cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
340
Views
55
Helpful
21
Replies
Highlighted
Beginner

Enabling POE+ in Cisco Switch

I have Cisco 2960 switch. I want to enable POE+ on this switch.

Is there any special command which will enable POE+ in the switch ? If so please let me know how to enable POE+

21 REPLIES 21
Highlighted
Hall of Fame Community Legend

Re: Enabling POE+ in Cisco Switch

If the switch supports PoE then the feature is enabled natively.

Highlighted
Beginner

Re: Enabling POE+ in Cisco Switch

Thanks.

So if natively enabled how it is decided to use POE or POE+ ?

Is it based on the end device which connects to the switch port & how much power it requires ?

Is it totally depending on the end device power requirement ?

Highlighted
Hall of Fame Community Legend

Re: Enabling POE+ in Cisco Switch

End device must either talk CDP or LLDP.
If the end device talks CDP then the end device will "talk" with the switch how much it wants to draw. If the end device talks LLDP, then LLDP must be enabled (disabled by default) on the port.
WARNING: 3650/3850, Catalyst 9K switches do not "like" both LLDP and CDP enabled on the same port. Use only one.
If the End device does not support CDP nor LLDP and uses >15.4w then you have to manually configure how much power to "feed" to the end device.
Highlighted
Beginner

Re: Enabling POE+ in Cisco Switch

Thanks. Understood.

My device does not support both CDP & LLDP. Let me know what is the command to manually configure how much power to "feed" to the end device. 

Highlighted
VIP Expert

Re: Enabling POE+ in Cisco Switch

Hi,

Try this command under the interface that is connected to the device and assign power to a statically.

power inline static max xxxx

HTH 

Highlighted
Beginner

Re: Enabling POE+ in Cisco Switch

The device which I am going to connect has the attached specification.

So what should i do for this to work.

There will be around 20 such devices which will be connected to 48 port switch.

So my understanding is that i need to manually confgure the below command in each of the 20 switch port.

 

power inline static max 19000

 

Let me know if my understanding is right.

 

Highlighted
Beginner

Re: Enabling POE+ in Cisco Switch

Any input r help

Highlighted
Hall of Fame Community Legend

Re: Enabling POE+ in Cisco Switch

I'd recommend configuring the port for 25.0w.
Highlighted
Beginner

Re: Enabling POE+ in Cisco Switch

Thanks. Could you please explain the reason for your recommendation ?

Highlighted
Hall of Fame Community Legend

Re: Enabling POE+ in Cisco Switch

Let me start by saying one cannot "fry" a device by shoving too much PoE down the line.
To answer your question, notice the device specifications says "25.0w"? That's the "norm" of what the device can take. What happens if you only enable 19.0w and some of the functions don't work properly?
Highlighted
Rising star

Re: Enabling POE+ in Cisco Switch

CDP & LLDP only happen AFTER the device has powered up.  PoE/PoE+ uses a more 'basic' mechanism that has to kick in first. You don't need to manually configure the power on any of the interfaces assuming you aren't planning to oversubscribe the PoE on the switch.  Once the PD device has booted then CDP/LLDP can do additional things that aren't possible with the 802.3af/at standard.

Read this https://en.wikipedia.org/wiki/Power_over_Ethernet  and the other post with a link to the 3750 PoE troubleshooting.

 

Andy

Highlighted
Beginner

Re: Enabling POE+ in Cisco Switch

so for devices which does not support CDP/LLDP , i have to manually set the required power on the interfaces if the requirement is more than 15.4W

Hall of Fame Community Legend

Re: Enabling POE+ in Cisco Switch

Correct.
Highlighted
Rising star

Re: Enabling POE+ in Cisco Switch

No, you do not need to manually set the power.  The 802.3af/at mechanism will negotiate the Class of the attached PD device.  LLDP is optional and allows for more granular power requirements.  The five classes (0 - 4) allow for 15.4W, 4W, 7W, 15.4W and 30W respectively (Class 0 is for a device that doesn't support 802.3af/at Class negotiation).  Once a device has booted CDP/LLDP can signal more granular requirements.

If your devices don't signal their PD class - i.e. they are Class 0 - then they will be allocated 15.4W.  Any 802.3at PD Class 4 device should be detected as a Class 4 device.  If it doesn't then it isn't complying with the standard and I'd be reluctant to plug it in...

A bit more detail here - https://www.cisco.com/en/US/docs/switches/lan/catalyst3850/software/release/3.2_0_se/multibook/configuration_guide/b_consolidated_config_guide_3850_chapter_011010.html

A device that is detected as Class 4 will initially be allocated 15.4W only.  Once its booted and CDP or LLDP kick in it can request more power up to 30W.  If your Class 4 device doesn't support CDP or LLDP then it will only be allocated 15.4W.  I am guessing a prerequisite for 802.3at is LLDP support on the PD (or at least that is what the Catalyst is expecting).  Are you sure your device doesn't support LLDP?  Have you enabled LLDP on the switch as it isn't on by default.

Some notes here that are similar I think - https://community.ui.com/questions/Workaround-for-UAP-AC-802-3at-non-compliance-POE-power-problems-reboots-for-newer-Cisco-catalyst-/baf59f23-e89c-4042-8349-d05b6e3e95b7

 

 

CreatePlease to create content
Content for Community-Ad