03-17-2017 07:35 AM - edited 03-17-2019 09:50 AM
I have a stack of 9 3850-48P-S switches that are running version 03.06.05E of cat3k_caa-universalk9 software image.
They have IP Phones plugged in - various models, 7940, 7960, 7970, 8811, 8861 etc.
This is the typical switchport configuration:-
interface GigabitEthernet8/0/25
switchport access vlan 2
switchport mode access
switchport voice vlan 700
no mdix auto
spanning-tree portfast
spanning-tree bpduguard enable
VLAN 2 is for data and VLAN 700 is for voice - ip routing is enabled.
Observations are that when a phone is unplugged from one port and an alternate phone is plugged into the same port the switch will often refuse to power up the phone. A laptop or desktop plugged into the problem port will come up.
The only way we can resolve this at present is to shutdown and then no shutdown the port.
Has anyone any ideas on how to resolve this?
03-17-2017 07:53 PM
You can refer the following doc for troubleshooting PoE issues
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/troubleshooting/g_power_over_ethernet.html#wp1016670
Manish
03-18-2017 01:20 AM
Enable term moni on the switch and share the syslog messages which you connect the phone.
Also, if you enter the command 'show power inline' what is the output for that port.
03-21-2017 06:17 AM
It could be the port is going errdisable , have you checked that?
03-21-2017 07:42 AM
Following this thread - I have heard about this from some of our guys here but haven't been able to observe it myself or look at it further.
One of our test tools (Fluke LinkRunner AT) will test PoE at different load and draw levels, and plugging this in seems to "kick start" the port into providing power. 03.07.04E.
03-21-2017 10:22 AM
Seems related to this bug - https://bst.cloudapps.cisco.com/bugsearch/bug/CSCup05919. Neither of the releases mentioned in this thread are listed as affected versions. I would recommend opening a TAC case to see if they can tie the behavior to this bug.
Brandon
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