Download 1. Computer Networks - missions

Principles of
Networks
2010
Logistics Department
Action Againts Hunger
Document revision history:
Revision date
29/07/2009
21/05/2010
Author
Logistic Department
Logistic Department
Summary of changes
Initial release
KLV3 Format
Notes:
Table of contents:
1.
COMPUTER NETWORKS ....................................................................... 3
1.1.
What is a network? ............................................................................ 3
1.2.
When a network is needed? .............................................................. 3
1.3.
What makes up a network? ............................................................... 4
2.
COMPUTER NETWORKING ................................................................... 4
2.1.
Advantages of Installing a Network ................................................... 4
2.2.
Drawbacks of Installing a Network ..................................................... 5
3.
PROTOCOL: TCP/IP ................................................................................ 5
3.1.
What does it mean? ........................................................................... 5
3.2.
How to configure TCP/IP ................................................................... 5
3.2.1. Static ................................................................................................. 5
3.2.2. Dynamic (DHCP: Dynamic host configuration protocol) : .................. 6
4.
CABLE NETWORK .................................................................................. 7
4.1.
Installing Cable - Some Guidelines .................................................... 7
5.
WIRELESS NETWORK ........................................................................... 7
5.1.
Installing Wireless Network - Some Guidelines ................................. 7
6.
GLOSSARY.............................................................................................. 8
ACF - Kit Log V 3.6
4.4 ICT
Page 2 / 8
2010
1. Computer Networks
1.1.
What is a network?
A network is a collection of computers and devices connected to each other.
The network allows computers to communicate with each other and share resources and
informations.
1.2.
When a network is needed?
When you want to share resources or exchange data or mutualize an internet connection.
Example of resources:
- Printer
- Hard Disk (external or internal)
- Scanner
- Internet connection
- Kaspersky Update Centralization (see Kaspersky MP4 update procedure).
ACF - Kit Log V 3.6
4.4 ICT
Page 3 / 8
2010
1.3.
What makes up a network?
A network typically includes 4 things (besides the computers themselves).
Network interface cards (NICs):
- Cards that plug into the back (or side) of your computers and lets them send and
receive messages from other computers.
Cable/Electromagnetic wave:
- The medium/technology to connect all the computers together.
Hub/Switch/Router:
- Hardware to perform traffic control. Some are passive other are active elements.
Protocol:
- A set of communication rules to make sure that everyone speaks the same
language.
2. Computer Networking
2.1.
Advantages of Installing a Network
- Speed:
Networks provide a very rapid method for sharing and transferring files. Without a
network, files are shared by copying them to flash disks, then carrying or sending the disks from
one computer to another.
- Cost:
By sharing resources such as printer, scanner,..., you don't have to buy many items.
- Resource Sharing:
Sharing resources is another area in which a network exceeds stand-alone computers. Most
of missions cannot afford enough laser printers, modems, scanners, … for each computer.
However, if these or similar peripherals are added to a network, they can be shared by many
users.
- Flexible Access / Workgroup Computing:
Mission networks allow users to access their files from every computer. Users can also
work cooperatively through the network.
ACF - Kit Log V 3.6
4.4 ICT
Page 4 / 8
2010
2.2.
Drawbacks of Installing a Network
- Expensive to Install:
Although a network will generally save money over time, the initial costs of installation can
be prohibitive. Cables, network cards and the installation may require the services of a technician.
- Requires Administrative Time:
Proper maintenance of a network requires considerable time and expertise.
- File Server May Fail:
Although a file server is no more susceptible to failure than any other computer, when the
files server "goes down," the entire network may come to a halt.
- Security:
In case of "Workgroup" network, files are accessible to every body. User right access can
only be implemented on Domain Network. But it requires too much knowledge and means.
3. Protocol: TCP/IP
3.1.
What does it mean?
TCP Transmission Control Protocol et IP Internet Protocol
Computers are like humans beings in a sense that they need to speak the same language in
order to communicate.
IP address. Each computer needs to be identified (with a unique "address")
It can be compare to the Post Service. They need your name, your address; it must be an
unique information to work. IP address will be your unique id (name, first name…)
Subnet Mask will determine the number and the kind of IP address you will allow to your
group of computer to be connected to. Generally use 255.255.255.0
The gateway will be the equivalent of the nearest Post Office. It is where you will rout
your outside communications.
DNS server (Domain Name Server) will be able to translate the "Internet name" (ex.:
www.google.fr) into IP address (74.125.39.104)
3.2.
How to configure TCP/IP
There is 2 ways to configure TCP/IP on computers.
3.2.1. Static
You manage and enter manually the configuration.
This method is more secure because if a person wants to be connected to the network, she
will need to know the IP Addressing Plan.
ACF - Kit Log V 3.6
4.4 ICT
Page 5 / 8
2010
But it's time consuming because for every new person arriving on the base, you'll have to
configure the network settings. You'll also have to manage (keep up to date) the list of free IP
addresses.
Example of static TCP/IP configuration:
IP address: ex. : 192.168.1.114
Subnet Mask: 255.255.255.0
Default gateway: 192.168.1.205 (generally IP modem address)
DNS Server 1: 192.168.1.212
DNS Server 2: 192.168.1.208 (generally given by the provider)
Warning: Only items on same IP class address can communicate.
Ex.: 192.168.1.114 (subnet mask 255.255.255.0) will see 192.168.1.2
Ex.: 192.168.1.114 (subnet mask 255.255.255.0) won't see 192.168.44.2
3.2.2. Dynamic (DHCP: Dynamic host configuration protocol) :
An automatic IP address will be given to your computer. This can be done either by a
server or more frequently by a "router" (ex.: Wi-Fi router)
The DHCP is generally the TCP/IP configuration the most simple and efficient.
ACF - Kit Log V 3.6
4.4 ICT
Page 6 / 8
2010
4. Cable Network
4.1.
Installing Cable - Some Guidelines
When running cable, it is best to follow a few simple rules:
-
Always use more cable than you need. Leave plenty of slack.
Test every part of a network as you install it. Even if it is brand new, it may have
problems that will be difficult to isolate later.
Stay at least 1 meter away from fluorescent light boxes and other sources of
electrical interference.
If it is necessary to run cable across the floor, cover the cable with cable
protectors.
Label both ends of each cable.
5. Wireless Network
LAN
The term Wi-Fi is usually used by the public as a synonym for wireless Internet (WLAN)
A wireless access point (WAP) connects a group of wireless devices to an adjacent wired
Wireless adapters allow devices to connect to a wireless network
A wireless router allows wired and wireless Ethernet LAN devices to connect to a (usually)
single WAN device such as cable modem or DSL modem
Wired Equivalent Privacy (WEP) encryption was designed to protect against casual
snooping, but is now considered completely broken.
Wired Protected Access (WPA) which uses TKIP as a stopgap solution for legacy
equipment. Though more secure than WEP, it has outlived its designed lifetime.
WPA2 encryption standards were released. WPA2 is still considered secure, as of 2010.
5.1.
Installing Wireless Network - Some Guidelines
Follow a few simple rules:
-
Always buy a Wi-Fi router and not only Access Point.
If the office is very large (many floors), try with one Wi-Fi router to see if it
covers all the area.
Always protect your Wi-Fi access by a WPA encryption at least. Don't forget to
protect the admin access.
Renew frequently the password.
Be aware that the internet flow will be the same. It will be divided by the number
of users.
Implement some wired connection in case of problem with the Wi-Fi
ACF - Kit Log V 3.6
4.4 ICT
Page 7 / 8
2010
6. Glossary
 Local Area Network
A Local Area Network (LAN) is a network that is confined to a relatively small area
(capital, base, Paris HQ…)
 Wide Area Network
Wide Area Networks (WANs) connect larger geographic areas, such as Liberia, the
Africa, or the world
 Switch
A switch is a device that provides a central connection point for cables from
workstations, servers, and peripherals
 Router
A router translates information from one network to another
 Wireless LANs
Some networks are wireless. Wireless LANs use high frequency radio signals,
infrared light beams, or lasers to communicate between the workstations and the file
server or hubs.
 Wi-Fi
Wireless Fidelity synonym for wireless Internet (WLAN)
 Ethernet
Ethernet could be labeled as the great grand-father of all the other network types
 Internet
The collection of computers, networks and their interconnections which are more or
less publically accessible.
 Intranet
An intranet is a private computer network that uses Internet technologies to securely
share any part of an organization's information or operational systems with its
employees
 Extranet
An extranet can be viewed as part of a company's intranet that is extended to users
outside the company (e.g.: normally over the Internet).
 Fast Ethernet
It's a collective term for a number of Ethernet standards that carry traffic at the
nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s.
 Gigabit Ethernet
It's the next iteration, increasing the speed to 1000 Mbit/s
ACF - Kit Log V 3.6
4.4 ICT
Page 8 / 8
2010