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Kudos0

IP Conflicts

I'm having problems with devices getting duplicate IPs.  I was a problem with my IPhone not showing Norton Security installed or being discovered correctly.  It turns out that the phone had an IP assigned that was the same from a device that was previously on the network.  I reset my Core and removed all devices and then added my IPhone and it was discovered correctly and it showed Norton Security installed.  All the other devices installed correctly until I added my wife IPhone joined the network again.  One of the devices that I previously had on the network was on Previously on your network and when I added the IPhone it obtained the same IP as the device that was previously on.  This caused it to not discover the iPhone correctly and it did not show that Norton Security was installed, before I reset the Core this is the only IPhone that said that Norton Security was installed.  There is a problem with DHCP duplicating IPs with IP addresses on Previously on the network and preventing devices from being identified correctly.

Replies

Kudos0

Re: IP Conflicts

Anyone else having this problem?

Kudos0

Re: IP Conflicts

Apple IOS devices tend to assume that a DHCP lease is an iron clad promise. They assume they still have the lease even if they've lost the connection and then re-connected. This often leads to DHCP sync issue (IP conflicts are the most notable).

If the Norton router was reset or rebooted or removed the DHCP leases (disconnecting the Apple devices in the process), when the Apple devices reconnect they don't ask for a new lease like they should, they just assume they have the old (likely forgotten and given to another device) lease.

Kudos0

Re: IP Conflicts

Apple IOS devices are extremely hard to renew their DHCP I agree.  My problem was a little different.   I reset the router and erased all the devices and added them back except 1 IPhone.   I had a smart tv that I added to the network and then was moved to the previously connected group, when I later added the IPhone it duplicated the ip address from the smart tv so it couldn't be identified.  Reconnected the smart tv it reassigned itself a new ip and then the iPhone was identified after a while.

Kudos0

Re: IP Conflicts

MannyT:

Apple IOS devices are extremely hard to renew their DHCP I agree.  My problem was a little different.   I reset the router and erased all the devices and added them back except 1 IPhone.   I had a smart tv that I added to the network and then was moved to the previously connected group, when I later added the IPhone it duplicated the ip address from the smart tv so it couldn't be identified.  Reconnected the smart tv it reassigned itself a new ip and then the iPhone was identified after a while.

Sounds like the exact problem I described. The Apple device assumed it still had a lease on the last IP assigned to it by the router. The router was off, then reset. The Apple device assumed it still had a lease from the device it was not connected to for a while -- it was wrong.

Does the new Norton router send DHCP NAKs?

Kudos0

Re: IP Conflicts

Not quite this was a completely a new network.  Since it was a new network(different name) DHCP should have a assigned a different IP to the Apple device because the device was never on the network and it didn't have a lease .   Even if the IOS device would have had a lease previously on the network it would have chosen that IP not the one for the smart tv.  This from my experience from running a network (I wasn't Microsoft Certified) for a few years and having to delete devices that were no longer on the network and running out of dhcp leases.  DHCP should never repeat IP addresses on less one is static and the address was not reserved or out of the address pool for DHCP.  Since the Core router doesn't allow static addresses this shouldn't happen in my opinion.

Kudos0

Re: IP Conflicts

MannyT:

Not quite this was a completely a new network.  Since it was a new network(different name) DHCP should have a assigned a different IP to the Apple device because the device was never on the network and it didn't have a lease .   Even if the IOS device would have had a lease previously on the network it would have chosen that IP not the one for the smart tv.  This from my experience from running a network (I wasn't Microsoft Certified) for a few years and having to delete devices that were no longer on the network and running out of dhcp leases.  DHCP should never repeat IP addresses on less one is static and the address was not reserved or out of the address pool for DHCP.  Since the Core router doesn't allow static addresses this shouldn't happen in my opinion.

The apple device "detected" (read as: "guessed") that it was the same network because the MAC address of the Norton router hadn't changed. It then assumed that it could keep the same IP address. It did this because if it was right it would reconnect 2-8 seconds faster.

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