Does any DHCP platform clear the conflicts periodically?

[chelenegro]

I had been assuming that when a router (Cisco) detects a DHCP address conflict, it would at some point reassign the address. Unfortunately, I've discovered that that's wrong and if an address conflict is detected, the address is removed from the pool, and the address will not be assigned until an administrator resolves the conflict.

We have routers where a significant portion of their available address pool is taken by conflicts. I can't find any reference in Cisco documentation or in this forum mail threads to a "timeout" feature of some sort to automatically clear these conflicts. Perhaps disabling conflict logging would accomplish the same thing, though for troubleshooting purposes it's nice to know if there are excessive conflicts. It occurs to me that we need a process to review and remove these manually if we can't get a way to do it automatically. The result where sites run routers for long periods of time between reboots will be service calls to us because the site runs out of available address space.

Any idea is appreciated.

Jose Luis Martin Cenjor - CCNP, PMP
HP Managed Services - WAN

 

[mojo31]

Would the router even care about an IP conflict? Apart from a bit of a messed up arp cache, surely the router wouldnt care? If you are using MS DHCP there is collision detection built in (more in 2K, 2k3) to prevent IP clashes. Sorry I may be way off here.

 

[chelenegro]

mojo31, indeed it cares, to the point that I mention above. If a site doesn't get rebooted during certain period of time (usually months) and eventually ip conflicts start to flourish (eg. mass migration of PC workstations at site and high DHCP release/renew traffic) then it might eventually happen that the router acting as DHCP Server run out of IP addresses. (This last example is from my own experience)

Jose Luis Martin Cenjor - CCNP, PMP
HP Managed Services - WAN