A correct way to shutdown Cisco Autonomous AP

An interesting fact – powered over Ethernet autonomous Cisco access point continue to associate clients even if you shutdown the relevant switch port! I recently shutdown the switch port to which a spare access point has been connected, assuming it will stop providing PoE. Few days later my friend’s IT specialist reported their customers have connectivity problems when they approach that particular access point. He also asked if the blue light reflects a working condition. That knocked me down. How could it be powered on if I administratively disabled the switch port?!

I checked switchport status and it was in administratively shutdown state. I checked PoE status and found this switchport (although being shut!) continue to provide power. Huh?

WS-C3750-48PS-E#sh int statu | inc Port|Fa2/0/(45|46)
Port     Name    Status    Vlan  Duplex Speed Type
Fa2/0/45 AP1142N connected trunk a-full a-100 10/100BaseTX
Fa2/0/46 AP1142N disabled  1     auto   auto  10/100BaseTX
WS-C3750-48PS-E#sh power inline | inc Inter|Fa2/0/(45|46)
Interface Admin  Oper       Power   Device              Class Max
Fa2/0/45  auto   on         15.4    AIR-AP1142N-E-K9    3     15.4 
Fa2/0/46  auto   on         15.4    Ieee PD             3     15.4

How do you like that?

So, it turned out that instead of being shutdown this access point got its power over Ethernet, booted and due to its autonomous nature (had valid config!) were associating clients, but were unable to forward the traffic because switch port was in disabled (or admin shutdown) state.

Nice experience, indeed.

To fix it, I explicitly disabled PoE by applying “power inline never” to AP’s switchport. That solved issues with connectivity at once.

Update: This is IOS dependent! Unfortunately Cisco Bug Toolkit has no traces about such behavior.

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