Duplicate IP's on a Mac

[Devmike06]

Good morning All,

I have an issue that I haven't been able to resolve as of late. We have a switch that is giving out duplicate IP's after servers reboot and we've been able to resolve them with the gratuitous arp registry addition, but I am having issues resolving this with a Mac. 

How would I go about fixing duplicate IP's due to gratuitous arp on a Mac device? I tried doing some research, but it's tough due to Mac devices and MAC address's. 

[Devmike06]

Any possible assistance with this one?

[Mark Malone]

Hi
do you mean your seeing same ips in logs based against the same MAC address ?
someone may have set a static IP in TCP/IP on one of the ports and DHCP may have also given it out , can you trace the macs back to each port and check the local PC/server NIC setup

[Devmike06]

No, that's not what's going on. A system that is plugged into this switch will have it's IP working fine until it is restarted. Once it's restarted, the machine will say it can't use that IP address because it's already taken. We've had to add the registry edit to our windows machines to fix this issue and they are working "fine" now. Only issue is I can't make that registry edit on mac's, so I don't really know what to do for mac systems that lose their IP's. Everytime I try to log onto this mac that I set up as a test, after this issue started occurring, it states that the static IP that I have given it, is already taken by another device, but there is no other device on the switch that has this IP.

[Mark Malone]

Ok dont know anything about MACs to be honest from that side so maybe someone else who works on them can jump in

it sounds as though switch IOS may be at fault too as its effecting windows as well , have you debugged the DHCP detail to see who is at fault if the switch or PC is not releasing the ips , maybe the software on the switch is at fault and an upgrade will fix it , rather than touching every connected PC/MAC

[Devmike06]

Yeah, we're pretty sure that the switch is at fault here, as it is quite old. The issue I have with that, is that they do not want to upgrade the switch to a newer model, which is making me look for this work around to solve the issue that it's having.