G52CCN Computer Communications and Networks

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G52CCNComputer Communications and Networks

• Milena Radenkovic
• Room B47
• Email mvr_at_cs.nott.ac.uk

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Introduction

• Practical matters
• Module goals, structure and contents
• Initial introduction to some key ideas and issues

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Lectures

• Thursday 1500 1600
• Jubilee Campus, Exchange Building, LT2
• Friday 0900 1000
• Jubilee Campus, Exchange Building, LT2

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Related modules

• G53ACC - Advanced Computer Communications
• G5BIAW - The Internet and the World Wide Web

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Objectives

• To understand the basic principles of data
  communications and computer networks.
• To appreciate the complex trade-offs that are
  inherent in the design of networks.
• To provide a guided tour of network technologies
  from the lowest levels of data transmission up to
  network applications.
• To learn about current networking technologies,
  especially Internet protocols.

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Assessment

• Two hour written examination
• The style of question will be based upon those
  from previous years. Their content will of course
  be different.
• Last years exam paper is on sale in the bookshop
  and previous papers are in the library.
• No coursework

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Text books and notes

• My notes are available at
• http//www.cs.nott.ac.uk/mvr/ccn
• The core recommended course text is
• Computer Networks and Internets, Douglas E.
  Comer, Prentice Hall
• Supplementary texts are
• Tannenbaum, Computer Networks, Prentice Hall
• Halsall, Data and Computer Communications,
  Macmillan

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What is a computer network?

• An interconnection of autonomous computers (as
  opposed to communication between separate but
  interdependent parts of a single computer)

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Some goals of computer networks

• Access to remote resources
• Human communication
• Mobile computing
• Computing power through parallelism
• Optimising resources - load balancing
• Incremental growth of computer systems (reduced
  cost and risk)
• Increased robustness through graceful degradation

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Uses of computer networks

• Email, World Wide Web, Video Conferencing, File
  Transfer, Collaborative Virtual Environments,
  Remote control of robots and machines, Dial up
  databases, Webcasting, Distributed Programs,
  Hacking, Banking, Internet telephone

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Classifying networks

• By size
• Local area networks (LANs) versus Wide area
  networks (WANs)
• By connectivity
• Point to point versus broadcast networks
• By communication medium
• By mobility
• Fixed versus mobile

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Size - differences between local and wide area
networks

• Speed - bandwidth and latency
• Management
• Security
• Reliability
• Billing
• Heterogeneity (and standards)

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Connectivity - point to point networks
tree
star
irregular
mesh
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Connectivity - broadcast networks
wire
satellite/radio
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Medium - differences between communication media

• Speed - bandwidth and latency
• Range
• Sharing
• Topology
• Installation and maintenance costs
• Reliability

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Mobility - issues arising in mobile networks

• Mobile networking has emerged in the last decade.
  Introduces new issues of
• energy efficiency
• location and tracking
• semi-persistent connections
• complex administration and billing as devices and
  users move around the network

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Common issues in networking

• Addressing
• Routing
• Framing and encoding
• Error detection and correction
• Flow and congestion

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Module contents and structure
Part 4 applications
Part 3 internetworking
Part 2 packet transmission
Part 1 data transmission
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Part 1 data transmission

• Transmission media
• Local asynchronous communication (RS-232)
• Long distance communication (modems and carriers)

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Part 2 packet transmission

• Packets, frames and error detection
• Local area networks (LANs)
• Hardware addressing
• LAN wiring and physical topology
• Extending LANS Fiber Modems, repeaters, bridges
  and switches
• WAN Technologies and routing
• Network ownership and service paradigm
• Protocols and layering

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Part 3 internetworking

• Concepts, architecture and protocols
• IP addresses
• Binding protocol addresses (ARP)
• IP Datagrams and datagram forwarding
• IP encapsulations, fragmentation and reassembly
• The future of IP
• An error reporting mechanism (ICMP)
• TCP (reliable transport service)

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Part 4 Applications and Security

• Client-server interaction
• The socket interface
• Example applications

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Next Lecture

• Local Ansynchronous Communication and RS-232