EWC not acquiring IP

[abinaya.2.r]

Hello,

I have deployed EWC and around 20 AP are joined to the EWC. There was a scenario where there was a power outage. Post the power issue was resolved, All the Aps but three have re-joined the EWC.

Those three Aps were showing on the switch , but they were not acquiring the IP address  through DHCP. I thought to manually make those APs join to the EWC for which i connected the console.. Just as soon as the console was connected, the AP acquired the IP and joined the WLC. After connecting the console, I did not do any change.. This was weird and the same scenario happened with another AP. 

As it was a new site, I thought to repeat the power outage. Again the same three APs did not get the IP address and just by plugging in the console cable, it joined the EWC.

Has anyone faced this situation. Please share suggestion on how to proceed here whenever there is power issue at the site. 

[marce1000]

 - They might have had a temporary powering problem , for problem APs (remaining) on switches issue the command (on the switch) : show cdp neighbors detail 
                              Check if full AP model(s) and ip address allocated can be found , 

 M.

[abinaya.2.r]

Power drawn on all the connected Aps are 30W.

[marce1000]

 - And what about the other items I asked in my first reply : are they visible ?

 M.

[Rich R]

That sounds very suspicious to me!
What model of AP?
What version of software? (hint make sure it's up to date as per TAC recommended link below)
Have you checked earth/grounding of the switch(es) they're connected to? I'm inclined to think that sounds like an earth loop/current leakage problem.

Have you tried factory default reset on those APs?

In the latest code versions Cisco have changed the default console baud rate from 9600 to 115200 - apparently because 9600 slowed the boot time of the APs substantially!  Might be worth trying to change them to 115200 and see if that helps but I don't think that's the problem here.