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IPM and restricted mode on 802.3at Aruba APs

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

Aruba Employee

Re: IPM and restricted mode on 802.3at Aruba APs

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


Charlie Clemmer
Aruba Customer Engineering

Re: IPM and restricted mode on 802.3at Aruba APs

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

Aruba Employee

Re: IPM and restricted mode on 802.3at Aruba APs

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


Charlie Clemmer
Aruba Customer Engineering

Re: IPM and restricted mode on 802.3at Aruba APs

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

Aruba Employee

Re: IPM and restricted mode on 802.3at Aruba APs


@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.


Charlie Clemmer
Aruba Customer Engineering

Re: IPM and restricted mode on 802.3at Aruba APs

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
Aruba

Re: IPM and restricted mode on 802.3at Aruba APs

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.

/Onno
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