07-21-2008 10:30 AM - edited 07-03-2021 04:12 PM
We are thinking of migrating to 1250's to start preparing for 802.11n.
My questions are can you have a mixed environment with 1130's, 1231's, 1242's and 1250's. If so, are there any problems with roaming between different AP's? or Power requirements We have for the most part WS-C3750-48PS-S, WS-C3750G-48PS-S and 6500's
WS-X6148A-GE-45AF cards in the access closets.
Right now we have Cisco 7921 phones and Vocera badges on "B/G", wireless laptop carts on "A".
I am not concerned to much with increasing speed at this point I am more concerned with having a stable environment until we complete the migration.
07-21-2008 07:51 PM
The Cisco Aironet 1250 AP's, with both radio modules installed, requires a minimum of 18500 milli-watts of power. PoE switches can only go as far as 15400 milli-watt.
Cisco WS-C3560E-XXPDX-F and WS-C3750E-XXPDX-F (with version 12.2(44) IOS) will work (power inline port max nnnnn in interface configuration mode).
If you don't want to have additional financial outlay for extra switches, then use only one radio module.
07-22-2008 03:59 AM
You can also use the power injector, this will feed 56 volts to the AP over the ethernet
07-22-2008 05:37 AM
I am not sure I know what a power injector is
is it a software upgrade or a physical piece of hardware.
07-22-2008 05:36 AM
If we only use 1 radio module would I be able to support B/G/A until we upgrade to the newer switches.
07-22-2008 05:49 AM
No, the modules are either 2.4 and 5GHz. So you would have to decide between b/g or a. Keep in mind that Cisco discourages the use of 802.11n on the b/g side and makes it very difficult to enable on the b/g side.
As stated, you would need the 1252 power injectors or power supplies to power both radios. The power injectors can live in the wiring closet near the current switches and provide PoE to the APs.
We have 90+ 1252s running this way just fine, with the rest coming straight off the 3560-E switches.
07-22-2008 07:14 AM
Thank You for the Help!
07-22-2008 05:50 AM
Hi Peter,
The single Radio Module will not support b/g/a as b/g are supported on the 2.4GHz Module and "a" is on the 5GHz module.
As for the Power Injector, it is a Hardware device. This is the one for the 1250, AIR-PWRINJ4=Power Injector - 1250 Series
Cisco Aironet 1250 Series Ordering Guide
Hope this helps!
Rob
07-22-2008 07:14 AM
Thank You, it definately help me!
07-24-2008 11:30 AM
A Cisco Wireless SE told me that with the next version of WLC software we would be able to support 1252 AP's with 15 Mw and run both radios. Was he right?
07-25-2008 05:22 AM
That is the 1st time I have heard that.
I would guess that the power hardware on the 1250s would need to be able to accept the lower wattage and power both radios at the same time.
Also, I'm not sure what role the WLC has in actual PoE management, as it usually is controlled by the power subsystem in IOS. I had to upgrade my 3560-Es to 12.2.44 (SE-1) to make use of the enhanced PoE. Also, the 3560-E series have a larger power supply than the standard 3560s and are swappable.
That would be great if that is the case. Did he mention what the rev of code was? The latest is 5.151.0
07-25-2008 06:29 AM
I was trying to read through the release notes for 5.151.0 and I did see something about being able to configure the 1252 with a command for pre-standard PoE so they would work with 15.4 Mw, but not sure if I was reading it right.
07-25-2008 06:44 AM
from http://www.cisco.com/en/US/docs/wireless/controller/release/notes/crn511510.html#wp234040
"Configuring an Access Point's Prestandard Power Setting
An access point can be powered by a Cisco prestandard 15-watt switch with Power over Ethernet (PoE) by entering this command:
config ap power pre-standard {enable | disable} {all | Cisco_AP}
A Cisco prestandard 15-watt switch does not support intelligent power management (IPM) but does have sufficient power for a standard access point. The following Cisco prestandard 15-watt switches are available:
â¢AIR-WLC2106-K9
â¢WS-C3550, WS-C3560, WS-C3750
â¢C1880
â¢2600, 2610, 2611, 2621, 2650, 2651
â¢2610XM, 2611XM, 2621XM, 2650XM, 2651XM, 2691
â¢2811, 2821, 2851
â¢3631-telco, 3620, 3640, 3660
â¢3725, 3745
â¢3825, 3845
The enable version of this command is required for full functionality when the access point is powered by a Cisco prestandard 15-watt switch. It is safe to use if the access point is powered by either an IPM switch or a power injector or if the access point is not using one of the 15-watt switches listed above.
You might need this command if your radio operational status is "Down" when you expect it to be "Up." Enter the show msglog command to look for this error message, which indicates a PoE problem: "
Also from the same url:
Enhanced PoE switches-Enhanced PoE switches (such as the Cisco Catalyst 3750-E Series Switches) can be used with 1250 series access points to auto-negotiate a power level in excess of 15.4 W per port.
It is my understanding (correct me if I am wrong on this) that the switch power subsystem/supply can only dole out so much power either per port or overall regardless what the controller indicates.
Cisco power calc tool: http://tools.cisco.com/cpc/
(requires login)
07-25-2008 11:39 AM
Both modules will be supported at 802.3af power standards but you will be giving up some features like spatial radio streams. Also, bear in mind that the 1250 signals differently for power and may require a dongle to work with any pre standard 802.3at devices you might purchase.
10-16-2008 09:07 AM
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