PoE Problem SG350X and Cisco 8851 + 1KEM

[dennis.bornemann]

We have a Cisco SG350-28P 28-Port Gigabit PoE Managed Switch on a Customer Site witch have to provide Power over Ethernet to the Desk Phones (Series 8800). The normal phones (8851) are working as expected. But the Phones with the digital Key Expansion Module attached don't get enough power for enabling the KEM. As Documents say normal PoE should be enough for powering one Module.

We have updated the Switch to the newest Software Version 2.4.0.94 but it doens't help.

The Switch Logs don't show any error for PoE. Only the Phones display on startup that they can't enable the KEM because of insufficent Power.

Have someone a solution for that problem?

[Georg Pauwen]

Hello,

try and use Power Mode --> Class Limit (page 167 of the attached manual).

https://www.cisco.com/c/dam/en/us/td/docs/switches/lan/csbms/350xg/admin_guide/AG_Tesla_350_550.pdf

[dennis.bornemann]

That is the active Setting under Port Management -> PoE -> Properties.

I have also tried Port Limit but no change. KEM not powering up

[Georg Pauwen]

What if you increase the power allocation ?

Port Management > PoE > Settings --> Administrative Power Allocation (mW)

[dennis.bornemann]

Under PoE -> Settings -> Port X i can't change Power Allocation. It's seems thats this is only informational.

[Georg Pauwen]

Hello,

I think you need to have 'Port Limit' configured in order to change that value...

[dennis.bornemann]

Hello,

i have now changed the Power Setting to Port Limit. Now i can change the Power Allocation - But this is set to the max of 30000 mW

[Georg Pauwen]

Hello,

according to Table 4 in the attached document, you need 802.3at PoE. Check if you can change that somewhere in the settings of the switch...

https://www.cisco.com/c/en/us/products/collateral/collaboration-endpoints/ip-phone-8800-series-key-expansion-module/datasheet-c78-732356.html

[dennis.bornemann]

The Switchport is running with following power setting:

Entry No.	Port	Administrative Status	Operational Status	Time Range		Priority Level	Administrative Power Allocation (mW)	Force Four Pair	Power Consumption (mW)	Class	PoE Standard
				Name	State
6	GE6	Enabled	Delivering-Power			LOW	30000		3400	4	802.3 AT

When i plug the phone incl. the KEM in a switch port on the old phone system (UC540) the phone with the KEM boots up.

Normaly it should run aroung 9-12 watts with that module.

[Georg Pauwen]

Hello,

are you running firmware 10.2(2) or later on your phones ?

[dennis.bornemann]

I'm running currently firmware sip88xx.12-1-1SR1-4

[Georg Pauwen]

Hello,

for some reason the KEM is not compatible. I cannot find any information on whether it should or should not be.

If possible, try and downgrade your firmware to a 2.3, 2.2., or 2.1 release, and check if that makes a difference. Not very good advice, I know, as it is pretty much trial and error... 

[dennis.bornemann]

Hello,

i have tried to downgrade the software on that switch. With Version 2.2 the problem still exists. After the Downgrade to 2.1 the switch didn't boot up again. Now the System stuck in a boot loop. With the console i see following error:

%HAL_config_poe-F-POEInitError: HALP_config_poe_692xx_check_master_reset: HALP_config_poe_number_of_poe_devices is Zero: Failed on init.

***** FATAL ERROR *****
Reporting Task: HCPT.
Software Version: 2.1.0.63 (date Jan 17 2016 time 14:41:37)
ros(HOSTG_fatal_error+0x14) [0x233edc]
ros(OSSYSG_fatal_error+0x148) [0x74d430]
ros() [0x582800]
ros(HALP_config_poe_692xx_dev_op_set_periodic+0x580) [0xa11a38]
ros() [0xa058f4]
ros(HALP_config_poe_691xx_692xx_poe_dev_operation+0x48) [0xa059d8]
ros(HALC_config_poe_dev_operation+0x44) [0xa15044]
ros() [0x9bc26c]
ros(HALC_config_device_dispatch+0x1a4) [0x9c114c]
ros() [0x9d8ae8]
ros() [0x9d8cf4]
ros() [0x9d8d4c]
/lib/libp2linux.so.1(+0x3aa4) [0xb6ed5aa4]
/lib/libpthread.so.0(+0x6e64) [0xb6eb0e64]

***** END OF FATAL ERROR *****

This error is linked to Cisco BUG ID CSCvk62334 and the workaround is a RMA. So we will do this and let you know if the problem wie the poe provisioning for the Cisco IP Phone 8851 + 1 KEM still exists.

For now thank you for your help