In ubuntu 12.04, network configuration is attempted at the boot time and I often get notes like: "Waiting for network configuration" and later "Booting system without full network configuration". I want to stop this behaviour and would like to reach the log-in screen fast without any attempt to complete network configuration. After I log in, I want to add modem and use command like "pon dsl-provider" to connect to internet. How do I do that?

Will this change affect the way other processes take place?