《信息技术战略管理》Chapter 6 Networks and Telecommunications

Chapter 6 Networks and Telecommunications The Strategic Management of Information echnology

Chapter 6 Networks and Telecommunications The Strategic Management of Information Technology

Transaction Processing System Input Process Output Systems Development Communication Information

Transaction Processing System Input Process Output Information Communication Systems Development

Local Area networks

Local Area Networks

Local Area networks A Definition Provides access to shared resources such as printers, data, and applications Increases controllability and consistency in applications and data Increases access to shared applications and databases in large computers with many users Provides a vehicle for electronic mail Shares access to external resources through communication lines

Local Area Networks: A Definition Provides access to shared resources such as printers, data, and applications Increases controllability and consistency in applications and data Increases access to shared applications and databases in large computers with many users Provides a vehicle for electronic mail Shares access to external resources through communication lines

Local Area networks Reason Performance Change Management Systems Management Network Management Direct communication Ease in Installation and maintenance

Local Area Networks: Reason Performance Change Management Systems Management Network Management Direct Communication Ease in Installation and Maintenance

Network protocols 1. Physical Layer Interfaces between Network medium and network drives Defines electrical and mechanical characteristics of network Bad Plug

Network Protocols 1. Physical Layer – Interfaces between Network Medium and Network Drives – Defines Electrical and Mechanical Characteristics of Network – Bad Plug

Network protocols 2. Logical Link Layer Frames Packets Controls Physical layer data flow Data collision 3. Network Layer Addresses and Routes Packets Handles fragmentation and reassembly of data Broadcast storm 4. Transport Layer Manages Network Layer Connections Provides Reliable Packet Delivery Mechanism Multiple ACKs

Network Protocols 2. Logical Link Layer – Frames Packets – Controls Physical Layer Data Flow – Data Collision 3. Network Layer – Addresses and Routes Packets – Handles Fragmentation and Reassembly of Data – Broadcast Storm 4. Transport Layer – Manages Network Layer Connections – Provides Reliable Packet Delivery Mechanism – Multiple ACKS

Network protocols 5. Session Layer Provides Remote Procedure Call Support Reports Lower-Layer Errors Protocol error 6. Presentation Layer Specifies Architecture-Independent data transfer Format Encodes and Decodes Data; Encrypts and Decrypts Data Compresses Data Misdirected data 7. Application Layer Provides Interface to End-User Processes Provides Standardized Services to Applications Incompatible Software

Network Protocols 5. Session Layer – Provides Remote Procedure Call Support – Reports Lower-Layer Errors – Protocol Error 6. Presentation Layer – Specifies Architecture-Independent Data Transfer Format – Encodes and Decodes Data; Encrypts and Decrypts Data; Compresses Data – Misdirected Data 7. Application Layer – Provides Interface to End-User Processes – Provides Standardized Services to Applications – Incompatible Software

Communication according to the Open System Interconnection Reference Model Application Layer 76543 Presentation Layer Session layer Transport layer Network layer Data Link layer Physical layer

Communication according to the Open System Interconnection Reference Model 1 2 3 4 5 6 7 Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer

Physical Layer Hardware Description The interface to the physical cable medium 76543 described: layout of connectors, signals on each connector, voltage levels The physical connection to the netw connections are established and maintained and howlerror conditions in data medium are handed Physical layer

Physical Layer 1 2 3 4 5 6 7 Physical Layer Hardware Description: The interface to the physical cable medium is described; layout of connectors, signals on each connector, voltage levels. The physical connection to the network, how connections are established and maintained, and how error conditions in data medium are handled