Modern DSL gateways often integrate routing and other functionality. Their initialization is very similar to a PC boot up. The system image is loaded from the flash storage; the system boots, synchronizes the DSL connection and finally establishes the internet IP services and connection between the local network and the service provider, using protocols such as DHCP or PPPoE. According to "Implementation and Applications of DSL Technology" (2007), the PPPoE method far outweighed DHCP in terms of deployment on DSLs, and PAP was the predominant form of subscriber authentication used in such circumstances. The system image can usually be updated to correct bugs, or to add new functionality.