ISC DHCPd runs out of IP addresses - "binding state abandoned;" in leases with no MAC address
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12-15-2024 09:42 AM
Hi,
We are operating around 100 units of indoor and outdoor Ruckus AP's with the help of ZD1200 in more than 40 buildings at our campus. The ISC DHCPd version 4.4.3 on Ubuntu LTS 24.04.1 is responsible for providing IP addresses to both the wired and wireless clients.
Each building is using its own /24 or /23 subnet. When setting up, we configured a single SSID (for roaming) for the Wifi, which can be accessed from everywhere. This worked successfully for a few years, but then we started observing that the DHCP was running out of IP addresses on the Wifi Subnet. Increasing the subnet range solved the problem temporarily, and after a certain period of time we had to clear the leases and/or restart the DHCP server. Than we started observing that the available IP addresses would exhaust in 5-10 minutes even after every reboot.
During the problem, we see plenty of leases with no MAC address, and the "dhcpd.leases" file is full of "binding state abandoned;" lines within the leases.
We have checked and made sure that there is only our DHCP server running within the subnet. We have also started monitoring the AP's with high, sometimes huge, number of client connections. We observed that, turning these AP's off would help us with the problem. Currently 6 of them are off and the IP usage of the subnet is around 16%.
Any idea how we could diagnose the problem ?
Regards.