Many people access Internet via ADSL modems. And in you are one of them probably you know that modems loos their connectivity because of many reasons like instability in power supply and so on. All you need to do is to restart modem or go differently like Rajesh did. He decided to monitor internet connectivity with Atmega16 and Ethernet.
Once connectivity is lost, device simply disconnects primary ADSL modem and switches on secondary. This for sure gives more guarantee to sustain Internet working even if primary modem fails permanently. Atmega connects to hub by using RTL8019 ethernet chip and pings for connectivity. If five pings fail ADSLs are swapped.