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New Contributor II

Ethernet Connection Lost

I have 15 IP phones directly connected to a Netvanta 1234P switch.  The switch is also providing POE to all the phones.  The phones are setup on a separate VLAN.  Periodically (sometimes hours, sometimes days) all the phones will display "Ethernet Connection Lost".  It does not appear to be a power issue or the switch rebooting because the phone's display still work.  If the switch was completely down then the phone would also be completely off.  What logging should I be turning on to troubleshoot?


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Re: Ethernet Connection Lost

When this happens, does it recover on its own or do you need to do something to restore operation?  If you do something, what?

"Ethernet connection lost" as a message on the phones could be a generic message that the phones can't communicate with their SIP gateway even though the physical link is up.

I would assume that you have one port on the switch configured as an access port on the VLAN used by the phones that connects to some type of SIP gateway, either an IP PBX, IAD, or firewall.  Look at that link and the device connected to it for issues.

On the switch, you can do a show interface and look for errors and/or something that's half-duplex.

show int | i errors

show interface | i duplex

are a good quick look, if you see something out of the ordinary scroll through to find the specific interface in trouble. 

clear counter will give you a clean slate to start from.

Not applicable

Re: Ethernet Connection Lost


I marked this post as "assumed answered," but please do not hesitate to reply if you have further questions.