Directly linked to Princeton problems

Faulty handling of DHCP (the Dynamic Host Configuration Protocol) is likely responsible for at least some of the iPad's Wi-Fi problems, one report suggests. To make use of a Wi-Fi connection, any device must normally obtain an IP address from a DHCP server. These IPs expire after a certain amount of time, and most devices will try to renew their addresses in advance.

Unlike the iPhone, the iPad keeps an active Wi-Fi connection while it is asleep; the tablet does not renew its address during this state however, and so it will continue to try using the same IP, even after waking up. This can create a conflict in which one or both of a pair of devices sharing the same address will be kicked offline.

The flaw is thought be responsible for Princeton University's connection problems, which have resulted in a temporary advisory against iPads there. 22 out of 41 iPads detected at Princeton have been recorded as causing problems, 8 of them to the extent that they have been banned from the school's network. For iPad owners in general the solution is said to involve turning off an iPad's Wi-Fi for a few seconds, reconfiguring DHCP to ping for duplicates, and/or giving an iPad a fixed address beyond DHCP's range. Extending DHCP lease time may at least alleviate difficulties.

by MacNN Staff