John Day, a protocol and ARPANET developer, answered this exact question most completely and wonderfully in his book "Patterns in Network Architecture: A Return

John Day, a protocol and ARPANET developer, answered this exact question most completely and wonderfully in his book "Patterns in Network Architecture: A Return to Fundamentals" [1]. [1] http://www.amazon.com/Patterns-Network-Architecture-Fundamentals-paperback/dp/0137063385 http://www.amazon.com/Patterns-Network-Architecture-Fundamen...