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Cisco IP Phone 6921 keep displaying "IP Address Released"...

Dear All,


We are suffering with a strange issue...


Our office having multiple branches and all the branches connected to Data Center.


CUCM hosted in Data center... and SCCP 6921 & SIP 8971 phones are deployed in all the branches...

One branch office facing the fallowing strange issues...

The full voice setup was stable for 1 year... the issues started suddenly...

1. All the Cisco 6921 IP Phones keep displaying "IP Address released" for every 5 minutes... and phone gets disconnected (not restart) for sometime and gets new IP from DHCP... after 5 minutes above cycle occurs again...

2. Phones connected to HP Switches with Data VLAN is 52 & Voice VLAN is 70, and 6921 phones are jumping between the VLANs and phones getting IP from both data & voice vlan even though voice vlan is tagged through LLDP.

Please let me know what could be the reason for this issue and share with me your suggestions...

I have tried fallowing solutions... but no luck.

3. Upgraded the HP switch firmware...

4. SCCP 6921 latest firmware upgrade... 

5.. Other branches with same setup is very stable.

6. All the PCs connected through phones are equipped with Antivirus & up-to-date signature and systems are fully scanned.

I am expecting your kind suggestions and solutions... Thanks.






Cisco Employee

The best start to

The best start to troubleshoot this problem i believe is to take packet captures on the phone by turning on span to PC or to span to siwtch port where the phone is connected. We need to see what's going on in the network while this problem occurs.

Have you also  checked the lease times on the switch for the phones?

DO you have other phones connected to the same switch using dhcp? How do they behave?


Hi, In addition to what



In addition to what Sreekanth has said,you can have loog into bug

6921 SCCP: LLDP Neighbor IP Address is not correct
1. From a browser access: http://phone_IPv4_address/
2. Click on Network Statistics -> Network
3. Phone's lldp neighbor is a switch which has an ipv4 address
4. The LLDP Neighbor IP Address is not correct.



Community Member

Hi Aman...Thanks for the

Hi Aman...

Thanks for the response... you response gives me some hope...

The LLDP IP is strange in all the 6921 phones as mentioned below...

Other branches 6921 phones shows proper IP of the switch...

I already tried the different version of firmware upgrade in the phones, but no luck.

all access switches are upgraded except core switch which having SVIs for all the vlans.

So, let us try the HP core switch. Meantime is there any work around for this bug...?


LLDP Neighbor Device ID  GFU8-Access-SW02
LLDP Neighbor IP Address  


Community Member

Hi Sreekanth... thanks for

Hi Sreekanth... thanks for the response...


I tried the wireshark capture... as per the capture logs... phone is connected with DHCP IP... suddenly the phone sending the "dhcp request" to DHCP server... ack & reply happening and the phone gets new IP... all happening for no reason... otherthan above, no other useful information through wireshark...


Window 2008 R2 server serving as DHCP server for all branches... all branches getting proper DHCP service except the problematic site, so i have no doubt on DHCP server... and i tried the infinite, hours, days, weeks of lease duration, but no luck.


And i have 8961, 9971 phones in the same switches and they are working fine. Only 6921 phones got affected.


Community Member

Hi aman... Access switches

Hi aman... Access switches doesnt have IP address, thats why the MAC of the switch reflected as neighbour IP
Community Member

Hi Did you manage to resolve



Did you manage to resolve this issue, if yes please share how you resolved it. I am having the same issue with one of my client and not sure how to resolve it...


Your resolve is highly appreciated. thanks.

Cisco Employee

Did you take a look at the

Did you take a look at the status messages on the phone/? Do you see anything significant there? Does it say that the IP address was released?

What is the dhcp lease timing?

In all of the cases with this kind of issue, it's been changes on the hp switch that have solved the problem. Please check if the phone is getting the IP address every time from the same subnet. Also, you can try increasing the lease to infinite and see if that changes the behavior of the phone.

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