cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
645
Views
0
Helpful
13
Replies

phones lost connection

Austin3:16
Level 1
Level 1

I've noticed that some IP phones, specifically the 3905 model, enter "configuring IP" mode. Upon diagnosing the issue, I observed that these IP phones lose their IP addresses from the DHCP server. Even when configured in static mode, the problem is temporarily resolved, but after a few days, the phones lose their IP addresses again. The phone in static mode also becomes unpingable. I performed an upgrade to the latest version, but the issue persists after a few days.

and I noticed some port instability on the switch.

1 Accepted Solution

Accepted Solutions

Hi,

I noticed this behavior in the past but it was not a DHCP issue. It was a bug with CDP messages received by the phone that was interpreted as port reconfiguration message.

Try to statically define the Voice Vlan on the phone and disable CDP on the switch interface.

Please let me know 

 

Regards

 

Carlo

Please rate all helpful posts "The more you help the more you learn"

View solution in original post

13 Replies 13

Leo Laohoo
Hall of Fame
Hall of Fame

@Austin3:16 wrote:
but after a few days, the phones lose their IP addresses again.

How long is the DHCP lease?


@Leo Laohoo wrote:

@Austin3:16 wrote:
but after a few days, the phones lose their IP addresses again.

How long is the DHCP lease?


8 days but the problem with static ip too


@Austin3:16 wrote:
8 days but the problem with static ip too

Can you elaborate the meaning of "static IP"?  Did you manually assign an IP address to the phone or did you put a MAC address reservation against an IP address? 

Bring the lease down to 8 hours and see if it makes a difference.

You note switch port instability. I can see that impacting the phones. I assume you are taking steps to diagnose and resolve that issue.

Do the phones come back if you power-cycle the port?

Maren

yes

Hi,

I noticed this behavior in the past but it was not a DHCP issue. It was a bug with CDP messages received by the phone that was interpreted as port reconfiguration message.

Try to statically define the Voice Vlan on the phone and disable CDP on the switch interface.

Please let me know 

 

Regards

 

Carlo

Please rate all helpful posts "The more you help the more you learn"

Ok i will let you know if the problem percist.

I have concerns about the Switches 2960  can upgrading the firmware resolve the issue since they have an old firmware 

yes you are right and its solve my problem 

It depends on what model of 2960 you have.

Some of them went in EoL ages ago and firmware is no longer available on Cisco Software Manager.

 

Let me know 

 

Thanks

Carlo

Please rate all helpful posts "The more you help the more you learn"

Yes know, they have E6 firmware i will try to E9 its the last version

before upgrading the firmware, please try what I suggested to verify if the issue solves with this configuration 

 

Thanks

 

Carlo

Please rate all helpful posts "The more you help the more you learn"

 If I disable CDP, will there be any impact on Cisco access points?

Technically it doesn’t have any impact on AP but you don’t need to disable it globally but on single interface where 3905 are connected to.

 

Let me know 

 

Cheers

 

Carlo

Please rate all helpful posts "The more you help the more you learn"
Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: