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									Unit 106:                   Principles of Computer Networks
NQF Level 3:                BTEC National
Guided learning hours: 60

Unit abstract
Learners thinking of careers within network technical support or network
management must have a good understanding of the underlying principles of
networking and how data travels around networks.
This unit starts by exploring the different types of networks and the standards
relating to network systems, including local and wide area networks. Networks can
be either wired or wireless systems and, although much of the underpinning content
is similar, this unit does make reference to both.
The hardware and software components used in networks and their operation are
explored and learners will build an understanding of their functions and services and
how they relate to each other. As users of networks, we work with them mostly
through the services that they provide, from simple services such as file sharing and
communications to more complex services involving security and account
For networks to be practical, they must be secure and the nature of them being
distributed across several physical locations, perhaps via a WAN, makes the ensuring
of security a complex business. Learners will understand key network security issues
as well as exploring the technologies used to create secure systems.

Learning outcomes
On   completion of this unit a learner should:
1     Know the types of network systems and related standards
2     Understand the hardware and software used in networking
3     Know the services provided by network systems
4     Understand how networked systems are made secure.

Unit content

1   Know the types of network systems and related standards
    Types of network: local area network (LAN); wide area network (WAN); WAN
    technologies eg frame relay, ISDN, ATM; value added network (VAN); logical and
    physical topologies eg star, bus, ring, mesh; network access methods eg CSMA,
    Token passing; OSI 7 layer model; choice of network to meet business need
    Network protocols and standards: eg TCP/IP, AppleTalk, UDP, 802.2, 802.3, FDDI,
    802.5; wireless technologies eg 802.11, infrared, Bluetooth; factors affecting
    range and speed of wireless technologies
    Application layer protocols: eg DNS, DHCP; HTTP; FTP; SMTP

2   Understand the hardware and software used in networking
    Network devices: workstations; servers eg print, mail, file, web, proxy; others eg
    network interface cards (NIC); features and functions
    Interconnection devices: eg modem, repeater, bridge, router, gateway, switch,
    hub; wireless access points; purposes, features and functions
    Connectors and cabling: leased line; dedicated line; media types eg STP,
    Category 5, coaxial, UTP, fibre optic; wireless; microwave and satellite links;
    cable standards eg 10Base-T
    Software: network operating system; virus checker; firewall; other eg email
    Commercial systems: eg Unix, Linux, Windows, Netware, Appleshare

3   Know the services provided by network systems
    Directory services: eg account management, authentication management
    Telecommunication services: communication eg email, internet relay chat (IRC),
    discussion boards; remote access eg via mobiles
    File services: file transfer; file sharing
    Application services: application software eg database, web, proxy; shared
    resources printing; storage space; Voice over IP (VoIP); mobile working;
    authentication eg users, hardware

4   Understand how networked systems are made secure
    Risk related business issues: risks to business; costs; responsibilities; systems and
    procedures eg password policies; disaster recovery; comparison with security
    issues for non-networked systems
    Securing data: authorisation permissions and access control lists; backing up and
    restoring; encrypting; others eg biometrics; physical security eg CCTV, locks
    Software: firewalls; malware (hostile, intrusive, or annoying software or program
    code) eg viruses, Trojans, worms, spyware, adware; levels of security risk for
    different malware; software protection eg antivirus, intrusion detection systems

Grading grid

In order to pass this unit, the evidence that the learner presents for assessment needs to demonstrate that they can meet all of the learning
outcomes for the unit. The criteria for a pass grade describe the level of achievement required to pass this unit.

Grading criteria

To achieve a pass grade the evidence must        To achieve a merit grade the evidence must       To achieve a distinction grade the evidence
show that the learner is able to:                show that, in addition to the pass criteria,     must show that, in addition to the pass and
                                                 the learner is able to:                          merit criteria, the learner is able to:
P1 describe the types of networks available      M1 compare the benefits and disadvantages of     D1 justify the design and choice of
   and how they relate to particular network        peer-to-peer network and client/server            components used in a particular
   standards and protocols                          networks                                          networked solution
P2 describe, using examples, why different       M2 design a networked solution to meet a         D2 evaluate the value of typical services
   network standards and protocols are              particular situation with specific               available from a network operating system
   necessary                                        requirements                                     directory service.
P3 describe the functions of a logical set of    M3 compare and explain the differences in
   interconnection devices                          data transfer rates between typical LANs,
                                                    WANs and mobile networks
P4 describe the key components required for      M4 explain the importance of the OSI seven
   client workstations to connect to a              layer model.
   network and access network resources
P5 give an outline description of the seven
   layer OSI model
P6 describe typical services provided by
P7 describe the business risks of insecure
   networks and how they can be minimised.

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Essential guidance for tutors

This unit is based on the principles of networking with a theoretical view to much
of the content. However, centres should try to ensure that as many varied learning
approaches are used as possible. Practical activities on real networks are
recommended, examples are offered in Assessment below.
Visits or talks given by outside professionals will be valuable — preparation may be
necessary to ensure that the guest speaker understands the level of programme
and is prepared to use appropriate language and respond to the learning outcomes
where possible.

As this unit has substantial theory it is important that centres make as much use of
varied assessment strategies as possible to maintain interest. This could include
the use of online or conventional testing, learner presentations, assignments or
question and answer sessions.
To achieve a pass grade, learners must achieve the seven pass criteria listed in the
grading grid. For P1, learners could produce a report using diagrams. Alternatively,
a small set of linked web pages could be appropriate.
For P2, technical detail can be limited but learners should be able to demonstrate
their awareness, perhaps via a written or verbal report or presentation that they
understand why different network standards and protocols are necessary. Examples
given should be realistic.
For P3, an observation sheet documenting and summarising a series of questions
and answers or discussion would be appropriate, alternatively a simple test. Most
of the related content is indicative, however it is important that the set represents
a logical set of components rather than a random list. The centre can provide
For P4, ideally learners should have the opportunity to set up a basic network and
the actual evidence of the network (photos, diagrams etc) could be supported by a
confirmation by observation record that this constructed network actually
functions. Learners would probably welcome the opportunity to talk through what
they did and this provides additional valuable evidence, alternatively log book
evidence can be used if needed.
For P5 and P6, a written report, presentation or set of web pages could be an
appropriate vehicle to provide the evidence.
For P7, learners could produce a report based on a centre-provided case study,
however the case study must be sufficiently rich to allow a wide range of issues to
be identified as relevant. Basing a report on a visit to a real company would be of
particular value and if this results in a restricted report then additional evidence
can be added via a documented post-visit discussion prompted by the tutor. For
example ‘I know that the company you visited did not have their network
connected to the internet but if they did what other security risks might that
bring?’. Or ‘I know that the company you visited does not have a disaster recovery
policy in place but what do you think that this should include?’.
To achieve a merit grade, learners must achieve all of the pass grade criteria and
the four merit grade criteria. For M1, learners should, ideally, have the chance to
see the operation of both types of networks and then the actual evidence
presented as verbal, written report etc would be based on real experience.
The evidence for M2 could evolve from that produced for P4 as long as a clear set
of specifications were available to be checked against. A scenario could be
provided by the centre
For M3, learners could use a simple table to summarise some key exemplar data
and then make references to this in an accompanying report. Ideally, learners
would be able to derive the performance data from actual experiments on real
For M4, a simple written report is the most obvious, however a short presentation
would also be appropriate.
To achieve a distinction grade, learners must achieve all of the pass and merit
grade criteria and the two distinction grade criteria. For D1 and D2, written reports
or presentations would both be appropriate.

Links to National Occupational Standards, other BTEC units, other BTEC
qualifications and other relevant units and qualifications
This unit can be linked with Unit 100: Computer Systems, Unit 102: Maintaining
Computer Systems, Unit 107: Network Management, Unit 108: Networked Systems
Security, Unit 109: Networking Basics (Cisco CCNA1) and Unit 110: Routers and
Routing Basics (Cisco CCNA2).
This unit has links to the Level 3 National Occupational Standards for CT

Essential resources
The tutor will need access to a LAN to demonstrate the configuration of protocols
and services. If a lab network is available, the tutor can demonstrate the
connectivity of hubs, routers, switches, etc. If it is not available, learners should at
least see the various interconnectivity devices. If a lab network is available,
learners can configure IP settings and create shared folders to access across the
The tutor should be able to demonstrate network security settings and should have
access to a range of security application software, including a firewall.

Indicative reading for learners
Burgess M — Principles of Network and System Administration, 2nd Edition (John
Wiley and Sons Ltd, 2003) ISBN 0470868074
Malik S — Network Security Principles and Practices (Cisco Press, 2002)
ISBN 1587050250
Olifer N and Olifer V — Computer Networks: Principles, Technologies and Protocols
for Network Design (John Wiley and Sons Ltd, 2005) ISBN 0470869828
Sybex — Networking Complete (John Wiley and Sons Ltd, 2001) ISBN 0782129145
Key skills

Achievement of key skills is not a requirement of this qualification but it is
encouraged. Suggestions of opportunities for the generation of level 3 key skill
evidence are given here. Tutors should check that learners have produced all the
evidence required by part B of the key skills specifications when assessing this
evidence. Learners may need to develop additional evidence elsewhere to fully
meet the requirements of the key skills specifications.

Application of number Level 3
When learners are:                   They should be able to develop the following
                                     key skills evidence:
•   designing a networked            N3.1    Plan an activity and get relevant
    solution to meet a particular            information from relevant sources.
    situation with specific
                                     N3.2    Use this information to carry out multi-
                                             stage calculations to do with:
                                             a amounts or sizes
                                             b scales or proportion
                                             c handling statistics
                                             d using formulae.
                                     N3.3    Interpret the results of your calculations,
                                             present your findings and justify your
Communication Level 3
When learners are:                   They should be able to develop the following
                                     key skills evidence:
•   describing the functions of a    C3.1a   Take part in a group discussion.
    logical set of interconnection
                                     C3.1b   Make a formal presentation of at least
                                             eight minutes using an image or other
                                             support material.
                                     C3.2    Read and synthesise information from at
                                             least two documents about the same
                                             Each document must be a minimum of
                                             1,000 words long.
                                     C3.3    Write two different types of documents
                                             each one giving different information
                                             about complex subjects. One document
                                             must be at least 1,000 words long.
Information and communication technology Level 3

When learners are:                  They should be able to develop the following
                                    key skills evidence:
•   describe the types of           ICT3.1 Search for information, using different
    networks available and how             sources, and multiple search criteria in at
    they relate to particular              least one case.
    network standards and
                                    ICT3.2 Enter and develop the information and
                                           derive new information.
                                    ICT3.3 Present combined information such as
                                           text with image, text with number,
                                           image with number.

Improving own learning and performance Level 3

When learners are:                  They should be able to develop the following
                                    key skills evidence:
•   designing a networked           LP3.1   Set targets using information from
    solution to meet a particular           appropriate people and plan how these
    situation with specific                 will be met.
                                    LP3.2   Take responsibility for your learning,
                                            using your plan to help meet targets and
                                            improve your performance.
                                    LP3.3   Review progress and establish evidence
                                            of your achievements.

Problem solving Level 3

When learners are:                  They should be able to develop the following
                                    key skills evidence:
•   designing a networked           PS3.1   Explore a problem and identify different
    solution to meet a particular           ways of tackling it.
    situation with specific
                                    PS3.2   Plan and implement at least one way of
                                            solving a problem.
                                    PS3.3   Check if the problem has been solved and
                                            review your approach to problem solving.
Working with others Level 3

When learners are:                  They should be able to develop the following
                                    key skills evidence:
•   designing a networked           WO3.1 Plan work with others.
    solution to meet a particular
    situation with specific
                                    WO3.2 Seek to develop co-operation and check
                                          progress towards your agreed objectives.
                                    WO3.3 Review work with others and agree ways
                                          of improving collaborative work in the

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