CH/S6CA/Nov. 2008
SOHO NETWORK DESIGN AND IMPLEMENTATION

The following phases are involved in the network development process:
i.
Need analysis
ii.
Design
iii.
Setup
iv.
Testing
v.
End-user support

Documentation is needed in different phases in the network development process.

One can go back to the previous phase(s) if necessary.
Need analysis


Need analysis begins with the acquisition of external information
i.
forecasts of how the new network/service will operate;
ii.
the economic information concerning costs; and
iii.
the technical details of the network’s capabilities
The role of forecasting.
i.
It is necessary to estimate the expected traffic intensity and thus the traffic load that the network must
support.
ii.
Traffic intensity
a.
It is a measure of the average occupancy of a server or resource during a specified period of time,
normally a busy hour.
b.
It is defined as the ratio of the time during which a facility is cumulatively occupied to the time this
facility is available for occupancy.
aL
R
where
a is the average arrival rate of packets (e.g. packets/sec)
L is the average packet length (e.g. in bits), and
R is the transmission rate (e.g. bits/sec).

c.
A traffic intensity greater than one means that the rate at which bits arrive exceeds the rate bits can
be transmitted and queuing delay will grow without bound (if the traffic intensity stays the same).
d.
If the traffic intensity is less than one, then the router can handle more average traffic.
The identified needs should be translated into user requirements and specifications.
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Design

The network should be designed in a way that it can meet every requirement generated in the need
analysis phase.

In the design phase, one should consider (with reference to Notes “SOHO Networking”)
i.
network layout
ii.
transmission media. (p. 14)
iii.
topology (p. 15-16)
iv.
protocol(s)
v.
network devices
vi.
server(s)
vii.
software
a.
b.
c.
viii.
cost
a.
b.

operating system (Windows server, Linux)
application software
utilities (network monitoring software)
setup cost (fixed cost)
on-going support cost (variable cost)
ix.
security measures
x.
scalability measures
xi.
internet access (broadband or leased line)
xii.
static IP addressing system or DHCP
Network Diagram
i.
The network will be built in the setup phase according to the network diagram.
ii.
In the above diagram, three personal computers and a server are connected to a switch; the server is
further connected to a printer and a gateway router, which is connected via a WAN link to the
Internet.
iii.
The network diagram will be kept updated during the end-user support phase to facilitate on-going
maintenance and support.
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iv.
A network diagram may include the following information::
a.
Network layout.
b.
Category / Model name of network devices / servers / user machines
c.
Location of devices / servers / user machines
d.
IP address of devices / servers (User IP addresses will not be recorded if DHCP is used)
e.
Machine names
f.
Transmission media used
g.
Other additional remarks are useful for further reference and support.
Cisco uses its own brand of networking symbols:
http://www.cisco.com/web/about/ac50/ac47/2.html

Here are some more sample network diagrams:
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Setup

In this phase, the actual network will be set up. Steps include:
i.
Wiring
ii.
Physical installation of machines
iii.
Installing additional components on machines (E.g. Extra hard disk for RAID, extra power supply_
iv.
Software Setup
a.
b.
c.
d.
e.

Installing OS
Other configurations (E.g. setting IP, joining domain)
Setting sharing resources like folders on harddisks.
Installing other software
To save time, we can install everything on a “template” machine, then clone the image of this
machine to other machines so that all machines will look similar in their settings.
Folder/file-sharing permissions:
Read, write, execute rights, etc.
Testing

Testing is the process used to justify whether the network installed in the setup phase fulfils the
requirements stated in the need analysis phase.

Test Plan:

i.
Written before conducting the test.
ii.
Used to specify what test cases should be conducted.
iii.
Should be drafted according to user’s requirement and the network design.
Test results should be recorded and stored in the Test Report.
End-user support

User training
i.
Teacher users how to use the system. E.g. login, print file, etc.
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
ii.
Tell the users the rules and best practice they should obey in using the system. E.g. password policy,
security policy, etc.
iii.
Documents involved: teaching materials, regulation documents.
Ad hoc support
i.
Solve uses’ problems upon requests
ii.
Supporting details should be recorded in a log for the following purposes:
a.
b.

Knowledge sharing between supporting team members
For further analysis (e.g. which printer brand goes wrong most frequently)
House-keeping Work. E.g.
i.
Regular backup
ii.
Server cleanup
iii.
Virus engine update
iv.
Installing software patches
v.
Update the network diagram if there is any change in the network (E.g. Changing router location)
Documentation

Document used in different phases:
Phase
Document(s)
Remarks
Need Analysis
User requirement,
specification
Capture requirements from users
Design
Network diagram
Record the layout of the network and the resources involved
Testing
Test plan
Include the test cases to be conducted (Done before
conducting the test)
Test report
Report the test results (Done after the test)
User manual / Training
materials
Teach users how to access the network
User regulations
State the rules users should obey in order to use the network
Maintenance log
Is used by supporting staff for recording for further reference
Network diagram
(updated)
When there is any change in the network layout, the network
diagram should be updated.
End-user
support

Documentation is an on-going process in network development process and should be involved in various
phases in network development.

User document (e.g. user manual and teaching materials) should be easy to read and avoid technical
jargons.

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
SOHO Network Management and Security
i.
Monitoring, fine-tuning and troubleshooting
ii.
Backup
iii.

a.
Importance
b.
Solution, e.g. RAID, UPS, network backup servers, etc.
Security threats and measures
a.
Threats: virus, worm, Trojan programs, spyware, unauthorized access, interception
b.
Measures: Anti-virus programs, authentication, access and user right control, packet filtering,
public and private key encryption, WEP, IPsec used in VPN, etc.
The major purpose of a database system is to provide users with an abstract view of the system. The
system hides certain details of how data is stored and created and maintained. Complexity should be
hidden from database users.
Data Abstraction

It refers to the suppression of details of data organization and storage and the highlighting of the essential
features for an improved understanding of data

There are several levels of abstraction:
i.
Physical Level:
a.
How the data are stored.
b.
E.g. index, B-tree, hashing.
c.
Lowest level of abstraction.
d.
Complex low-level structures described in detail.
Reference:
http://en.wikipedia.org/wiki/Entity-relationship_model
http://en.wikipedia.org/wiki/Er_diagram
http://www.edrawsoft.com
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