The internal DHCP server was introduced initially for branch offices where an external DHCP server is not available. It is designed to support a small wireless network with less than ten APs that are on the same subnet. The internal server provides IP addresses to wireless clients, direct-connect APs, appliance-mode APs on the management interface, and DHCP requests that are relayed from APs. It is not a full-blown general purpose DHCP server. It only supports limited functionality and will not scale in a larger deployment.
However, 4000 clients could get an ip from internal pool on 184.108.40.206.
I would recommend that you use external DHCP server. Internal DHCP is designed to help but not to fully replace external DHCP servers in enterprise.
Besides, the version you are using is old. You can upgrade to 220.127.116.11 which should handle system resources more efficently and hence mitigate your problem.
You can also upgrade to some 7.0.x versions. (avoid 18.104.22.168 though). 7.0 has more new features.
I suggest that you upgrade and if the problem is still exist then you use external DHCP.
Because of your current problem; enabling debugs on your WLC would possibly overwhelm the memory and CPU more and make the WLC more prone to crash again.
You can collect sniffer traces on the WLC port if you'd like which is better than enabling debugs.
You can restrict the debugs to be with one client only (debug mac addr ) then follow the debugs you'd like. However, debuggin only one client will not give you statistics about dhcp requests received by WLC. it only shows you dhcp process of one client.
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Transferring Crash file from standby:
Login to the Active WLC in HA.
(Cisco Controller) >transfer upload datatype crash
(Cisco Controller) >transfer upload filename <Desired filename>
(Cisco Controller) >transfer up...
This is the start of a display filter cross reference between Wireshark and OmniPeek.
The 1st installment is a table of advanced filters. More filters will be added as time allows.
It is a living doc, so check back for changes every so often
Please feel ...
I have created a Powershell script to automatically add a Wireless Guest User on Cisco WLCs. (tested on 2500 Series)
The script should be completely self explanatory.
Powershell SNMP Module (Install-Module -Name SNMP)
SNMP Write Access to...