The Grandma Story Not so long ago, in a country far, far away beyond the ocean, lived Grandma. Grandma had a granddaughter who lived on the other side of the ocean. They used to talk on the phone every day or so. One day the granddaughter asked her grandma for her special cake recipe. Grandma started explaining the long and complex recipe, but it was too long and complex to explain by phone so the granddaughter suggested a solution: "Connect your computer at home to the Internet! Use an ADSL connection. It is very quick and easy and uses the already existing phone infrastructure of public switched telephone network (PSTN) ." With the advice of her granddaughter and the important mission to deliver the recipe Grandma ordered the ADSL service from her local phone company, then called some ISPs (Internet Service Providers) to order connection to the Internet. "But why ADSL and which kind?" thought Grandma. Grandma discovered that different ISPs use different protocol stacks. We will cover two of the main protocol stacks that are being used. Click on the following links to answer Grandma's question.     Why ADSL?  The protocol stacks  References   This tutorial was constructed by Etay Shtrit and Maya Alperovitch as a final project in the course "Protocols and Computer Networks" at Tel-Aviv University, spring 2006.