Is there a Restriction in the amount of ip phone when using Class 3 (15.4W)

Unanswered Question
Oct 23rd, 2008


I need to connect an cisco ip Phone on a 3560 switch or 3750 with POE

Does anyone know if there is a restriction in the amount of phones you can connect when using the max power (class 3)

• IEEE 802.3af Device - Class 0 (15.4W)

• IEEE 802.3af Device - Class 1 (4W)

• IEEE 802.3af Device - Class 2 (7W)

• IEEE 802.3af Device - Class 3 (15.4W)

Thank you


I have this problem too.
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Overall Rating: 4.5 (4 ratings)
CHRIS CHARLEBOIS Thu, 10/23/2008 - 14:02

Looks like the 3560 and 3750 with PoE can support up to 24 ports at 15.4W or up to 48 at 7.3. The 3560-E and 3750-E can support 48 ports at 15.4W.

Sushil Kumar Katre Fri, 10/24/2008 - 00:42

Hi Ishai,

As Chris pointed correctly, 3560 and 3750 switches can support 15.4W on 24 ports or 7.7W on all 48 ports or a combination of 15.4W and 7.7W on all the interfaces.

Thr overall capacity of these switches is 370W. So if you add the power consumed on all the interfaces it should not be more than 370W when you are using a combination of 15.4W and 7.7W.

This question is answered in the following Q&A Question number 4 -

-> Sushil

rob.huffman Fri, 10/24/2008 - 04:41

Hi Ishai,

Just wanted to add this little note to the great info from Chris and Sushil (+5 points each guys for your stellar info :)

This tool "The Cisco Power Calculator" is really great and will take all the guesswork out of determining these type of requirements;

Hope this helps!



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