Hi,
We recently upgraded old cisco switches with the new 3850 as the old ones had reached EoL. In doing this, all went fine except there is one a small PABX which has analog phones plugged into it started having weird issues. Users started complaining about intermittent one way speech, sometimes phones having no dial tone, so on and so forth and rest of the times phones work just fine.
This mini PABX has only one uplink which goes to the 3850 switch which then connected through various hops of switches to the main PABX where other phones like IP phones and DECT registers.
We checked for logs on the switch but nothing showed up there which could indicate something.
We are seeing this issue only at places which has new 3850, the places which is still relying on the older switches (3750) are working fine.
3750 had 10/100 ports, so the old set up was running smoothly on auto speed. Initially we had the same auto set up on new 3850, and it was showing no alarms or complains on the port, however, since we saw this issue we tried to lock it to 100 M manual. Still no luck. So we changed the port setting to auto 10/100 only, still the same.
Has anyone seen this issue? or if you have any suggestions to help troubleshoot this issue?
The ios running on the 3850 is 3.2.3 SE.
