IE3300 POE Issue

[narshad36]

I am working on a scenario where I have Cisco IE-3300-8U2X Switch with Expansion Module IEM-3300-16P=. We have a third party phone from FHF, due to Industrial Standards this Phone supports only POE Mode B. While Cisco Switch supports POE Mode A.

We are testing by using two Ethernet Ports on Switch side, one port to send data and other port to send Power.

1- When we connect both "Data Cable" and "Power Cable" to Base Unit (IE-3300-8U2X) the Phone doesn't get power up.

2- when we connect both "Data Cable" and "Power Cable" with Expansion Module, the Phone gets powered up.

3- when we connect "Data Cable" with expansion module and "Power cable" with Expansion Module, it works perfectly.

Any advise why it is not working in scenario 1, when we connect both "Data Cable" and "Power Cable" to Base Unit (IE-3300-8U2X). Even though we tested by enabling POE only on Port where "power cable" is connected.

[pieterh]

duplicate question ?
https://community.cisco.com/t5/cisco-digital-network-architecture-dna/poe-mode-b-on-cisco-ie3300-series-switch/td-p/5004805

[narshad36]

Hi Pieterh,

This Question is different from the link you have shared above.

[pieterh]

I doubt it is,
as you are still working on the FHF phone's i't still is about 802.3bt isn't it ?

It seems a little tricky, but the section in the datasheet Cisco Catalyst IE3300 Rugged Series Data Sheet - Cisco

High-density industrial Power over Ethernet (PoE)

●  Supports ◦      up to 24x PoE/PoE+ ports or 4x 802.3bt type 4 ports (with 2.5G expansion module) with the all GE PoE enabled base [Power budget - 360W]

suggests (to me) that the switch is 802.3bt capable WHEN an 4port expansion module is added,
but the base unit itself supports only PoE/PoE+ 
have you been able to find another document that confirms the base unit is 802.3bt capable ?

by the way, a PoE switch is not designed to provide power only (without data) on a switchport
after a PD is detected, it will start with the lowest power budget possible
then the switch tries to use CDP or LLDP to detect what power the device really needs
if it get no data-signal, supplied power will be set back to the lowest class or in worst case power is  switched off again

here the same question: what appears in the switches logging ?

[narshad36]

Now Question is not about 802.3bt.

Now Question is about Lets say Base unit is POE/POE+ Capable. I connect two UTP Patch Cords with Switch. On One Port I disable POE as I just want Data to go through it. On Second Port, I enabled POE as I want Power to travel through it. I hope It Makes sense.

But with this Phone Doesn't get powered up. 

But When I connect One UTP Cable with Base Unit and Other on Expansion Module, Phone gets powered up. My Question is why Phone not getting powered up when we connect it with Base Unit.

[pieterh]

the primary function of a PoE switch is to provide network connectivity
and as a secundary  function provide power to that device,
=>  it is NOT a stand-alone power source

if you do try this you get unpredictable results, as this is not the intended way to use this switch

I forgot to mention for some PoE devices (>30W) 4-pair connection is mandatory
Verify Differences between PoE 802.3AT/802.3BT on Catalyst 9000 - Cisco

	PoE	PoE+	UPoE	UPoE+
IEEE standard	802.3af	802.3at	Cisco proprietary (802.3bt based)	802.3bt
Type Designation	Type 1	Type 2	Type 3	Type 4
Maximum power per interface	15.4W	30W	60W	90W
Number of twisted pairs used	2	2	4	4