Transcript Transmission Media

G52CCN
Computer Communications
and Networks
Milena Radenkovic
Room: B47
Email: [email protected]
Introduction
Practical matters
 Module goals, structure and contents
 Initial introduction to some key ideas and
issues
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Lectures
Monday,11:00
 Tuesday 12:00
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Related modules
G53ACC - Advanced Computer
Communications
 G5BIAW - The Internet and the World
Wide Web
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Objectives
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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.
Assessment
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Two hour written examination
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The style of question will be based upon those
from previous years. Their content will of course
be different.
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Last year’s 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
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My notes are available at:
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The core recommended course text is:
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http://www.cs.nott.ac.uk/~mvr/ccn
Computer Networks and Internets, Douglas E.
Comer, Prentice Hall
Supplementary texts are:
 Tannenbaum, Computer Networks, Prentice Hall
 Halsall, Data and Computer Communications,
Macmillan
What is a computer network?
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An interconnection of autonomous
computers (as opposed to communication
between separate but interdependent parts
of a single computer)
Some goals of computer networks
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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
Uses of computer networks
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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
Classifying networks
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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
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
Connectivity - broadcast
networks
satellite/radio
wire
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
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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
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
Part 1: data transmission
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Transmission media;
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Local asynchronous communication (RS-232);
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Long distance communication (modems and
carriers)
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
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Client-server interaction
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The socket interface
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Example applications
Next Lecture:
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