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Message on WCS/NCS: Attempted to use IP Address assigned to another device



i have two WLCs AIR-CT5508-K9, monitored by WCS (in retiring stage) and NCS.

All APs are grouped in HREAP groups based on their locations. The wireless users are getting ip from a dhcp pool running on routers located at each site. All dhcp commands on every routers are the identical. Eg. rtr1, located on site 1 has ip pool for wifi users Rtr2 on site 2 has a ip pool for wifi users in range Occasionally i am getting bellow message when some wifi users are unable to connect. After creating a HREAP group and associating APs to correct group, this message stops showing for a while but now i am getting them again.

The temp solution to get it all running is to clear ip dhcp pool on router located at affected site.

Any suggestions for a better solution?



NCS has detected one or more alarms of category Security and severity Minor in Virtual Domain ROOT-DOMAIN

for the following items:

1. Message: Client '14:5a:05:6c:75:37 (' which was associated with interface '802.11b/g/n' of AP 'STV-AP-7198' is excluded. The reason code is '3(Attempted to use IP Address assigned to another device)'. - Controller Name: GEORGE-WLC


3 Replies 3

Justin Kurynny


If I understand what you’ve said, you are reusing the same network address space (192.168.8/24) in different segments of your internetwork. This runs counter to the most fundamental of practices in network design, wireless or no. Why are you recycling this same network at different locations, and is there any reason why you can’t put 192.168.8/24 at site 1 and 192.168.9/24 at site 2 (for example)?


Thanks for quick responce.

Well, you see, while using hreap you can have localy switched network so if you reuse subnet there should be no issue.

I used as an example, on my sites we use so .8 and .9 are all included.

Anyhow, do you have any other suggestions?


You are locally switching your networks, yes, but even without HREAP and WLCs, they are still connected networks in your overall topology, correct? I would never have site A with a given network that overlaps with a network in site B. With few exceptions, they should be completely separate, unique, non-overlapping network spaces. HREAP doesn’t even come into it.

The problem you’re likely having is that the WLC is seeing clients coming in from two different sites and because you are duplicating your configurations from site to site, the WLC sees duplicate IP assignment.

That said, you can try to turn off client IP address learning on the WLAN Advanced tab to see if that helps.


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