airtel do provide PPPOE type connection, I did this type of connection with Belkin N150 router (with modem only port)
@aby geek
you just need to peek into the Airtel's modems configuration. login using username admin and password is password , (if u r not able to login to modem, call customer care and they will provide u the password.)
usually the the PPPOE username will be STDcodewith phone number_area code @ airtelbroadband.in
and password will be 123456 (by default). but while installation it will be changed i think. if it is changed use any asterisk removal tool to view password.