Cisco 1221 AP to IP phone phone power issue

I am are working on a solution for a county fire service. They recently have had a sizeable Cisco IP phone rollout, over their ~30 stations.

The next stage is to install phones in their Breathing Apparratus rooms, which we can't hardwire cat-5 in to. So, we're testing a solution, using Cisco 1231G AP's, the remote in workgroup bridge mode, to link via a wireless bridge, back to the LAN. We then plug a Cisco IP phone eg: 7912G, in via cross-over to the remote AP.

The problem is when I plug a phone in to the Ethernet of the remote AP via cross-over cable, the phone switches off. This works fine conecting up my laptop. If I install a switch between the two devices, plug AP and phone in to that - it works. Because of the environement in the fire stations, we don't want to install a switch, we would like to use the cross-over direct in to the phone. (if possible!) I am assuming there is some kind of Cisco proprietary Inline power issue going on here, and the phone switches itself off, expecting to be powered via Inline?

Customer doesn't want to use a wireless Cisco 7920 - they'd like a desktop phone, so we're stuck with a wireless workgroup bridge. We could use another AP, without Cisco Inline, but the 1200 is rugged, and deisgned for that envirnment, much preferred choice.

How can we get the phone working with the access point, without the use of a switch?

Any help here would be greatfully appreciated.

Stuart.

Reply to
Emlynfluff
Loading thread data ...

Hi Stuart,

The AP1200 does not *supply* Power over Ethernet (although it can

*consume* PoE. So if you're trying to power your 7912G from the AP, this can't work.

So you would need to power your phone from a brick plugged into an AC power source (or some other how supply the phone with the 48VDC that it requires.)

Regards,

Aaron

Reply to
Aaron Leonard

Hi Araon, cheers for the reply.

Yep, I understand the devices are clients receiving Inline power.

The access point has its power supplied by the PSU. The phone is also using an external power adapter (cube) to supply its power. I connect external the power to the phone, it boots up, then connect the cross-over cable in to the phone-AP, the phone switches itself off. I believe the phone is doing some sort of Inline power negotiation, and since the AP also supports this (as a client), maybe they're getting confused? The phone could think that the AP can supply Inline power, so the phone swiches off external PSU, and chooses ILP as a preferred souce? I can't force the phone to use external power only, ignoring ILP. I can't disable Inline power on the AP..

Any ideas how to work round this? I know sticking a switch in between the two devices works. I snipped the spare pins in the Ethernet cross-over cable, 4,5,7 & 8, but then read Inline power uses the same as Ethernet - damn it! ;) The spare cat-5 pins are used for the IEEE standard 802.3af, not Cisco proprietary ILP.

Stuart.

Reply to
Emlynfluff

~ On 14 Feb, 18:24, Aaron Leonard wrote: ~ > Hi Stuart, ~ >

~ > The AP1200 does not *supply* Power over Ethernet (although it can ~ > *consume* PoE. So if you're trying to power your 7912G from the ~ > AP, this can't work. ~ >

~ > So you would need to power your phone from a brick plugged into an ~ > AC power source (or some other how supply the phone with the 48VDC ~ > that it requires.) ~ >

~ > Regards, ~ >

~ > Aaron ~ ~ Hi Araon, cheers for the reply. ~ ~ Yep, I understand the devices are clients receiving Inline power.

~ The access point has its power supplied by the PSU. ~ The phone is also using an external power adapter (cube) to supply its ~ power. I connect external the power to the phone, it boots up, then ~ connect the cross-over cable in to the phone-AP, the phone switches ~ itself off.

Ah, ok, that was the OTHER possible interpretation of your setup that I entertained from your previous posting. I chose to assume the one that had the easier explanation :)

So, given this report, my guess is that the phone is being confused by the CDP from the AP. So I would turn off CDP on the FastEthernet0:

int faste0 no cdp enable

Does this help?

Aaron

Reply to
Aaron Leonard

No joy there, I'm afraid. I've done a "no cdp run" on the AP, phone still switches itself off when I plug in the cross-over, and the phone is powered via PSU.

I read that CDP is used after the device has recieved power, so it can suss out the devices actual power requirements, rather than wasting some of its limited power budget on a single device.

Thanks for trying, I guess we may have to put a swtch between the 2 devices, which is a shame.

Reply to
Emlynfluff

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.