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Can i Change the PoE Class from 4 to 3


Userlevel 1
Hi,

I have IP cameras that are running at Class 4 power (which are not working)
I have IP cameras that are running at Class 3 power (which are working)

Any idea if i can stop auto negotiate the power settings and change class?

Thanks

6 replies

Userlevel 4
Very often these cameras need LLDP-MED. Which cameras do you use ?

/ André
Userlevel 4
This is a config snippet that could help:

configure lldp port 1 advertise port-description
configure lldp port 1 advertise system-name
configure lldp port 1 advertise system-capabilities
configure lldp port 1 advertise management-address
configure lldp port 1 advertise vendor-specific dot3 power-via-mdi with-classification
configure lldp port 1 advertise vendor-specific med capabilities
configure lldp port 1 advertise vendor-specific med power-via-mdi

/ André
Userlevel 1
André Herkenrath wrote:

This is a config snippet that could help:

configure lldp port 1 advertise port-description
configure lldp port 1 advertise system-name
configure lldp port 1 advertise system-capabilities
configure lldp port 1 advertise management-address
configure lldp port 1 advertise vendor-specific dot3 power-via-mdi with-classification
configure lldp port 1 advertise vendor-specific med capabilities
configure lldp port 1 advertise vendor-specific med power-via-mdi

/ André

tried and nothing changed.
Userlevel 7
While enabling LLDP may help in this case, I would not expect a camera that is classifying as class 4 to suddenly start reporting itself as class 3.

The class is not something that can be changed on the switch, but rather what the PoE device reports to the switch when it connects.

You may want to take a look at the following article for a more in-depth explanation of this:
https://gtacknowledge.extremenetworks.com/articles/Q_A/How-does-PoE-device-classification-work

Regarding this specific issue, if I had to take a guess (without knowing what switch is powering these cameras), I would guess that the switch may not support two-event classification in hardware, requiring LLDP for classification of PoE+ devices. In this case, enabling the LLDP config that Andre mentioned should help.
Userlevel 1
I have AXIS cameras - some work ok and negotiate at class3 some negotiate at class4

switch is X440-24p
Userlevel 7
http://www.axis.com/academy/installation_challenges/poe.htm

"Some cameras are specified with two different classes of PoE. This is because products can require different wattages, depending on whether they are used with or without extra equipment, such as heating or cooling. The first PoE number specifies the wattage for the product itself, whereas the second number specifies the wattage needed for the product, including extra equipment. The AXIS P13xx-E is an enclosed product, and is specified as "PoE IEEE 802.3af max. 12.95 W or High PoE max 25.5 W"."

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