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Mark Gleeson

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Diploma in Health Informatics Networks Mark Gleeson gleesoma_at_cs.tcd.ie (01) 896 2666 Distributed Systems Group, Trinity College, Dublin 14.02.2009 – PowerPoint PPT presentation

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Title: Mark Gleeson


1
Diploma in Health Informatics Networks
  • Mark Gleeson
  • gleesoma_at_cs.tcd.ie
  • (01) 896 2666
  • Distributed Systems Group,
  • Trinity College, Dublin
  • 14.02.2009

2
Objectives
  • Understand some network terminology- enough to be
    able to read further on the topic.
  • Understand some issues of network design.
  • Issues concerning application of networking to
    health.
  • Emphasis on practical aspects

3
Introduction to Networks
  1. Introduction
  2. Network characteristics
  3. Network Software
  4. Network Hardware
  5. Security
  6. Internet and the World Wide Web
  7. Telemedicine

4
Section 1 Introduction - Network Basics
  • What is a network?
  • What does it do?
  • How useful is the network
  • Various key attributes

5
Introduction (1/2)
  • In the 20th Century key technologies were
    employed for information gathering, processing
    and distribution.
  • Some developments include
  • worldwide telephone networks
  • the invention of television and radio
  • the unprecedented growth of the computer industry
  • launching of communication satellites
  • These areas are converging. The convergence of
    computers and communications is very significant.

6
Introduction (2/2)
  • Initially computers were highly centralized,
    usually within a single room. Computers were
    physically large.
  • The development and advances made in the computer
    industry are huge.
  • Now lots of small independent computers
    communicating to do a job. These are called
    Computer Networks

7
What is a Computer Network? (1/2)
  • An interconnected collection of computers which
    are
  • Co-operative
  • Co-operative action is required between the
    components
  • Autonomous
  • All components are capable of independent action
  • Any resource is capable of refusing requests
  • Mutually Suspicious
  • Components verify requests

8
What is a Computer Network? (2/2)
  • Any computer connected to a network is known as a
    host.
  • Local host
  • Your own computer
  • Remote host
  • The computer elsewhere you are in contact with
  • There are hardware and software aspects to
    computer networks

9
(Digital) Bandwidth
  • The amount of data per second a communications
    link can carry
  • Typically referred to in bits per second
  • Note 1 byte 8 bits
  • The actual amount of useful data you can send
    will be less than the actual capacity
  • Overheads for
  • Addressing
  • Routing
  • Error detection
  • Medium access

10
Latency / Delay
  • Measure of the delay from sending a piece of data
    or request until it is processed at the
    destination
  • Exceptionally important for
  • Video and audio
  • Voice over IP, Skype, Video conferencing
  • Interactive systems
  • Inquiry based systems patent records
  • Booking systems
  • Needs careful investigation to determine the weak
    points
  • Is it the network or the computer?

11
More Terminology
  • Attenuation
  • Measure of how much a signal degrades per
    distance in a certain medium
  • Different cable types have difference values
  • Attenuation limits the distance you can
    communicate over
  • Electro Magnetic Interference - EMI
  • Electrical noise artificially generated
  • Watch out for high powered electrical equipment
  • MRI machines, Trams, Electric trains, Microwaves
  • Of particular concern in wireless networks
  • Microwaves operate at a frequency used by
    802.11b/g

12
Section 2 - Network characteristics
  • What Are Networks
  • Network Types and Topologies
  • Communication concepts
  • Basic Message Types

13
What are Networks?
  • Tanenbaums definition
  • "A network is an interconnected collection of
    autonomous computers"

14
Types of Networks
  • Bus-based networks
  • Original Ethernet (802.3)
  • Star-based networks
  • Switched (Modern) Ethernet (802.3ab)
  • Ring-based networks
  • FDDI
  • Token Ring (802.5)
  • Wireless networks
  • WiFi (802.11a/b/g/n), Bluetooth, Hyperlan IrDA,
    WiMax, GSM, EDGE,3G

15
LAN Topologies
16
Types of Networks
  • Classification based on diameter

1 m System
10 m Room
100 m Building
1 km Campus
10 km City
100 km Country
1,000 km Continent
10,000 km Planet
Multi-processor
PAN (Personal Area Networks)
LAN (Local Area Networks)
MAN (Metropolitan Area Networks)
WAN (Wide Area Networks)
The Internet
17
Local-Area Networks (LANs)
Figure is courtesy of B. Forouzan
18
Wide-Area Networks (WANs)
  • Latency
  • Administration/Jurisdiction

Figure is courtesy of B. Forouzan
19
Simplex
Figure is courtesy of B. Forouzan
20
Duplex
Half-Duplex
Full-Duplex
Figure is courtesy of B. Forouzan
21
Point-to-Point Multipoint
Figure is courtesy of B. Forouzan
22
Basic Message Types
  • Three basic message types
  • 1. Unicast - one sender to one receiver

Sender
Receiver
23
Basic Message Types
  • Three basic message types
  • 1. Unicast - one sender and one receiver
  • 2. Broadcast - one sender, everybody receives
  • Broadcast addresses
  • network ID
  • all bits of host ID set
  • e.g. 134.226.255.255

Sender
24
Basic Message Types
  • Three basic message types
  • Unicast - one sender and one receive
  • Broadcast - one sender, everybody receives
  • Multicast - one sender and a group of receivers

Sender
Receivers
25
Section 3 - Network Software
  • Originally hardware matters were the main focus
    when building networks the software was an
    afterthought.
  • Key Network Software concepts
  • Layers
  • Protocols
  • Interfaces
  • Services

26
Layers
  • The idea of introducing layers of software
    reduces the design complexity. It divides the
    large problem into smaller ones.
  • The number, name, contents and function of each
    layer vary from network to network.
  • However for each network the idea is that one
    layer offers something to a second layer without
    the second layer knowing how the first layer is
    implemented.

27
Protocols
  • Provided two networks adhere to the same set of
    layers layer n on one machine can
    (virtually)communicate with layer n on another
    machine.
  • The rules and conventions used in this
    conversation are known as the layer n protocol.
  • A protocol is an agreement between the
    communicating parties as to how the communication
    proceeds.

28
Interfaces
  • Interfaces exist between adjacent layers.
  • The interface specifies what one layer is
    offering to the other layer.
  • Analogous to Object-Oriented concept of
    Encapsulation
  • One of the most important aspects of designing
    the network software is to provide clean, well
    understood interfaces. Minimise the amount of
    information that has to be passed from layer to
    layer.
  • Once a layers interface is defined many
    implementations of that layer can exist. The only
    stipulation is that the interface is adhered to.

29
Design Issues for the layers
  • Addressing identifying senders and receivers.
  • Data transfer rules- Simplex, half duplex, Full
    duplex.
  • Error control - Agree on a protocol.
    Implementation of the protocol.
  • Order of the messages
  • Fast sender swamping a slow receiver - feedback
    or an agreed size is required.
  • Length of messages - Too large/too small.
  • Multiplexing - use the channel for multiple
    unrelated conversations.
  • Multiple routes - How to choose the route.
    Physical and logical choices.

30
Reference Models
  • Two reference models are considered
  • The OSI (Open Systems Interconnection) Reference
    Model initiated in the 1970s matured in the late
    1980s and early 1990s
  • TCP/IP initiated through work carried out in the
    late 1960s, matured and adopted in early 1990s

31
Open Systems Interconnetion Model
  • Developed by the International Standards
    Organisation (ISO)
  • The model deals with connecting open systems i.e.
    systems that are open for communication with
    other systems.

32
Principles used to arrive at the Seven Layer
Architecture
  • A layer should be created where a different level
    of abstraction is needed.
  • Each layer should perform a well defined function
  • Standardisation issues.
  • Minimise data that has to travel between the
    layers
  • Large enough number of layers to support distinct
    functionality but not too large a number to
    create an unwieldy architecture

33
Network Protocols
  • Common language on the network
  • Define network components interactions
  • Actions/requests
  • Responses
  • Defined in standards
  • ISO Standards
  • IEEE Standards (mainly at physical and mac)
  • ITU Recommendations
  • IETF Request For Comments (RFC)

34
The TCP/IP Reference model
  • The grandparent of all computer networks the
    Arpanet research network sponsored by the
    Department of Defence (DoD) in America.
  • The network used leased lines to connect
    government offices and universities together.
    When satellite and radio networks appeared there
    were problems. The thinking for TCP/IP began.
    TCP/IP is named after its two primary protocols.
  • TCP- Transmission Control Protocol
  • IP- Internet Protocol
  • A layered architecture used to connect multiple
    networks together in a seamless way was one of
    the design goals from the very beginning
  • Connections should remain intact even if there
    was some subnet damage.

35
The Physical Layer
  • The Physical Layer is the lowest layer and is
    concerned with wiring and electrical standards.
    The design issues have to do with making sure
    that when a sender sends a 1 bit that the
    receiver receives a 1 bit and not a 0 bit.
  • Example issues to be agreed when building this
    layer
  • How many volts to represent a 1
  • How many volts to represent a 0
  • How many microseconds a bit lasts.
  • Does transmission proceed simultaneously in both
    directions
  • How are connections established and torn down
  • How many pins are on connectors and what each pin
    does.
  • What kind of transmission medium, wired, fiber
    optic

36
Communication between End-Systems
Figure is courtesy of B. Forouzan
37
Data Link Layer
Figure is courtesy of B. Forouzan
38
Duties of the Data Link Layer
The data link layer is responsible for
transmitting frames from one node to the next on
the same network.
Figure is courtesy of B. Forouzan
39
Packetizing Addressing
  • Packetizing Encapsulating data in frame or cell
    i.e. adding header and trailer
  • Addressing Determining the address of the next
    hop (LANs) or the virtual circuit address (WANs)

Figure is courtesy of B. Forouzan
40
Error Control Flow Control
  • Error Control Detect errors in received data
    and attempt to correct them
  • Error Detection
  • Error Correction
  • Flow Control Prevent the sender from
    overwhelming the receiver
  • Go-back-N
  • Sliding Window

41
Medium Access Control
  • Control the access to a shared medium to prevent
    conflicts and collisions
  • Aloha
  • CSMA/CD or CSMA/CA

Figure is courtesy of B. Forouzan
42
Analogy Point-to-Point Communication
  • Simple Synchronization

Phone conversation
43
Analogy Shared Medium
  • Synchronisation is more complex

44
Asynchronous Systems
  • Round robin
  • Good if many stations have data to transmit over
    extended period
  • Reservation
  • Good for stream traffic e.g audio, video
  • Contention
  • Good for bursty traffic
  • All stations contend for time
  • Distributed
  • Simple to implement
  • Efficient under moderate load
  • Tend to collapse under heavy load

45
Multiple-Access Protocols
Figure is courtesy of B. Forouzan
46
LAN Technologies - Ethernet
  • Developed by Metcalfe 1972/3 while at Xerox PARC
  • Standards in 1978, 1995, 1998
  • Types of Ethernet
  • Original Ethernet
  • Switched Ethernet
  • Fast Ethernet
  • Gigabit Ethernet
  • Medium Access Control
  • CSMA/CD
  • IEEE 802.2 Logical Link Control

Metcalfes Ethernet sketch
47
LAN Technologies - Evolution of Ethernet
  • 1972/73 defined for coaxial cable
  • Fast Ethernet used mainly unshielded twisted pair
    (UTP)
  • Gigabit Ethernet now common in desktops and
    laptops
  • 10GB Ethernet used mainly for backbone

48
802.3 MAC Frame
  • 64-bit frame preamble (10101010) used to
    synchronize reception
  • 7 bit preamble (10101010) 1 start flag
    (10101011)
  • Maximum frame length 1518 bytes
  • ? max 1500 bytes payload
  • Minimum frame length 64 bytes
  • ? min 46 bytes payload

Figure is courtesy of B. Forouzan
49
Ethernet Addresses The MAC Address
  • A unique 48 bit long number
  • Eg 00A04A211913
  • Types of Addresses
  • Unicast delivered to one station
  • Multicast delivered to a set of stations
  • 01-80-C2-00-00-00 Spanning tree (for bridges)
  • 03-00-00-00-00-01 NETBIOS
  • Broadcast delivered to all stations
  • FF-FF-FF-FF-FF-FF

vendor-specific
50
Non-bridged and Bridged Networks
  • Extension of Networks
  • Repeaters, Hubs - Physical Layer
  • Bridges, Switches - Data Link Layer
  • Routers - Network Layer
  • Collision domains
  • Collision affects all machines in one segment

Figure is courtesy of B. Forouzan
51
Switched Ethernet
  • Switch delivers packets to individual machines
  • Without affecting communication with other
    machines
  • Collisions only occur on individual links

Figure is courtesy of B. Forouzan
52
Full-duplex Switched Ethernet
  • No collisions
  • One line to send
  • One line to transmit

Figure is courtesy of B. Forouzan
53
Comms Rooms
54
Switches in Comms Rooms
55
Wireless (1/2)
  • IEEE 802.11 standard of 1997 started the
    revolution with 2Mbps top speed
  • Now on 802.11g with 54Mbps
  • 802.11n to promise 150Mbps
  • Referred by some as Wireless Ethernet
  • Shares significant similarities with original bus
    style Ethernet
  • Reliability and Performance much less than wired
    network
  • Current max speed 54Mbps shared by all on same
    base station
  • Prone to interference and poor reception
  • Speed drops under poor conditions to reduce
    errors
  • Range 100m in open much less in office situation

56
Wireless (2/2)
  • Star like network
  • Your laptop talks to a access point which
    connects to your wired network
  • Laptop which move been access points to keep the
    strongest signal
  • Uses the Industrial, Medical and Scientific Band
  • No licence needed
  • Healthcare staff should be aware this shared use
    and verify before installation that there wont
    be a conflict
  • Advantages
  • No need to install ethernet cabling everywhere
  • Network access everywhere in range

57
The Network Layer
  • The Network Layer is concerned with controlling
    the operation of the subnet. A key design issue
    is determining how packets are routed from source
    to destination. They can be static, dynamic.
  • Example issues to be agreed when building this
    layer
  • Routing mechanisms
  • How is subnet congestion to be dealt with
  • How are costings included- national boundaries
  • Addressing mechanisms.
  • In broadcast networks the network layer may be
    very thin or non-existent.

58
Position of the Network Layer
  • Sends frames through data link layer
  • Accepts data from transport layer

59
Duties of Network Layer
  • Problems the Network Layer needs to address
  • Transfer over networks of various architectures
  • Addressing on a global scale
  • Adjusting to maximum transmission units
  • Hop-to-hop delivery provided by data link layer
  • Transfer of packets between end systems provided
    by network layer

60
Switching in the Internet
  • Connection-oriented communication
  • Connection exists between sender and receiver for
    duration of communication
  • Connection-less communication
  • Data between sender and receiver

61
The Scenario
  • Computer A establishes IP address of Computer B
  • Computer A creates IP packet with address of
    Computer B as destination and its own IP address
    as source
  • Routers are responsible to direct packet towards
    destination

62
The Scenario
  • Best route Smallest number of hops?

63
The Scenario
  • Best route
  • Fastest round-trip time?
  • Highest Bandwidth?

64
Routing Basics
  • Routing Tables
  • Creating tables
  • Dynamic vs. Static
  • Maintaining tables
  • Periodic vs. Aperiodic

65
Structure of the Internet
  • Autonomous Systems
  • e.g. Companies, ISPs, 3rd-level Institutions

Autonomous Systems
66
Autonomous Systems
  • Stub network
  • Network that does not forward to other network
  • Transit network
  • Network that forwards traffic between other
    networks
  • Point-to-point link

Transit Network
Point-to-Point
Stub Network
67
Yet another Layer ?!?
  • Transport Layer TCP
  • Why should you care?
  • Applications use TCP as main communication
    mechanism
  • HTTP
  • Remote procedure calls (RPC)
  • File Transfer

68
Network Layer vs Transport Layer
Network Layer Transport Layer
Communication between two nodes Communication between processes
Best effort delivery Ordered, guaranteed delivery
Connection-less communication Connection-oriented communication
69
Transport Layer
  • Process-to-Process Delivery

70
IP Addresses Port Numbers
  • IP Addresses determine the host
  • Port Numbers determine the application

71
Communication at Transport Layer
  • Comms at Transport Layer from port to port
  • IP implementation multiplexes depending on
    protocol field in IP header

72
Client-Server Paradigm
73
Problems
  • Connection establishment
  • Connection termination
  • Ordered Delivery
  • Retransmission strategy
  • Duplication detection
  • Crash recovery
  • Flow control

74
Section 4 - Network Hardware
  • Connecting hosts and networks require hardware
    devices which include..
  • Networking and Internetworking Devices
  • Repeaters
  • Bridges
  • Hubs
  • Switches
  • Routers
  • Gateways
  • Brouters
  • Modems
  • Transmission Media

75
Networking and Internetworking Devices
  • These devices can be divided into 3 categories
  • Repeaters,
  • Bridges,
  • Routers and Gateways.
  • Repeaters and Bridges are used at the Networking
    of hosts
  • Routers and Gateways are used for Internetworking

76
Repeaters and Bridges
  • Repeaters
  • Operate at the physical layer. They regenerate
    signals.
  • Bridges
  • Operate at the physical and data link layers.
  • They are used to divide a network into segments
    and can control traffic flow and are useful for
    securing the network.
  • They can also regenerate signals.

77
What is a Switch
  • A layer 2 device Data Link Layer
  • Builds a table of the MAC addresses of devices
    attached on each port
  • Store and Forward
  • Switch receives a packet
  • Verifies it is error free
  • Looks at its destination MAC
  • Sends the packet on
  • Cut Through
  • Starts to forward packet once it reads the
    destination address
  • No error checking
  • Improved performance

Photo thanks to Cisco Systems
78
What is a Router
  • A layer 3 device
  • Works at physical, data link and network layers
    e.g. Internet Protocol (IP) level
  • Is a bridge between a number of distinct networks
  • Example your internal network and the internet
    beyond
  • Range from simple devices
  • ADSL router for home users
  • To
  • Extremely complex enterprise level
  • Looks at the destination of each IP packet and
    determines where it would be sent on for its next
    hop
  • Tries to select the best route

79
Other Devices
  • Hubs
  • A central device that acts like a multiport
    repeater
  • Date mainly from the time of non switched
    ethernet
  • Brouters
  • A single or multiprotocol router that sometimes
    acts as a bridge and sometimes as a router

80
Connecting Devices and the OSI Model
81
ADSL Modem for the 21st Century
  • Normal telephone lines support only a subset of
    the frequencies found in human speech
  • This limits the available bandwidth
  • ADSL uses part of this untapped bandwidth
  • Download bandwidth typically greater than upload,
    hence the A for Asynchronous
  • Suits the needs of the consumer market
  • Business users may wish to get equal
  • Quite vulnerable to noise
  • Limits on your distance from exchange
  • Further away the slower the available speed
  • Combined with VPN a true work from home solution

82
Transmission Media
  • Transmission Media Characteristics
  • Bandwidth
  • Response Time for a request
  • Transmission Media Types
  • Twisted Pair
  • Coaxial cable-
  • Fiber Optics
  • Wireless Media Radio, Microwaves, Infrared,
    Lightwave

83
Twisted Pair
  • The wire consists of two insulated copper wires
    about a mm thick, normally 24 gauge solid core
    copper.
  • The purpose of twisting the wires is to reduce
    electrical interference. (two parallel wires
    would act as an antenna). Various categories of
    cable
  • Many twisted pair cables can be bundled together,
    typically 4 pairs
  • They can be used for analog and digital
    transmission.
  • The bandwidth depends on the thickness of the
    wire and the distance travelled.
  • Shielded Twisted Pair (STP) and Unshielded
    Twisted Pair(UTP)

84
Twisted-Pair Cable
85
Effect of Noise on Parallel Lines
? The McGraw-Hill Companies, Inc., 1998
86
Noise on Twisted-Pair Lines
? The McGraw-Hill Companies, Inc., 1998
87
Unshielded Twisted-Pair Cable (UTP)
  • Most common type of cable used in computer
    networks
  • 8 wires forming 4 pairs
  • Different qualities
  • Cat 3 for 10Mbps
  • Cat 5 - for 100Mbps
  • Cat 5e for 1Gbps
  • Most common in current use
  • Cat 6 better for 1Gbps may allow 10Gbps
  • Best to future proof to avoid pain later
  • Cables of different types look identical
  • Cable type is printed on the side

88
Shielded Twisted-Pair Cable
? The McGraw-Hill Companies, Inc., 1998
89
Fiber Optics
  • An optical transmission system has three
    components
  • The light source
  • The transmission medium
  • The detector.
  • A pulse of light indicates a 1, lack of light
    indicates a 0.
  • The transmission medium is a unidirectional ultra
    thin fibre of glass or plastic
  • The aim is to get the angle of incidence of the
    light at such a point to make the light refract
    back into the medium. In the case of a fibre
    optic cable this means the light is trapped
    within the cable.
  • At the centre of the cable is the glass/plastic
    core which is surrounded by a glass cladding and
    then a plastic coating.

90
Transmission Media Performance
Medium Cost Speed Attenuation EMI Security
UTP Low 1-100Mbps High High Low
STP Moderate 1Mbps-1Gbps High Moderate Low
Coax Moderate 1Mbps-1Gbps Moderate Moderate Low
Optical Fibre High 10Mbps-10Gbps Low Low High
Radio Moderate 1-54Mbps Low-High High Low
Microwave High 1Mbps- 10Gbps Variable High Moderate
Satellite High 1Mbps- 10Gbps Variable High Moderate
Cellular High 9.6-19.2Kbps Low Moderate Low
91
Example Sizes of Medical Images
92
  • Network Users
  • Developers
  • Administration staff (software and hardware)
  • End users (specialised users, general public)
  • Uses of Networks
  • Resource Sharing- locally or over considerable
    distance.
  • High Reliability- multiple CPUs, replication of
    files.
  • Saving money- Price of PCs compared to
    mainframes.

93
  • Scalable solutions- The network can grow as the
    needs do
  • Communication medium- supporting team work
  • Accessing remote information- banking, health
    issues, hobbies, shopping
  • Person to person communication- e-mail, instant
    messaging, video conference
  • Interactive entertainment- films, games, live
    shows.

94
Uses of Networks in Healthcare?
  • Communicating into/out of and between hospitals
  • Paging Staff
  • Networking instrumentation
  • Maintenance of instrumentation
  • To aid communication
  • Professional to professional.
  • Professional to patient.
  • Patient to patient.
  • Sharing Information of all types

95
Network and Distributed Systems
  • There is some confusion over these two terms.
  • Hardware is required for both to operate
  • The distinction is in the software.
  • In a distributed system the existence of the
    autonomous computers is transparent.
  • The system is concerned with doing a job and not
    with how the connections are established and
    managed.
  • A distributed system refers to software built on
    top of a network.
  • With a network the user needs to explicitly deal
    with the network in terms of logging on, deciding
    which computer to use and managing the network.

96
Section 6 - Security
  • Security Issues
  • Virtual Private Networks
  • Issues with wireless networks
  • Methods of attack
  • Risks

97
Security Issues
  • Secrecy
  • Keeping information out of the hands of
    unauthorised users.
  • Authentication
  • Making sure you are talking to the right person.
  • Data Integrity control
  • Making sure the data is correct.
  • Security effects each layer in the network
    design.

98
No Network Is Secure
  • Original Ethernet
  • Every host on the bus could see and capture every
    transmission made
  • Trivial to recover passwords, web pages you
    viewed
  • The physical network itself cannot be considered
    to be secure
  • Wires can be tapped
  • Wireless communications available to all within
    range with a suitable receiver
  • Need to trade off the strength of security with
    the practicality of the measures
  • Users when faced with a complex process may
    attempt to undermine the system
  • Sharing of passwords or not logging out

99
Wireless Networks
  • Extremely vulnerable to attack
  • Anyone with a suitable radio can listen
  • IEEE 802.11 originally used a 40 bit WEP key
  • Shared encryption key by all users of the network
  • Later versions supported a 104 bit key
  • Proved to be very easy to crack in both versions
  •  WiFi Protected Access (WPA/WPA2)
  • Based on 802.11i standard
  • EAP extensible Authentication Protocol
  • Authentication framework not a protocol
  • Can integrate with existing authentication
    systems
  • 802.1x

100
  • Best practice in Network Management is to heavily
    restrict access to external users or to block it
    totally
  • Avoid potential security issues
  • Protect from hackers
  • What of legitimate users
  • People who work at other locations
  • Particularly relevant concerns in the Healthcare
    Domain

101
VPN Virtual Private Network
  • Not strictly a security solution
  • Two implementations
  • Connecting you to a remote network
  • A network within a network
  • Allows you to access resources on another network
    as if you where connected directly
  • A secure encrypted tunnel between your computer
    and others on the same network
  • Typically requires a dedicated VPN box on the
    office end network to provide the service

102
VPN - Connecting you to a remote network
  • Ideal for a single user
  • Work from home, on the road, other institution
  • User needs VPN client software
  • Setup can be complex for users
  • Need to implicitly log in to access the network
  • Not transparent
  • Potential security risk if users computer is
    breeched
  • Hacker may have access into network

103
Methods of Attack (1/3)
  • Impersonation
  • Using someone elses password or a terminal that
    is already logged on.
  • Active wire-tapping
  • Connecting a device(authorised/unauthorised) to a
    communication link to obtain access to data
    through the generation of false messages.
  • Passive wire-tapping
  • Monitoring data coming over a communication link.
  • Traffic flow analysis
  • Analysing the frequency of data traffic, seeing
    which data is encrypted and which is not.
  • Eavesdropping
  • interception of information

104
Methods of Attack (2/3)
  • Replay
  • Play back a recording of a communication
  • Routing Table modification
  • Sending messages to the wrong address or multiple
    addresses.
  • Audit Trail Information Modification
  • To cover up an attack.
  • Operational Staff Table Modification
  • To change access rights.
  • Bogus Frame insert
  • Inserting bogus information as a frame.
  • Data Portion Modification
  • Modify the data portion of a message.
  • Viruses

105
Methods of Attack (3/3)
  • Sequencing Information Modification
  • Change the order of the pieces of information.
  • Message Deletion
  • Removing the message completely
  • Protocol Control Information modification
  • To send data to a different location.
  • Misuse of resources
  • Swamping communication lines Denial of service
  • Interruption of power supply
  • Denial of service
  • Malicious physical damage
  • Denial of service
  • Theft
  • Parts of computers or entire computers could be
    stolen. Confidentiality issues arise.

106
Disposal of computer hardware
  • You typically contract a third party to securely
    shred paperwork, but you skip a used computer.
  • Computer can store a virtually unlimited amount
    of data in a easy to search format
  • Serious privacy issues concerning medical records
  • Computer may have no confidential information
    but!
  • Usernames, passwords, security certificates and
    so on for networked information may be stored on
    the computer, thus allowing access
  • Essential the contents of the hard disk be wiped
    not just deleted
  • Most operating systems have the ability to do
    this
  • Or remove hard drive and use a sledgehammer

107
Section 6 - The Internet and the World Wide Web
  • Addressing and Domain Names
  • Who is in charge
  • Relationship between IP address and hostnames
  • Arrangements for .ie domains

108
Internet Addressing and Domain Names
  • To be able to identify a host on the
    internetwork, each host is assigned an address
  • Internet Protocol address.
  • Addresses are assigned in a delegated manner.
  • The Internet Corporation for Assigned Names and
    Numbers (ICANN) has responsibility for Internet
    Protocol (IP) address space allocation
  • What is ICANN?
  • As a private-public partnership, ICANN is
    dedicated to
  • preserving the operational stability of the
    Internet
  • to promoting competition
  • to achieving broad representation of global
    Internet communities
  • to developing policy appropriate to its mission
    through bottom-up, consensus-based processes.

109
Internet Addressing and Domain Names
  • ICANN are the top body. They comprise IANA
    http//www.iana.org/
  • Users are assigned IP addresses by Internet
    service providers (ISPs). ISPs obtain allocations
    of IP addresses from a local Internet registry
    (LIR) or national Internet registry (NIR), or
    from their appropriate Regional Internet Registry
    (RIR)
  • APNIC (Asia Pacific Network Information Centre) -
    Asia/Pacific Region
  • ARIN (American Registry for Internet Numbers) -
    North America and Sub-Sahara Africa
  • LACNIC (Regional Latin-American and Caribbean IP
    Address Registry) Latin America and some
    Caribbean Islands
  • RIPE NCC (Réseaux IP Européens) - Europe, the
    Middle East, Central Asia, and African countries
    located north of the equator

110
Internet Addressing and Domain Names
  • The .org domain is operated by Public Interest
    Registry. It is intended to serve the
    noncommercial community, but all are eligible to
    register within .org.
  • The .com domain is intended to serve the
    commercial community.
  • The .gov domain is reserved exclusively for the
    United States Government. It is operated by the
    US General Services Administration.
  • The .edu domain is reserved for postsecondary
    institutions accredited by an agency on the U.S.
    Department of Education's list of Nationally
    Recognized Accrediting Agencies and is registered
    only through Educause.
  • The .net domain is reserved for networks usually
    reserved for organizations such as Internet
    service providers

111
IP and Internet Addressing
  • Currently there are two types of Internet
    Protocol (IP) addresses in active use
  • IP version 4 (IPv4) and IP version 6 (IPv6).
  • IPv4 was initially deployed on 1 January 1983 and
    is still the most commonly used version.
  • IPv4 addresses are 32-bit numbers often expressed
    as 4 octets in "dotted decimal" notation (for
    example, 192.0.32.67). Can cater for 4.4 billion
    addresses
  • Deployment of the IPv6 protocol began in 1999.
    IPv6 addresses are 128-bit numbers and are
    conventionally expressed using hexadecimal
    strings (for example, 10800008800200C417A).

112
IP Addresses
  • 32-bit number in IPv4
  • 4,294,967,296 addresses
  • IP addresses are unique and universal
  • with some exceptions
  • Dotted decimal notation
  • Bytes of binary notation represented as decimal
    separated by dot
  • Internet hosts have both IP addresses and
    hostnames
  • wilde.cs.tcd.ie 134.226.32.55

113
Sending IP datagrams over Ethernet
  • When the network layer wishes to send data across
    the data link layer
  • IP address needs to be mapped to an ethernet
    address

114
Mapping Domain Names
  • Hostname - wilde.cs.tcd.ie
  • Internet Address - 134.226.32.55
  • How does a machine translate a fully qualified
    hostname into an IP address?
  • It consults its nearest Domain Name Server (DNS)
  • The local Nameserver knows the mappings for local
    machines and
  • At least one root nameserver which knows all
    nameservers for the top level domains.

115
.ie domains
  • All registrations handled by the IE Domain
    Registry - www.iedr.ie
  • Was based in UCD until 2000, now a independent
    non profit making body
  • You are required to prove a connection to the
    domain name sought
  • 10th Feb 2008
  • Total number of domains 118,515
  • In Jan 1995
  • Total domains 347

116
Growth in .ie domains
117
Section 7 Telemedicine
  • What is it?

118
Definitions
  • Telemedicine is the rapid access to shared and
    remote medical expertise by means of
    telecommunications and information technologies,
    no matter where the patient or the relevant
    information is located. (CEC 1993)
  • Telemedicine has been defined in General Terms as
    Medicine practiced at a distance and as such,
    it encompasses both diagnosis and treatment, as
    well as medical education. (Journal of
    Telemedicine and Telecare, 1995)

119
Definitions
  • Telemedicine is the delivery of healthcare
    services, where distance is a critical factor, by
    all healthcare professionals using information
    and communications technologies for the exchange
    of valid information for diagnosis, treatment and
    prevention of disease and injuries, research and
    evaluation, and for the continuing education of
    healthcare providers, all in the interests of
    advancing the health of individuals and their
    communities. (World Health Organisation 1998)

120
Telemedicine
  • Many different definitions of Telemedicine. Be
    aware of this.
  • Telemedicine is a process not a technology. Can
    be applied to many different domains.
  • Can be used for patient/clinician,
    patient/patient, clinician/clinician
    communication.
  • Can be used to support training
  • As with all applications of technology,
    appropriateness is the key. The application
    should be clinically driven.

121
Definition
  • The WHO offers a holistic definition of
    telemedicine The delivery of healthcare
    services, where distance is a critical factor, by
    all healthcare professionals using information
    and communication technologies for the exchange
    of valid information for diagnosis, treatment and
    prevention of disease and injuries, research and
    evaluation, and for the continuing education of
    healthcare providers, all in the interests of
    advancing the health of individuals and their
    communities (WHO 2004)
  • Telecare, a term often associated with
    telemedicine, can be defined as "...the use of
    information and communication systems to give
    patients with or without their healthcare
    professional or informal carer access to
    information sources wherever they are located
    frequentlywithin patients' place of residence
    NHS (2004)

122
Characteristics of Telemedicine systems
  • Interaction style- Real Time, Store and Forward.
  • Data types- Text, Images, Sound, Video
  • Equipment
  • Action Direct Intervention, Advice
  • Patient numbers one patient, multiple patients
  • Duration

123
Some Advantages and Obstacles of Telemedicine
  • Advantages
  • Improved use of resources
  • Continuing professional development
  • Reduces unnecessary patient transfers
  • Facilitates homecare for the elderly and the
    chronically ill
  • Equitable access to care!
  • Links doctors with remote centres of excellence
  • Wireless links can be used in cases of lack of
    infrastructure
  • Obstacles
  • Patient and professional dissatisfaction in some
    specialities
  • Lack of standards
  • Security issues
  • Legal and ethical implications
  • Equipment failure
  • Lack of protocols of care for these new types of
    interactions.

124
History
  • Pre-electronic telemedicine
  • Accounts from the middle ages of a physician
    examining a patient for plague- the patient and
    the physician were on opposite sides of the
    river.
  • Prescribing by post was practised well before
    national postal systems were in place.
  • Electronic telemedicine
  • Telegraphy- equipment was developed to send an
    X-ray
  • Telephony- voice communication, computer networks
  • Radio- initially by morse code and later by
    voice.
  • Television- closed circuit television, video
    conferencing
  • Wireless communication- use of mobile phone
    technologies and satellites.

125
Research
  • Why is Telemedicine not in widespread use?
  • The technologies exist but the organisational and
    personal problems exist.
  • Lots of funding has been allocated and has been
    spent on projects analysing, testing and
    evaluating technical requirements.
  • More projects/research should be funded to show
    cost-effectiveness and evaluation of new
    Telemedicine applications.

126
Ethical and Legal Issues
  • Some projects in Europe have looked at certain
    aspects of this area (SEISMED, ISHTAR,
    TrustHealth and SIREN). They have mainly been
    concerned with the security and confidentiality.
  • More work needs to be done to research other
    aspects including accountability, responsibility,
    licensure, reimbursement, intellectual property
    rights, changes in consultation and referral
    patterns, defining the owner of patients,
    defining geographical catchment areas.

127
Economics/Evaluation
  • Need to compare the new technology with an
    alternative way of working. What is the system
    costing at the moment?
  • How to asses the cost of the new technology-
    equipment, software, installation, training,
    maintenance, legal, utilisation rates.
  • How do we asses the benefits- people getting
    well, shorter stays in hospital, less time spent
    with the expert, patient not having to travel,
    expertise experienced by the remote healthcare
    professional.
  • Methods are required if economic evaluation is to
    take place. Care should be taken when comparing
    costs across, domains, environments and time.

128
Practice
  • Teleradiology
  • Telepathology
  • Teledermatology
  • Telecardiology
  • Telepsychiatry
  • Teleorthopaedics
  • Surgical Consultations
  • TeleENT
  • Tele-EEG
  • Minor Injuries
  • Mobile Telemedicine
  • Maritime Telemedicine
  • Teleopthamology
  • Home Care
  • Telephone Services
  • Education
  • Telesurgery

129
Using Networks to Provide Equality of Care?
  • Network Infrastructures- Network hardware and
    network software
  • Network users
  • Software applications
  • Legislation
  • Standards
  • Delivering care (need experts on site)

130
Network Infrastructure
  • In order to avail of networked healthcare a
    network infrastructure must be in place.
  • This infrastructure requires an initial
    investment, maintenance investment and investment
    to keep it up to date
  • It is hard to see therefore even at the
    technology end how equality of care can be
    achieved.

131
Network Users
  • In various countries, regions and hospitals
    different levels of technical skill exist.
  • If we assume that all places have the same
    network infrastructure it still doesnt allow us
    achieve equality of care

132
Software applications
  • On top of the network infrastructure software
    applications.
  • Depending on economics, skill and awareness of
    users differences can exist.
  • Not everyone will be aware of the software
    applications that exist and the implications of
    choosing particular software e.g. from standards
    point of view

133
Legislation
  • Be aware that using networks allows the user to
    bypass physical boundaries thus enabling a
    specialist in Ireland to communicate with a
    patient in England. There are legal implications
    to this that havent been addressed.
  • Equality of care may not be possible due to these
    legalities. The closer you live to the specialist
    the better.

134
Standards
  • In order to have healthcare delivered to all
    areas standards are required.
  • Communication standards
  • Coding standards e.g. for diagnosing,
    prescribing.
  • Data set format standards
  • Semantic standards
  • If all areas do not agree to the standards then
    equality of care is not possible.

135
Experts on site
  • Even if all the infrastructure, software
    applications, standards, legislation and skills
    are equal is it possible to get equality of care?
  • Remember healthcare is ultimately delivered by
    human experts.
  • Technology can only be used to support the
    current processes of healthcare delivery or to
    make new processes possible.

136
TIE
  • Telemedicine Information Exchange (US)
  • http//tie.telemed.org/
  • Covers
  • Extensive bibliography (gt14,000 entries)
  • Projects
  • Events calendar
  • Funding sources
  • News
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