]

Hi,

Not in the manner I wanted, but I did find that setting a fixed IP from the voice VLAN on the phone made it work. Using DHCP was the problem. Still no permanent solution, but I don't have a lot of these and they move rarely. If I do move them, I just have to remember to change the static IP and to update the reservation in the DHCP server.

[Brian Meade]

I've seen issues with the 78XX phones not registering due to MTU issues.  I'd suggest a packet capture from CUCM and phone side.

I had to lower the MTU on my CUCM servers to get my 7861s to register.