The IT folks at the coveted Princeton University have uncovered a problem related to Apple’s implementation of the DHCP protocol in iPhone OS 3.2 which runs the iPad. The first malfunction was reported on April 4 and over the last week, additional iPads malfunctioned in the same way. What is the root cause of iPad’s DHCP bug? Is there a workaround? If you want to know more about it, just read on.
What is DHCP?
For the unknown, DHCP (Dynamic Host Configuration Protocol) is a protocol that simplifies network management by assigning IP Addresses dynamically to new devices on the network. The IP Address is automatically assigned to new devices by the DHCP server for a certain duration known as the ‘lease’.
What is iPad’s DHCP Flaw?
It is reported that the iPad uses DHCP to obtain a lease, renews the lease zero or more times (as expected), but then continues using the IP address without renewing the lease further. The iPad allows the DHCP lease to expire, but it continues using the IP address after allowing the lease to expire which can potentially cause an “IP Address Conflict” on your network.
The Princeton Angle
Princeton has been able to reliably reproduce the issue by allowing the iPad to lock its screen before DHCP lease renewal time, and then allowing it remain in its “locked screen” state until the DHCP lease has expired. However, contrary to media reports and several rumors on the internet, Princeton has NOT banned use of the iPad on our campus network. In fact, the university has published a workaround to the issue which seems to work well in most cases.
Workarounds
While there is no software fix available for this issue as yet, several workarounds can help you avoid this issue. I found one such workaround on the Apple Discussions Forum. Then, there are at least three tried-and-tested workarounds suggested by the folks at Princeton. Each of these workarounds employ a simple trick - prevent the iPad’s screen from being locked while the device’s 802.11 wireless (“WiFi”) interface is on. Many users claim that switching your iPad’s WiFi on and off a couple times solved the issue for them.
Wrap-up
IMO, the DHCP flaw is not a major bug. Being a ‘Media Darling’ has its own pitfalls and that’s where the iPad is being pulled down. Even the slightest glitch in Apple iPad has been blown out of proportion and touted to be a show stopper flaw. The DHCP bug itself is pretty trivial and I expect a fix to be available soon. Till then, keep iPading and have fun!
Not a major bug? Pulled down? Out of proportion? Trivial? Have fun?
You must be an Apple Groupie. I have an Ipad but don’t have your limitations.
When the darn thing stops working on my network and can’t be started up again without rebooting the router and other silly measures, that’s a major flaw. My laptop doesn’t suffer from this problem, it’s about time Apple fixed it, this is becoming tiresome very quickly. Mine works for 4 or 5 days, then it’s crapola all the way unless I can persuade it to start over – that can take an hour or more. I don’t have that kind of time – Apple needs to improve their product testing to avoid this kind of nonsense.