Hello,
I have 2 SG500 52 port switches in a stack. One is non-POE and the other is POE. I use the POE switches primarily to drive our Yealink T22P and T46G phones. They have worked flawlessly for about a year.
This weekend I updated the firmware and boot for the switches to the latest release.
SG500#sh ver
Unit SW version Boot version HW version
------------------- ------------------- ------------------- -------------------
1 1.4.0.88 1.4.0.02 V02
2 1.4.0.88 1.4.0.02 V02
Now all of a sudden a port that is being used to power one of the phones isn't working correctly, and the behavior is VERY odd (I will explain in a second). I have 20+ phones on this same POE switch that have no issues. I'm WELL under power budget since each phone draws about 2.5W.
Any phone that is plugged into this bad port at first looks like it works fine. It is in the right VLAN, auto smartport correctly identifies it, LLDAP-MED works as it should. The phone looks to be operational. It even might work fine for a while. But eventually when making a call the light in the screen starts flickering like crazy and you get a "static" sound on both ends of a call. It sounds like electrical interference. I can make a call and it will be fine for 1 minute and the next it starts doing this. It is NOT the phone. The same phone in a different switch port does not do this (in fact 20 others phones on different ports don't do it). ANY phone in this port shows this behavior.
The port in question (port 36), is showing Local POE as 0 Watts, Remote POE 2.9W (in Administration -> Discovery-LLDP -> LLDP Port Status). All other phones show Local POE as something like 2.5W. All settings on this port (36) are exactly the same as the rest of the ports on the switch that work fine with the EXACT same phones. I know it is the port on the switch that is causing the issue as well because I was able to isolate it. I tested the phone by plugging the phone that appears to be bad into a different wall outlet. I tested the wall outlet by switching the cables from the patch panel to the switch ports. I changed the patch cables as well. It is the switch port for a fact.
I did some searching and found some similar info related to the SG300. So I ran some of those commands and found some more info.
SG500#show power inline gi2/1/36
Port Powered Device State Status Priority Class
-------- -------------------- ---------------- ------------ -------- ---------
gi2/1/36 Auto Searching low class4
Time range:
Power limit: 30.0 W
Inrush Test: Enable
Legacy Mode: Enable
Port Status: Port is off - detection is in process
Overload Counter: 0
Short Counter: 0
Denied Counter: 2
Absent Counter: 0
Invalid Signature Counter: 1
Notice the port status (it shows this all the time) and the Class.
This is compared to the same phone in a different port showing this;
SG500#show power inline gi2/1/22
Port Powered Device State Status Priority Class
-------- -------------------- ---------------- ------------ -------- ---------
gi2/1/22 Auto On low class2
Time range:
Power limit: 30.0 W
Inrush Test: Enable
Legacy Mode: Enable
Port Status: Port is on - valid capacitor/resistor detected
Overload Counter: 0
Short Counter: 0
Denied Counter: 0
Absent Counter: 5
Invalid Signature Counter: 0
I am afraid to make any changes across all ports on the switch since they are working fine. So I am trying to make changes on just port 36 of this switch. I tried turning off EEE settings, didn't help. Tried turning off the VLAN and auto smartport settings, didn't help.
Is the port busted (if so I'm pretty upset with the purchase of this switch)? Is it something caused by the latest firmware?
In 15 years I haven't had a single faulty piece of hardware. If this is I sure hope Cisco is easy to deal with.
