computer networks - 中国传媒大学 计算机学院 课程/课件...

Computer Networks Prof. Lin Weiguo

College of Computing Copyleft © 2003~2016 linwei@cuc.edu.cn

http://icourse.cuc.edu.cn/computernetworks/

Final Exam

l  4 parts 1.  True and False(20 points)

l  20 questions(1 point each) 2.  Multi Choices (20 points)

l  20 questions(1 point each) 3.  Terms and Concepts (40 points)

l  10 comprehensive questions(4 points each) 4.  Lab(20 points)

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Target of the exam

l  Grasp the basic concepts, principles and methods of computer networks.

l  Master computer network architecture and typical network protocol, understand the composition of a typical network equipments and features, understand the working principle of network equipment.

l  Be able to carry out the network system analysis, design and application by applying the basic concepts, principles and methods of computer networks.

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Quizzes for review

Note: ignore questions about email

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cs\networkstudents

Roadmap

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Introduction

Physical Layer

Data Link Layer

Transport Layer

Network Layer

Medium Access Sublayer

Application Layer

The Reference Model

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Chapter 1 Introduction 1.  Uses of computer networks

l  Computer networks concepts, Computation models

2.  Network Hardware l  Classifying networks

3.  Network Software l  Protocol Hierarchies and design issues

l  Protocols and Services

4.  Reference Models l  OSI and TCP/IP

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Chapter 2 PHY

l  Maximum Data Rate of A Channel l  The Nyquist equation l  Shannon's equation

l  Switching Technologies l  Circuit switching l  Message switching l  Packet switching

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Chapter 3 Data Link Layer l  Data Link Layer Design Issues

l  Functions and design l  Framing l  Error control and flow control

l  Elementary data link protocols l  ARQ: Automatic Repeat reQuest

l  Sliding window protocols l  Piggybacking, window size l  Go-Back-n l  Selective Repeat

l  Example Data Link Protocols l  HDLC and PPP

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Chapter 4 MAC sublayer l  The Channel Allocation Problem

l  Dynamic Channel Allocation l  Multiple Access Protocols

l  Pure/Slotted ALOHA l  CSMA/CD

l  Ethernet l  Ethernet Cabling and Topology l  Ethernet Frame Format l  The Binary Exponential Backoff Algorithm l  Switched Ethernet, Collision domain and broadcast domain

l  Data Link Layer Switching l  Bridges from 802.x to 802.y l  Local Internetworking: Backward learning algorithm l  Repeaters, Hubs, Bridges, Switches, Routers, Gateways l  Virtual LANs: IEEE 802,1Q

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TCP/IP packet in a Ethernet II Frame

Ethernet II with the ‘Preamble’ and ‘IFG (Inter-Frame Gap)’

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Chapter 5 Network Layer l  Network layer design issues

l  Store and Forward l  Implementation of Connectionless/Conn-Oriented Service l  Virtual-Circuit and Datagram Subnets

l  Routing algorithms l  Shortest Path Routing, Flooding l  Distance Vector Routing l  Link State Routing

l  Internetworking l  Tunneling, Fragmentation

l  The Networking layer in the internet l  IP packet format l  IP Addresses, subnetting and CIDR l  Internet Control Protocols: ARP, ICMP, DHCP l  OSPF and BGP

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Network Protocol Operations

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Protocol Data Unit Encapsulation

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Application

TCP

IP

Ethernet Driver

Ethernet Transmission

Line

Ethernet Header

IP Header

TCP Header

Application Data

Ethernet Trailer

14 Bytes 4 Bytes 20 Bytes 20 Bytes Variable Length 46 to 1500Bytes

IP Header

TCP Header

Application Data

TCP Header

Application Data

Application Header User Data

User Data

Application Message

TCP Segment

IP Packet (Datagram)

Ethernet Frame

Chapter 6 Transport Layer l  The Transport Service

l  Logical End-to-End Transport l  Essence of the Transport Layer

l  Elements of Transport Protocols l  Addressing: TSAP l  Connection Establishment: three way handshake l  Release: two army problem

l  The Internet Transport Protocols: UDP l  Port, UDP header and applications

l  The Internet Transport Protocols: TCP l  Key features: Seq. Number, TCP Segment, sliding window l  The TCP Segment Header Format l  TCP Connection Establishment/Release l  TCP Congestion Control and Slow Start Algorithm

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Chapter 7 Application Layer

l  DNS--- the Domain Name System l  Domain Name Resolving Process

l  Iterative/Recursive

l  the World Wide Web l  Browsing Steps l  Statelessness and Cookies l  HTTP Request – Response Model l  HTTP persistent connections

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