G52CCNComputer Communications

and Networks

Milena RadenkovicMilena RadenkovicRoom: B47Room: B47

Email: mvr@cs.nott.ac.ukEmail: mvr@cs.nott.ac.uk

Introduction Practical mattersPractical matters Module goals, structure and contentsModule goals, structure and contents Initial introduction to some key ideas and Initial introduction to some key ideas and

issuesissues

Lectures

Monday,11:00Monday,11:00 Tuesday 12:00Tuesday 12:00

Related modules

G53ACC - Advanced Computer G53ACC - Advanced Computer CommunicationsCommunications

G5BIAW - The Internet and the World G5BIAW - The Internet and the World Wide WebWide Web

Objectives To understand the basic principles of data To understand the basic principles of data

communications and computer networks.communications and computer networks. To appreciate the complex trade-offs that are To appreciate the complex trade-offs that are

inherent in the design of networks.inherent in the design of networks. To provide a guided tour of network technologies To provide a guided tour of network technologies

from the lowest levels of data transmission up to from the lowest levels of data transmission up to network applications.network applications.

To learn about current networking technologies, To learn about current networking technologies, especially Internet protocols.especially Internet protocols.

Assessment Two hour written examination Two hour written examination

The style of question will be based upon those The style of question will be based upon those from previous years. Their content will of course from previous years. Their content will of course be different. be different.

Last year’s exam paper is on sale in the bookshop Last year’s exam paper is on sale in the bookshop and previous papers are in the library.and previous papers are in the library.

No courseworkNo coursework

Text books and notes My notes are available at:My notes are available at:

http://www.cs.nott.ac.uk/~mvr/ccnhttp://www.cs.nott.ac.uk/~mvr/ccn The core recommended course text is:The core recommended course text is:

Computer Networks and Internets, Douglas E. Comer, Computer Networks and Internets, Douglas E. Comer, Prentice HallPrentice Hall

Supplementary texts are:Supplementary texts are: Tannenbaum, Computer Networks, Prentice HallTannenbaum, Computer Networks, Prentice Hall Halsall, Data and Computer Communications, MacmillanHalsall, Data and Computer Communications, Macmillan

What is a computer network?

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

Some goals of computer networks Access to remote resourcesAccess to remote resources Human communicationHuman communication Mobile computingMobile computing Computing power through parallelismComputing power through parallelism Optimising resources - load balancingOptimising resources - load balancing Incremental growth of computer systems (reduced Incremental growth of computer systems (reduced

cost and risk)cost and risk) Increased robustness through graceful degradationIncreased robustness through graceful degradation

Uses of computer networks

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

Classifying networks By sizeBy size

Local area networks (LANs) versus Wide area Local area networks (LANs) versus Wide area networks (WANs)networks (WANs)

By connectivityBy connectivity Point to point versus broadcast networksPoint to point versus broadcast networks

By communication mediumBy communication medium By mobilityBy mobility

Fixed versus mobileFixed versus mobile

Size - differences between local and wide area networks ‘‘Speed’ - bandwidth and latencySpeed’ - bandwidth and latency ManagementManagement SecuritySecurity ReliabilityReliability BillingBilling Heterogeneity (and standards)Heterogeneity (and standards)

Connectivity - point to point networks

startree

irregularmesh

Connectivity - broadcast networks

satellite/radio wire

Medium - differences between communication media

‘‘Speed’ - bandwidth and latencySpeed’ - bandwidth and latency RangeRange SharingSharing TopologyTopology Installation and maintenance costsInstallation and maintenance costs ReliabilityReliability

Mobility - issues arising in mobile networks Mobile networking has emerged in the last Mobile networking has emerged in the last

decade. Introduces new issues of:decade. Introduces new issues of: energy efficiencyenergy efficiency location and trackinglocation and tracking semi-persistent connectionssemi-persistent connections complex administration and billing as complex administration and billing as

devices and users move around the devices and users move around the networknetwork

Common issues in networking

AddressingAddressing RoutingRouting Framing and encodingFraming and encoding Error detection and correctionError detection and correction Flow and congestionFlow and congestion

Module contents and structure

Part 1: data transmission

Part 2: packet transmission

Part 3: internetworking

Part 4: applications

Part 1: data transmission Transmission media; Transmission media; Local asynchronous communication (RS-232); Local asynchronous communication (RS-232); Long distance communication (modems and Long distance communication (modems and

carriers)carriers)

Part 2: packet transmission Packets, frames and error detectionPackets, frames and error detection Local area networks (LANs)Local area networks (LANs) Hardware addressingHardware addressing LAN wiring and physical topologyLAN wiring and physical topology Extending LANS: Fiber Modems, repeaters, Extending LANS: Fiber Modems, repeaters,

bridges and switches; bridges and switches; WAN Technologies and routingWAN Technologies and routing Network ownership and service paradigm Network ownership and service paradigm Protocols and layeringProtocols and layering

Part 3: internetworking Concepts, architecture and protocolsConcepts, architecture and protocols IP addressesIP addresses Binding protocol addresses (ARP)Binding protocol addresses (ARP) IP Datagrams and datagram forwardingIP Datagrams and datagram forwarding IP encapsulations, fragmentation and IP encapsulations, fragmentation and

reassemblyreassembly The future of IPThe future of IP An error reporting mechanism (ICMP)An error reporting mechanism (ICMP) TCP (reliable transport service)TCP (reliable transport service)

Part 4: applications

Client-server interactionClient-server interaction The socket interfaceThe socket interface Example applicationsExample applications

Next Lecture:

Transmission mediaTransmission media