802.af and cisco ilp

Answered Question
Dec 24th, 2008

hi every body!

If a switch and PoE-device support both 802.af and cisco ilp methid, which one will be used?

thanks a lot!

Correct Answer by viyuan700 about 8 years 1 month ago

But the question remain which method will be used if both switch and Ap can support 802.af and cisco ILp method

Output sh power inline when IP phone was detected. Cisco IP phone 7970 is connecetd to cisco unified 500 series.

USA_HQ#sh power inline

PowerSupply SlotNum. Maximum Allocated Status

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

INT-PS 0 80.000 15.400 PS GOOD

Interface Config Device Powered PowerAllocated

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

Fa0/1/0 auto Unknown Off 0.000 Watts

Fa0/1/1 auto Unknown Off 0.000 Watts

Fa0/1/2 auto Unknown Off 0.000 Watts

Fa0/1/3 auto Unknown Off 0.000 Watts

Fa0/1/4 auto Unknown Off 0.000 Watts

Fa0/1/5 auto Unknown Off 0.000 Watts

Fa0/1/6 auto Unknown Off 0.000 Watts

Fa0/1/7 auto IEEE-3 On 15.400 Watts ,

Output of sh power inline after some time

USA_HQ#sh power inline

PowerSupply SlotNum. Maximum Allocated Status

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

INT-PS 0 80.000 10.250 PS GOOD

Interface Config Device Powered PowerAllocated

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

Fa0/1/0 auto Unknown Off 0.000 Watts

Fa0/1/1 auto Unknown Off 0.000 Watts

Fa0/1/2 auto Unknown Off 0.000 Watts

Fa0/1/3 auto Unknown Off 0.000 Watts

Fa0/1/4 auto Unknown Off 0.000 Watts

Fa0/1/5 auto Unknown Off 0.000 Watts

Fa0/1/6 auto Unknown Off 0.000 Watts

Fa0/1/7 auto IEEE-3 On 10.250 Watts

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viyuan700 Wed, 12/24/2008 - 23:53

Cisco pioneered Inline Power over Ethernet with the release of Cisco Catalyst Inline Power in March of 2000 whereas 802.3af came much later. Cisco Inline Power is pre-standard so used only by cisco devices shipped before standard.

To preserve customer's existing investment in Cisco Inline Power, Cisco intends to implement Cisco Inline Power and IEEE inline power on future Cisco PDs and PSEs. This will enable existing Cisco Inline Power PDs and PSEs to be connected to future Cisco IEEE PSEs and PDs.

So if cisco is connected to cisco device , can use any but if connecetd to other vendorscan use only 802.3af.

sarahr202 Thu, 12/25/2008 - 18:56

Thanks for your reply!

Let say we have cisco switch and cisco'AP, both support 802.af and cisco ilp. Now which method will be used?

thanks a lot!

viyuan700 Thu, 12/25/2008 - 20:05

1. CDP not enabled

If a PD supports both IEEE 802.3af and Cisco pre-standard, the PD is detected as an IEEE device. PoE switches classify the PD at the detection stage and allocate a required power budget based on the IEEE class.

2. CDP is enabled

The phone is classified as a IEEE Class device when it first powers up, but after it powers up, CDP sets the desired power level .

Since all of this happens automatically, it is not possible to determine whether the IEEE standard or the pre-standard runs.

sarahr202 Fri, 12/26/2008 - 17:16

Well one way to find if PD is detected by 802.af standard or cisco ilp is to use the command" show power inline". If PD is detected by 802.af standard, we will find under the device field device type such as AIr-AP_1231_A-k9 and under the class field n/a.

But the PD is detected by ieee standard, then we will find " ieee PD" under the device field and any number from 0through 3 in class field.

So we can tell which method is used to detect and supply the power to PD.

But the question remain which method will be used if both switch and Ap can support 802.af and cisco ILp method.

thanks a lot!

Correct Answer
viyuan700 Fri, 12/26/2008 - 18:15

But the question remain which method will be used if both switch and Ap can support 802.af and cisco ILp method

Output sh power inline when IP phone was detected. Cisco IP phone 7970 is connecetd to cisco unified 500 series.

USA_HQ#sh power inline

PowerSupply SlotNum. Maximum Allocated Status

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

INT-PS 0 80.000 15.400 PS GOOD

Interface Config Device Powered PowerAllocated

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

Fa0/1/0 auto Unknown Off 0.000 Watts

Fa0/1/1 auto Unknown Off 0.000 Watts

Fa0/1/2 auto Unknown Off 0.000 Watts

Fa0/1/3 auto Unknown Off 0.000 Watts

Fa0/1/4 auto Unknown Off 0.000 Watts

Fa0/1/5 auto Unknown Off 0.000 Watts

Fa0/1/6 auto Unknown Off 0.000 Watts

Fa0/1/7 auto IEEE-3 On 15.400 Watts ,

Output of sh power inline after some time

USA_HQ#sh power inline

PowerSupply SlotNum. Maximum Allocated Status

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

INT-PS 0 80.000 10.250 PS GOOD

Interface Config Device Powered PowerAllocated

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

Fa0/1/0 auto Unknown Off 0.000 Watts

Fa0/1/1 auto Unknown Off 0.000 Watts

Fa0/1/2 auto Unknown Off 0.000 Watts

Fa0/1/3 auto Unknown Off 0.000 Watts

Fa0/1/4 auto Unknown Off 0.000 Watts

Fa0/1/5 auto Unknown Off 0.000 Watts

Fa0/1/6 auto Unknown Off 0.000 Watts

Fa0/1/7 auto IEEE-3 On 10.250 Watts

sarahr202 Fri, 12/26/2008 - 20:30

Thanks for your reply!

it appears from your post, on unified 500 platform, 802.3 af standard takes precedence over cisco ILp.

Is this same case for all platforms or it is different for different platforms?

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