台北科技大学：《计算机网络》（英文版） NP04 2 CONTENTS

The osi model and TCP/IP Protocol suite Computer Science and Information Engineering Spring 2004 Chuan-Ming liu CS旧E.NTUT. TAWAN

CSIE, NTUT, TAIWAN 1 The OSI Model and TCP/IP Protocol Suite Computer Science and Information Engineering Spring 2004 Chuan-Ming Liu

CONTENTS · THE OSI MODEI LAYERS IN THE OSI MODEL TCPIP PROTOCOL SUITE ADDRESSING ·TCP/ IP VERSIONS CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 2 CONTENTS • THE OSI MODEL • LAYERS IN THE OSI MODEL • TCP/IP PROTOCOL SUITE • ADDRESSING • TCP/IP VERSIONS

THE OSI MODEL CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 3 THE OSI MODEL 2.1

Layering Divide a task into pieces and then solve each piece independently (or nearly so) Establishing a well-defined interface between layers makes porting easier Major advantages ◆ Code reuse ◆ Extensibility CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 4 Layering • Divide a task into pieces and then solve each piece independently (or nearly so). • Establishing a well-defined interface between layers makes porting easier. • Major Advantages: Code Reuse Extensibility

Layering Example: Federal Express Letter in envelope, address on outside FedX guy adds addressing information barcode Local office drives to airport and delivers to hub Sent via airplane to nearest city. Delivered to right office Delivered to right person CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 5 Layering Example: Federal Express • Letter in envelope, address on outside • FedX guy adds addressing information, barcode. • Local office drives to airport and delivers to hub. • Sent via airplane to nearest city. • Delivered to right office • Delivered to right person

FedX Layers Letter Addressed Envelope 国厦啡 mmn Ie Letter Addressed Envelope CSIE NTUT

CSIE, NTUT, TAIWAN 6 Letter FedX Layers Letter Addressed Envelope Addressed Envelope

Layered Software Systems Network software Operating systems Windowing systems CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 7 Layered Software Systems • Network software • Operating systems • Windowing systems

Unix/Linux is a Layered system Applications Libraries System Calls Kernel

CSIE, NTUT, TAIWAN 8 Unix/Linux is a Layered System Applications Libraries System Calls Kernel

OSI Model Although the Osi model is a just a model (not a specification), it is generally regarded as the most complete model(as well it should be nearly all of the popular network protocol suites in use today were developed before the OsI model was defined) CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 9 OSI Model Although the OSI model is a just a model (not a specification), it is generally regarded as the most complete model (as well it should be - nearly all of the popular network protocol suites in use today were developed before the OSI model was defined)

Note ISO is the organization. oLis the model CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 10 ISO is the organization. OSI is the model