You question wasn't 100% clear so I'm assuming that you are only asking about how to download files. In that case Net::FTP is a good a starting point as any.
hie arhumanyu know i am supposed to write scripts that download confiiguration files of network devices eg routers using SNMP on Network on a daily basis,this is part of project,i don't if if there are librariies in perl which do this or predefined function to do this,