Tuesday, March 29, 2011

Cisco Aironet 1231 with PowerDsine midspan POE

Lesson of the week: the Aironet 1231 series access points use a messed-up version of pre-standard POE.

We use PowerDsine 6524 midspans, which support 802.3af and and pre-standard devices just fine. They power our Cisco IP phones, the 1100 series access points (pre-standard) and our brand-new Aruba APs. But not our 1231 APs.

Here's the trick: both 1130 and 1230 series APs use reverse-polarity power, compared to the POE standard. The 1130 series contains an internal diode-bridge, which swaps the polarity, if necessary, so they work just fine. The 1200 don't. So what you need is a custom patch cord, which crosses the 4-5 and 7-8 pairs (usually the blue and brown).