3-1 Introduction 3-2 Definition Architecture 3-3 Why have Architecture 3-10 3-5 Definition Architecture 3-6 The V.and X.standards 3-7 Advs and disadvs of standards 3-8 Communication Architecture 3-9 ISO Reference Model 3-4 Standards making org 3-11 Internet Architecture 3-12 Manufactures Architecture 3-13 A caveat about 3-14 Layered architecture