DHCP server balancing issue

[de Brouwer Tom (ST-CO/ENG5.1)]

Hi,

I'm experiencing some issues with my redundant ISC DHCP setup, I'm using version "dhcp-4.1-ESV-R4", compiled with "--enable-delayed-ack".

The issue I'm experiencing is that the balancing suddenly stops and never restores correctly, and a such only half of my clients get IP addresses assigned. I debugged this currently to the stage that one of the DHCP servers get's into the "communications-interrupted" state and therefore does not allow to balance the pool (I think). Sometimes it takes 2 weeks, sometime a few days before the servers gets into this state. Restarting dhcpd resolves this issue.

In the slave log, I get the warning "Got POOLREQ, answering negatively!  Peer may be out of leases or database inconsistent."

In the master log, I get the warning "pool response: 0 leases"

Under normal operations I see the master logging "balancing pool 8fe8f68 192.168.6.0/24  total 241  free 20  backup 81  lts -30  max-own (+/-)10" every hour, once I start experiencing this issue the log is changed into "balancing pool 8fe8f68 192.168.6.0/24  total 241  free 19  backup 81  lts -31  max-own (+/-)10  (requesting peer rebalance!)" Which I think means it gets to a critical available lease threshold.

What could be causing this issue? I couldn't find anything in the release notes of dhcp-4.1-ESV-R11 which explicitly points to this issue, so I'm not sure whether upgrading makes sense.

Thanks,

Tom

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