CP-8851 + 8800 KEM with Asterisk-based IP PBX

[J0hannesR]

Good morning everyone,

I encounter a problem during my PoC Project with Wazo (a fork of Xivo Asterisk-based IP PBX.

I have three IP Phones : 2 SPA152G (works) and 1 CP-8851 + 8800 KEM (don't work).

Our team has configured SEP file and the 8851 turn on with several line buttons.

Unfortunately, the KEM doesn't start : 8851 indicates (in french sorry, I try to translate approximately)

"this phone can not power this equipment".

We try this a generic power injector and a spare Cisco power injector from wireless AP.

We do not want to use a proprietary IPBX :)

Could you help us if this problem come from SEP file or hardware problem ?

Thank you in advance.

[R0g22]

Did your team edit the SEP file correctly to add module config in it ?

[J0hannesR]

Ok, that's a beautiful sentence but I don't know more after that :)

I need to obtain a solution for buying my other IP Phones.

Do you need SEP file or other thing ?

Why PoE doesn't work (in datasheet, 2 KEM can be powered with CP-8851 POE) ?

In our SEP file, we have provide this information for the KEM :

<addOnModules>   
      <addOnModule idx="2">
         <deviceType>KEM</deviceType>
         <deviceLine>36</deviceLine>
      </addOnModule>
   </addOnModules>

We try KEM and BEKEM for "deviceType".... but nothing has work.

Thanks in advance for your help :D
Regards.
J0hannesR

[R0g22]

2 KEM's with POE on a 8851 requires a power cube, though there is an exception to this as well. Are you using a Cisco switch ?

[R0g22]

Can you check the version on the back of the IP Phone ? There should be a TIN/PID label. Phones should be V08 or higher to power up multiple KEM's using 802.3at.
From the error that you highlighted, the KEM's are not even powering up properly at the moment.

[J0hannesR]

First of all, we use only one KEM on our CP-8851.

Secondly, we don't have cube power. We try to power our CP-8851 with power injector AIR-PWRINJ4= (only this type of Cisco injector in spare).

IP Phone version is V08.

Unfortunately, our network is composed of several contenders DL...k switches.

In our SEP file, these following variables are corrects :

<deviceType>KEM</deviceType>   KEM or BEKEM ??
  <deviceLine>36</deviceLine>  36 seems correct ((9*2columns)*2 pages).

From your point of view, do you think the problem comes from our manual SEP file ?

[R0g22]

The addon module section needs to be -

<addOnModules>
<addOnModule idx="1">
<deviceType>BEKEM</deviceType>
<deviceLine>36</deviceLine>
<loadInformation></loadInformation>
</addOnModule>
</addOnModules>

Next for the power up issue, on your switch can you check how much power is being provided/requested by the phone during power up ?
If that does not help, then we need to session into the phone and take debugs from the shell.

[J0hannesR]

I tried with your configuration... and our Expansion Module is still off.

Please find below information about POE Port used by the CP-8851.

High Power Mode : 802.3af

Class : 4

Output Voltage (Volt) : 54.7

Output Power (Watt): 71

Output Current (mA) : 3.9

Power Limit : 15400

Status : DeliveringPower

(on a NetGear GS752TP. Sorry, my colleague does not purchase Cisco products before I joined team :) ).

Maybe, another information could help our troubleshooting : CP-8851 embedded IOS for unified Communication. We have flashed the IP Phone with an official SIP IOS : sip88xx.12-0-1SR1-1.

Thank you for all your help.

[R0g22]

Your switch port is providing 71W ? That's way too much. 802.3af has maximnum power of around 15W with cable dissipation this would be around 13W.

My config will not help if the module cannot be powered properly. I am not in office today. I will send you the steps to get phone debug shell logs tomorrow. That will give more insight why the KEM is not being powered properly.

[J0hannesR]

Oh sorry, I think that I made a mistake :)

So, in the correct order :

High Power Mode : 802.3af

Class : 4

Output Voltage (Volt) : 54.7

Output Current (mA) : 71

Output Power (Watt) : 3.9

Power Limit : 15400

Status : DeliveringPower


Thank you so much for all your help.
I await your news tomorrow and I will come back here to explain solution if KEM work properly.

[R0g22]

Adding the analysis here. PM is failing. The logs are not complete but there is still relevant information in here -

6119 NOT Mar 02 08:07:12.673759 (378:392) PWRMAN-eventPwrNeg():
6120 NOT Mar 02 08:07:12.673772 (378:392) PWRMAN-eventPwrNeg(): curReq.valid: 1 info->curPwr: 8500 curReq.newPwr: 11500
6121 WRN Mar 02 08:07:12.673785 (378:392) PWRMAN-eventPwrNeg(): power neg failed: TIMEOUT
6128 NOT Mar 02 08:07:12.679643 (436:655) DMAN-isPowerAvailable(): Response from PM: NO POWER
6129 NOT Mar 02 08:07:12.680300 (436:655) DMAN-lkemHandler(): Power Request for KEM Rejected.

The phone initially get 8.5 W power and upon KEM detection requests an additional 3 W i.e. 11.5 W. Power negotiation to this new power fails.

[J0hannesR]

Hi Nipun,

Thank you for your analysis.

I think that no switch in my company provides POE power enough.

Two of my biggest switches are NetGear GS752TP ...

GS752TP datasheet :

PoE budget (PSU/Passthrough) : 384W
This switch have 48 ports, is around 8W per port.

Could you provide me the Cisco external power reference please ? (Cube ?)

In this way, I will buy several for my CP-8851 IP Phone with KEM.

Thanks in advance.

Have a nice day.

[R0g22]

So that isolates as to why the KEM is not being powered. For power cube you can reference Table 3 in the 8851 Data sheet linked below -
https://www.cisco.com/c/en/us/products/collateral/collaboration-endpoints/unified-ip-phone-8800-series/datasheet-c78-731667.html

[J0hannesR · Accepted solution]

Hi Nipun, Hi EveryBody,

So, my switches are THE PROBLEM !

I change my strategy : in my company, I deploy only 2 CP-8851+KEM8800 (others are CP-8851 without KEM or SPA512G). I prefer to buy two external power Cube to resolve this problem.

In my case, I am in Switzerland and my electrical cord is different :)

I am ordering two CP-PWR-CUBE-4 and two CH  CP-PWR-CORD-SW (SW for Switzerland).

I hope it will help someone.

Stay Connected !
Johannes