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DHCP strange conflict


I have strange situation. I have one central switch cisco 3850 which works as DHCP server and wireless MC. Also there are 14 access switches also 3850 which work as wireless MAs. I have one SSID in which clients are working. There are Windows notebooks and smatphones connected to this SSID. So notebooks behave strangly. They get IP address from DHCP. Work about 30 minutes and then error "IP conflict with [MAC]" shows up((( Notebook changes its IP, then works about 30 min and again conflict and again change IP. The most strange is that MACs in errors are MACs from these 14 switches, of its physical ports!!! When I delete vlan for SSID from these switches but leave 2 switches with the vlan, notebooks work about 2 hours and then again conflict((( Could anyone propose a possible solution? I tried to change DHCP hardware to another router - no help. The same result.

I think that DHCP can not check IPs because of Windows firewalls. But it is very weak explanation. Moreover WiFi points and IP phones also get IPs from DHCP and no problems(((

Everyone's tags (1)
VIP Purple

Hi Pls provide the output of


Pls provide the output of below

3850(MC)#sh run | sec wlan

3850(MC)#sh run | in ip dhcp

3850(MC)#sh ip int bri | ex un

Same from a one of your MA

3850(MA)#sh run | sec wlan

3850(MA)#sh run | in ip dhcp

3850(MA)#sh ip int bri | ex un




*** Pls rate all useful responses ****

Thanks guys))) I figured out

Thanks guys))) I figured out what it was.

See CSCul01316 for  details. Try to upgrade software to 03.06


Hi,This message means more


This message means more than one computer is using the same IP address, which is resulting in a conflict.

In order to resolved this issue, u must make sure that each computer/ network device is assigned with an unique IP address and make sure your DHCP lease setting of DHCP server.