SOHO Networking and Internet Activites
AS LEVEL
Computer Application
SOHO Networking and Internet Activities
YLLSS
In the syllabus, we have ...
Students should know how data is transmitted over the Internet and understand concepts of Internet Protocol (IP), Uniform Resource Locator (URL), Domain Name System (DNS) and Hypertext Transfer Protocol (HTTP).
Internet services and resources / · Students should be able to formulate an effective strategy for searching specific information on the World Wide Web by using search-engines, and be able to critically analyse the sources of information.
· Students should have experience of the use of the Internet for file transfer by using ftp, remote logon, locating and using an online chat, joining discussion forums and newsgroups.
· Students should be able to use plug-ins or players for multimedia elements found on the Internet.
· Students should understand the differences between a mail client and web mail, and the protocols (POP, IMAP, SMTP, etc.) used in sending and retrieving emails.
Ethical and social issues on the use of the Internet / · Students should be able to discuss critically issues arising from the digital divide, the emergence of a knowledge-based society and globalization.
· Students should be keenly aware of the issues of intellectual property, and be familiar with measures to safeguard themselves and their information on computers, by various means such as the installation of a firewall, filtering software, anti-spyware and anti-virus software. They should understand the use of cookies and the impact on user tracking.
· Students should understand the measures which ensure Internet security in data transmission, such as the use of a digital certificate and data encryption.
This module focuses on knowledge and skills essential in constructing SOHO networks. SOHO networks are small scaled networks suitable for small-and-medium enterprises (SMEs) which make up more than 90% of businesses in Hong Kong. Building up networking capabilities and infrastructure within SMEs will increase the productivity and enhance communication internally among staff and externally to customers or clients throughout the world.
Through the study of this module, students will gain an understanding of the basic principles of networking, and the knowledge and skills associated with the design, implementation and maintenance of a SOHO network. Students will also be aware of the common security threats to SOHO networks and the measures to improve network security. This module will give students a solid foundation on networking in general, and SOHO networking, in particular. Students will appreciate the practical nature of the module, regardless of whether they continue to pursue knowledge in this area in tertiary education or migrate to the workforce.
The time allocation for the module is about 32 hours (48 lessons).
Topics / RemarksA. SOHO Networking Basics / (8 hours)
Basic concepts of data communication and networking / · Students should be able to identify and describe the basic function of each component of a packet: header, data and trailer. They should also be able to explain briefly the use of packets in data transfer in a packet switching network.
· Students should understand the basic concepts of Internet Protocol (IP) addressing including the scheme and classes of IP addresses. They should understand the use of a subnet and know what a subnet an IP address belongs to from a simple subnet mask.
· Students should know the use of some common protocols including TCP/IP and DHCP, etc.
· Students should be able to explain the factors that need to be considered in choosing between a client-server network and a peer-to-peer network.
· Students should be able to compare and contrast the common types of communication links (e.g. modem dialup or cable modem, leased line, broadband and wireless, etc.) for Internet access in terms of data transfer rate, cost, and reliability.
Basic network components / · Students should be able to identify and describe the functions of the various components which make up the wired and wireless networks. These include the network interface cards (NICs), cables, hubs, switches, routers, broadband routers, gateways, wireless adapters, wireless access points, wireless routers, etc. They should also be able to describe and explain briefly the services provided by a network operating system.
SOHO network applications / · Students should be able to describe and appreciate the common applications of SOHO networking including resources sharing, Internet access, web serving, telecommunicating, etc.
B. SOHO Network Design and Implementation / (16 hours)
Need analysis / · Students should be able to conduct a simple need analysis on a proposed SOHO network and translate the needs identified into requirements and specifications.
Design / · Students should be able to design a network to meet the requirements generated in the need analysis and represent it in a diagram.
· Students should be able to justify their design based on technical, cost-effectiveness and other considerations.
Setup / · Students should have the experience of setting up simple Ethernet and wireless networks.
· Students should have the experience of sharing various resources (e.g. files, printers and Internet connection, etc.) among the networked computers / stations.
· Students should have the experience of setting folder/file-sharing permissions including read, write and execute rights, etc.
Testing / · Students should have the experience of validating a network system by testing it according to a simple test plan based on the requirements and specifications.
Documentation / · Students should be able to document the user requirements, a schematic diagram for the network and specifications of the network.
End-user support / · Students should be aware of the importance of adequate end-user support and training on the attainment of the benefits sought.
C. SOHO Network Management and Security / (8 hours)
Monitoring, fine-tuning and troubleshooting / · Students should develop the basic skills of monitoring and fine-tuning the performance of a simple network.
· Students should develop the basic skills of analysing problems associated with the use of a networked environment and performing troubleshooting for it.
Backup / · Students should be aware of the importance of backup in disaster planning and recovery measures.
· Student should know the common hardware and software components of a network backup solution, such as Redundant Array of Independent Disks (RAID), Uninterruptible Power Supply (UPS), network backup servers, network backup and recovery software, etc.
Security threats and measures / · Students should be able to describe the potential risks caused by the common network security threats including virus, worm and Trojan programs, spyware, unauthorised access, interception, etc.
· Students should be able to propose effective measures to improve network security for both wired and wireless networks. These include anti-virus programs, authentication, access and user right control, packet filtering, public and private key encryption, Wired Equivalent Privacy ( WEP), and IPsec used in Virtual Private Network (VPN), etc.
Networking
Practical implementation of network
Different Roles:
1. A device is needed to exchange the data between computers. (e.g. hubs, switches or routers)
2. Media of communication. (e.g. UTP cable, optical fiber, etc)
3. Hosts (e.g. a number of PCs with network interface cards installed)
There are a number of network card, below shows some of them:
A NIC card for desktop computer. Usually, NIC is built-in in a motherboard. This one is a PCI NIC card.A wireless NIC card, for desktop computer.
A NIC installed in a motherboard. Usually, it is inserted in a PCI slot.
A NIC installed in a PC which will be connected by a UTP cable.
A wireless PCMCIA NIC card,
It is usually in notebook computer.
Digital signals are sent forth and back between the computer and the NIC card, inside a computer, digital signals are sent in groups (parallel), however, when sending out of the computer, the data is sent serially, i.e. if “01011100”, inside a computer, it is sent in group, however, when, it is passing through the NIC, it first send “0”, then, “1” and so on.
Apart from network card, other connecting devices are required, for example:
RouterStackable switch
Here shows some common connecting media:
UTPOptical fibre
Difference between straight-thru wire and crossover wire (UTP)
Reason:
PC / Hub / Switch / ModemPC / crossover / straight / straight / straight
Hub / straight / crossover / crossover / crossover
Switch / straight / crossover / crossover / crossover
Modem / straight / crossover / crossover / phone cable
Reference: http://www.homenethelp.com/web/explain/about-ethernet-crossover.asp
Illustration of a network
A network is illustrated as below:
Practical Situation / Schematic representationType of computer network
LAN (Local Area Network) is a computer network which connects a number of computers and other devices within a limited geographical space such as a room or a office.
WAN (Wide Area Network) is usually formed by connecting various LANs spreading over a wide geographical area into a large network.
LAN
Two popular types of LANs are peer-to-peer and client/server.
Type / CharacteristicsPeer-to-Peer network / Every computer is connected directly to every other computer. Each computer can use information from, and provide information, to every other.
Client / Server network / Individual computers, called clients or workstations, are connected to central computer, called a server. The clients can access programs or files stored on the server.
There are two types of LAN, they are: peer-to-peer and client/server.
Peer-to-Peer / Client/ServerThe characteristics of Peer-to-Peer and Client/Server structure are:
Peer-to-Peer / l All computers are workstations (no server is assigned to maintain the network users)l Security is week.
Client/Server / l A server is assigned to maintain the network user accounts.
l File server is one of the applications in client/server structure. It can provide spaces for the user to store files in the server. And users are authenticated by username and password.
l Since the server can give different levels of rights(權力) to different users, so securities is high.
The way the network components incorporate to form a network
These components include
Connecting devices: Router, Switch, Hub (Their appearances are very similar)
Hub / Hub is some old-fashion connecting device, it broadcast all the message to all the ports it connected, so, it will easily slow down the transmission.Switch / Switch is used to connect several similar networks together, it acts as a bridge. Switch will not be able to distinguish different network, it will only recognize the IP address and then forward the message to the PC according to the MAC address.
Router / Router is used to connect two or more networks together. Router will be able to make use of subnet mask to distinguish different networks.
Connecting media: UTP, Optical Fiber
UTP / It is used to connect PC to some connecting devicesOptical Fiber / It is used to make connection between switches and routers.
Network Server Software vs Network Client Software:
NOS (Network Operating System) is used to manage network resources, control the flow of data, maintain security and track user accounts. It has two parts: Network Server Software and Network Client Software.
Network Server Software: installed in the server. It controls file access from the server’s hard disk, manages the print queue, and tracks user data such as user IDs and passwords.
Network Client Software: installed in the local hard disk. It gathers login information, handles drive mapping, etc.
Wireless LANs (WLAN):
The access point and the wireless NICs communicate by emitting and receiving radio waves. We called it RF (Radio Frequency).
a) Access Point / b) Wireless NIC / c) Wireless network PC card(mostly found in laptop) / d) Wireless USB adapter
Ethernet Networks(乙太網):
Ethernet is the most widely-installed local area network (LAN) technology. Specified in a standard, IEEE 802.3. An Ethernet LAN typically uses coaxial cable or special grades of twisted pair wires. Ethernet is also used in wireless LANs.
Connection between LANs:
Different LANs will utilize different network technologies. E.g. Ethernet, Token Ring, FDDI, ATM, Frame Relay, SMDS, and other networking technologies.
To connect different type of networks, a gateway is needed. Quite often it is the router. A gateway is responsible to connect two different networks.
Comparison of Speed in different network:
The speed of a network is measured in the unit bps (bit per second).
Type of network / Bandwidth(頻寬)LAN /
Ethernet (乙太網)
Fast EthernetGigabit Ethernet / 10M bps
100M bps
1G bps (~1000M bps)
Wireless LAN / Bluetooth
802.11b
802.11g / 1M bps
11M bps
54M bps
WAN / T1
T2
ISDN / 1.5M bps
44.7M bps
1.5 Mbps
Modem / Remote access through telephone line / 56K bps
Some important servers
Server Name /Description
File server (DC, domain controller) / A high speed computer that stores the programs and data files shared by users. Most file servers also store important information, like user accounts and the network information. Data in a file server are important and must be back up regularly.Mail server / A mail server provides e-mail services to users. Each user has a mailbox which stores the incoming mails and copies of sent mails.
Print server / A print server manages one or more printers. It allows a shared printer to be accessed by authorized users
Web server / A web server stores the contents of web pages created by users of a LAN. It entertains requests from other users on the Internet by delivering web pages.
Proxy server
/ A proxy server improves the efficiency of Internet access by temporarily storing copies of web pages visited by previous users of the same LAN. It also filters web pages to prevent users from accessing certain sites.Question: What are the advantages of networking of computers?
Share a folder for other network users:
Step 1Select the property of this folder
Step 2
Share this folder
Assign firewall setting
Step 3
Set user right
Step 4
Class work 1: