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How many PoE ports are supported by MS128-8FP

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Conversationalist

How many PoE ports are supported by MS128-8FP

I am working out in deployment for solution Wi-Fi, I am proposing connect eight Access Points MR52 in the 8 ports of MS120-8FP. I want to know if they operate correctly or I need to propose a higher power poe switch?

 

Could you help in this quiestion!

 

Regards.

1 ACCEPTED SOLUTION

Accepted Solutions
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Meraki Employee

Re: How many PoE ports are supported by MS128-8FP

Hi @angeloPV9 they will operate fine.  While the MR52 APs will want to see and negotiate 30W PoE+ power upon bootup, they will never draw more than 21 watts maximum, and in all likelihood they will average between 6 to 12 watts, but keep an eye on it to confirm.  

 

Go to the Switch > Switches page and click into the switch and click on the power tab.  You will see a "Consumption" section and a "Budgeted" section.  The number to worry about is the consumption. The budgeted number is just reflecting the total amount of theoretical power that could be consumed, as if every device pulled the full 15 or 30 watts of power it advertised via CDP/LLDP when it first negotiated.

 

See attached screen shot.  I have a compact MS220-8P switch running 7 PoE devices all the time (MV cameras and MR APs).  Looks at my "Budgeted" section, it says 140W/124W.  That's showing that the switch max budget is 124W of PoE power, and those 7 devices (at max power draw) would take 140W.  That's because 2 of my devices are an MV72 and an MR52 both of which negotiated 30W, and the other 5 devices negotiated 16W, so there's the 140W number.  It rounds 15.4W to 16W when doing this to err on the conservative side. 

 

But notice the consumption tends to hover around 41 to 45 watts.  Will that fluctuate?  Sure.  I don't watch it that closely, but I've never seen it over 60 watts, not even halfway to the max the switch can deliver.

 

Hope that helps!

MS220-8P-Power.jpg

View solution in original post

8 REPLIES 8
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Head in the Cloud

Re: How many PoE ports are supported by MS128-8FP

Power will be fine, but 8 MR's on an 8 port switch means you need to use one of the SFP ports for uplink.

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Conversationalist

Re: How many PoE ports are supported by MS128-8FP

Hi Brandom yes that is right we are going to connect a fiber for uplink, so I am proposing this switch. Do you know if is there a launch calculator like switches cisco for simulate poe demand?

 

 

Thank for your answer, Regards

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Kind of a big deal

Re: How many PoE ports are supported by MS128-8FP

Hmm, actually. Now I am curious

MR52 has the following power requirements:
(802.3at required; functionality-restricted 802.3af mode supported)

MS128-8FP is showing the following for PoE/PoE+ capabilities
MS120-8 FP includes 124W PoE/PoE+
Up to 30W per port

Not sure how it can do 30W per port for all of them, since 124W / 8 = 15.5W

Or am i misunderstanding something?
Nolan Herring | nolanwifi.com
TwitterLinkedIn
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Kind of a big deal
Kind of a big deal

Re: How many PoE ports are supported by MS128-8FP

I dont know  what  the mr52  takes to boot and operate. 

The ms  can go up to 30w  per port.  But when its  out of poe  budget  the last port(s) stops giving poe.  

 

But you  could  optionally use  power injectors for  a few  ports. Or ofc  use a bigger switch

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Kind of a big deal

Re: How many PoE ports are supported by MS128-8FP


@ww wrote:

The ms  can go up to 30w  per port. 


So to me this means, that each port can individually in theory go up to 30W, but just not all at the same time  😃

Nolan Herring | nolanwifi.com
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Kind of a big deal

Re: How many PoE ports are supported by MS128-8FP

I checked an MR52 on 26.7 with 60 clients connected and radio transmit power set on 16, it is using between 7.6 and 11.4W from an MS225

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Meraki Employee

Re: How many PoE ports are supported by MS128-8FP

Hi @angeloPV9 they will operate fine.  While the MR52 APs will want to see and negotiate 30W PoE+ power upon bootup, they will never draw more than 21 watts maximum, and in all likelihood they will average between 6 to 12 watts, but keep an eye on it to confirm.  

 

Go to the Switch > Switches page and click into the switch and click on the power tab.  You will see a "Consumption" section and a "Budgeted" section.  The number to worry about is the consumption. The budgeted number is just reflecting the total amount of theoretical power that could be consumed, as if every device pulled the full 15 or 30 watts of power it advertised via CDP/LLDP when it first negotiated.

 

See attached screen shot.  I have a compact MS220-8P switch running 7 PoE devices all the time (MV cameras and MR APs).  Looks at my "Budgeted" section, it says 140W/124W.  That's showing that the switch max budget is 124W of PoE power, and those 7 devices (at max power draw) would take 140W.  That's because 2 of my devices are an MV72 and an MR52 both of which negotiated 30W, and the other 5 devices negotiated 16W, so there's the 140W number.  It rounds 15.4W to 16W when doing this to err on the conservative side. 

 

But notice the consumption tends to hover around 41 to 45 watts.  Will that fluctuate?  Sure.  I don't watch it that closely, but I've never seen it over 60 watts, not even halfway to the max the switch can deliver.

 

Hope that helps!

MS220-8P-Power.jpg

View solution in original post

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Conversationalist

Re: How many PoE ports are supported by MS128-8FP

Hi Dave  yes I proposed this switch for design.

 

thank you and best regards!!

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