Wireless Access

Hi guys,

 

I have a customer that has PoE switches, and I have to implement a network with APs 315. This AP is 802.3af/at compliant, but when powered with 802.3af PoE source may enter in power-save mode. But the datasheet isn't very specific:

 

--Unrestricted functionality with 802.3at PoE
--When using IPM, the AP may enter power-save mode
with reduced functionality when powered by an 802.3af
PoE source (see details on Intelligent Power Monitoring
elsewhere in this datasheet)

 

• Intelligent Power Monitoring (IPM):
--Enables the AP to continuously monitor and report
its actual power consumption and optionally make
autonomous decisions to disable certain capabilities.
--For the 310 Series Access Points, the IPM power-save
feature applies when the unit is powered by an 802.3af
PoE source. By default, the USB interface will be the first
feature to turn off if AP power consumption will exceed
the available power budget. In rare cases it may be
necessary to take additional power saving measures, but
in most cases, the 310 Series Access Points will operate in
unrestricted mode.

 

Although the datasheet says in most cases the AP will operate in unrestricted mode, it also says it may be necessary to disable certain capabilities, but it doesn't say anything else.

Do you know what are these capabilities that can be disabled? What can be impacted? I need to know this to consider to keep the same switches or replace them with PoE+ ones. Many thanks!

 

Regards,

Julián

Further down in the data sheet, there's a section labeled Power Sources and Consumption which should provide the details you're after:

 

Power over Ethernet (PoE): 48 Vdc (nominal)

802.3af/802.3at compliant source

--Unrestricted functionality with 802.3at PoE

--When using IPM, the AP may enter power-save mode

with reduced functionality when powered by an 802.3af

PoE source (see details on Intelligent Power Monitoring

elsewhere in this datasheet)

--Without IPM, the USB port is disabled and transmit

power of the 2.4 GHz radio chains is reduced by 3dB

to 15dBm max when the AP is powered by and 802.3af

PoE source

Hi Charlie,

 

Yes, I know, I saw it:

 

--Without IPM, the USB port is disabled and transmit

power of the 2.4 GHz radio chains is reduced by 3dB

to 15dBm max when the AP is powered by and 802.3af

PoE source

 

Here the power is reduced by 3 db in the 2.4 GHz radio. But I suppose is better to use IPM, and with IPM certain capabilities may be disabled, and the datasheet doesn't specify what are these capabilities.

 

Regards,

Julián

With IPM, rather than a static profile based on the worst case power, the IPM priorities can be set by the user. The user guide lists the various options, although some options may not be relevant to the AP-315 (like disabling pse or disabling the second ethernet port).

 

To enable IPM:

(Instant AP)(config)# ipm

(Instant AP)(ipm)# enable

To alter the IPM priority list:

(Instant AP)(ipm)# ipm-power-reduction-step-prio ipm-step ?

cpu_throttle_25 Reduce CPU frequency to 25%

cpu_throttle_50 Reduce CPU frequency to 50%

cpu_throttle_75 Reduce CPU frequency to 75%

disable_alt_eth Disable 2nd Ethernet port

disable_pse Disable PSE

disable_usb Disable USB

radio_2ghz_chain_1x1 Reduce 2GHz chains to 1x1

radio_2ghz_chain_2x2 Reduce 2GHz chains to 2x2

radio_2ghz_chain_3x3 Reduce 2GHz chains to 3x3

radio_2ghz_power_3dB Reduce 2GHz radio power by 3dB from maximum

radio_2ghz_power_6dB Reduce 2GHz radio power by 6dB from maximum

radio_5ghz_chain_1x1 Reduce 5GHz chains to 1x1

radio_5ghz_chain_2x2 Reduce 5GHz chains to 2x2

radio_5ghz_chain_3x3 Reduce 5GHz chains to 3x3

radio_5ghz_power_3dB Reduce 5GHz radio power by 3dB from maximum

radio_5ghz_power_6dB Reduce 5GHz radio power by 6dB from maximum

Hi Charlie,

 

That's what I was looking for and that does specify those capabilities. I didn't know that information was in the Instant User Guide. Many thanks!

 

Regards,

Julián

---

@fjulianom wrote:

 

That's what I was looking for and that does specify those capabilities. I didn't know that information was in the Instant User Guide. Many thanks!

---

I was actually trying to find it in the controller user guide, but Instant was the first thing I pulled up. :)  Glad that helps.

Hi Charlie,

One more thing about this, if I don't enable IPM:

--Without IPM, the USB port is disabled and transmit
power of the 2.4 GHz radio chains is reduced by 3dB
to 15dBm max when the AP is powered by and 802.3af
PoE source.

Only this will happen? Though with a max. transmit power of 15 dBm in 2.4 GHz, the radio will keep transmitting in 2x2:2? And no more restrictions will take place (continue with 4x4:4, 24 dBm in 5 GHz), etc.? If so, it is fine for me since I don't use the USB port and the network isn't design to transmit at maximum power at 2.4 GHz.

Regards,
Julián

That is correct. The (worst case) power budget for this AP model only just exceeds what's available from 802.3af POE (assuming CAT5E or better cabling). Disabling USB and limiting the two 2.4GHz radio chains to 15dBm is sufficient to meet that requirement.

Hi Onno,

 

Then, I understand the following:

 

- Disabling USB and limiting the two 2.4GHz radio chains to 15dBm is sufficient for not exceeding what's available from 802.3af PoE source, and guarantees the rest of functionalities will be unrestricted.

 

- Otherwise, enable IPM and the AP will restrict some functionalities according to the IPM list (only in the case the AP exceeds the worst case power budget).

 

Thanks and sorry for the late reply,

Julián

Hi!

 

I recently found out that with the new AP 5xx Series IPM becomes even more important. There is a "Tip of the week" article available at https://afp.arubanetworks.com/afp/images/b/b4/Tip_of_the_Week_3_-_6-22-18_-_Intelligent_Power_Management.pdf with a more detailed explanation of the possible IPM configurations.

 

Starting with Instant AOS 8.5.0.0_70258 the System Status with a 802.3af powered AP-515 and IPM enabled shows a solid RED Systems Status LED (which should be AMBER as observed with 8.4.0.0). With "show ap debug system-status" the following Power Status is reported:

 

Power Status
------------
Item                        Value
----                        -----
Power Supply                : POE-AF
LLDP Power                  : Successfully negotiated at 13.0W
Current Operational State   : USB enabled, eth1 disabled, All radios disabled
Eth0 HW POE status          : POE AF, LLDP power: 13.0W

 

But that's not correct:

Both radios are working normally

 

My questions:

- How is the default IPM priority configuration?

- Do I have to configure all priorities with "ipm-power-reduction-step-prio ipm-step" to make sure that the customers requirements are met.
- Is there a show command for the IPM configuration?

 

With kind regards

Manfred M.

 

Update:

 

I have adjusted the IPM priorities as follows:

AP08 (config) # ipm
AP08 (ipm) #

ipm-power-reduction-step-prio ipm-step disable_usb priority 6
ipm-power-reduction-step-prio ipm-step disable_alt_eth priority 5
ipm-power-reduction-step-prio ipm-step radio_2ghz_chain_2x2 priority 4
ipm-power-reduction-step-prio ipm-step cpu_throttle_25 priority 3
ipm-power-reduction-step-prio ipm-step cpu_throttle_50 priority 2
ipm-power-reduction-step-prio ipm-step cpu_throttle_75 priority 1

 

After committing this changes the System Status LED on the AP-515 turned to Green and the Power Status reports that there are no more restrictions on the radios:

 

Power Status

------------

Item                       Value

----                       -----

Power Supply               : POE-AF

LLDP Power                 : Successfully negotiated at 13.0W

Current Operational State   : 2.4GHz radio: No restrictions, 5GHz radio: No restrictions

Eth0 HW POE status         : POE AF, LLDP power: 13.0W

 

What is interesting:

The System Status does not reflect that anything is disabled.

But eth1 and USB are disabled.

 

What is not clear to me regarding the "Tip of the Week" document:

 

The following options are available within the IPM config:

‘cpu_throttle_25’ Reduce CPU frequency to 25%

‘cpu_throttle_50’ Reduce CPU frequency to 50%

‘cpu_throttle_75’ Reduce CPU frequency to 75%

 

In terms of priority, the higher priority assigned to a setting would be a lower value. A priority value of ‘4’ would be applied before a priority value of ‘1’, etc. Additionally, on settings that apply to the same feature (CPU, radio chains, etc), they should be prioritized accordingly so that the lower-impact setting is applied before the higher impact setting.

 

So the correct priorities - in contrast to the documented example - should therefore be:

ipm-power-reduction-step-prio ipm-step cpu_throttle_75 priority 3
ipm-power-reduction-step-prio ipm-step cpu_throttle_50 priority 2
ipm-power-reduction-step-prio ipm-step cpu_throttle_25 priority 1

 

With regards

Manfred M.

 

 

Manfred,

Not trying to second-guess your comments, but how did you confirm that USB and E1 are disabled (by IPM)?

Manfred,

Note that the highest priority IPM item (lowest prio number) is the one that is applied first. So in your case, the first thing that should happen is throttle the CPU to 75%.

Also, what's the status (color) of the system LED?

Hi!

Thank you for your Reply. That's an important point to me.

Setting the priority did not immediately show the results. Only the System LED turned to Green immediately.

 

The Power Status now is:

 

Power Status
------------
Item                        Value
----                        -----
Power Supply                : POE-AF
LLDP Power                  : Successfully negotiated at 13.0W
Current Operational State   : 1 ETH port disabled; USB power disabled; 2.4GHz radio: No restrictions, 5GHz radio: No restrictions, CPU at 25%
Eth0 HW POE status          : POE AF, LLDP power: 13.0W

 

I'm now a little bit confused about the priority value you set with the command because you are telling me the opposite compared to the statements of the "Tip of the Week" Article.

 

Tips of the Week article:

In terms of priority, the higher priority assigned to a setting would be a lower value. A priority value of ‘4’ would be applied before a priority value of ‘1’.

 

User Guide:
Setting a low-priority value for a power reduction step reduces the power level sooner than setting a highpriority value for a power reduction step.

Your statement:

Note that the highest priority IPM item (lowest prio number) is the one that is applied first. So in your case, the first thing that should happen is throttle the CPU to 75%.

 

The settings now are as follows:

ipm
 enable
 ipm-power-reduction-step-prio ipm-step cpu_throttle_75 priority 1
 ipm-power-reduction-step-prio ipm-step cpu_throttle_50 priority 2
 ipm-power-reduction-step-prio ipm-step cpu_throttle_25 priority 3
 ipm-power-reduction-step-prio ipm-step radio_2ghz_chain_2x2 priority 4
 ipm-power-reduction-step-prio ipm-step disable_alt_eth priority 5
 ipm-power-reduction-step-prio ipm-step disable_usb priority 6

 

With kind regards

Manfred

The tip of the week will be getting updated today to correct for that. I wrote that, was a transposition error. I will be correcting that and adding the content about the 555. 

 

And I agree, it's very confusing but apparently that is the best logic that is possible for the hardware.

 

Hi Jerrod!

 

Thank you for the clarification in the updated "Tip of the week" article which now includes all needed information about IPM and PoE. Works now as designed in my installations.

 

Link to Tip of the Week article:
https://afp.arubanetworks.com/afp/images/b/b4/Tip_of_the_Week_3_-_6-22-18_-_Intelligent_Power_Management.pdf

 

PS:

Thank you for your Mesh Deep Dive Session @Atmosphere in Croatia - good to hear that almost all of your best practices are also already my best practices...

 

Manfred M.