Transcript 2512 - Networking

G063 - Networking Computers
G063 + synoptic G061
Learning Objectives:
Synoptically (from G061) you should already be able to:
a. describe the advantages & disadvantages of networking
computers
Learning Objectives:
By the end of this topic you should be able to:
a. describe the advantages & disadvantages of networking
computers
b. compare the characteristics of a local area network (LAN), a
wide area network (WAN) and a virtual network;
c. describe client-server and peer-to-peer networks giving
advantages and disadvantages of each;
d. explain the importance of standards for communicating
between devices
e. explain how protocols are used to enable communication
f. discuss the use of networks of computers at work and at home
g. discuss the role of network hardware devices
What is a network?
• a group of computers connected together
– in order to share resources
• a computer not connected to any other is a
stand-alone computer
Advantages of Networking?
• share data
– sharing files
– collaborative working
– setting up an intranet
• share hardware
– peripherals such as scanners and printers
– often higher quality peripherals
• e.g. only have to buy one printer
Advantages of Networking:
• access own files from any machine
• share programs
– central rollout of software
– virus checking from a central location
• internal electronic communication
– e-mail, video conferencing, instant messaging (IM)
• centralised backup
Advantages of Networking:
• monitoring of system
– what are staff working on?
• central administration
– accounting and monitoring of resources
– access rights
Disadvantages of Networking?
• cost of network hardware
– hubs, switches, cables, server
• reliance on central equipment
– if server crashes, nothing works
• requires technical staff
– cost of employment (hiring network manager, technicians)
• viruses can spread more easily
• increased risk of hacking
– loss of data
• increase in office “chatter”
– less work done due to messaging, email not work related
• more users = more data traffic = ‘slower’ computers
Synoptic question:
A company owns several standalone computers, each with a
printer and connection to the Internet.
Describe two reasons why the company’s computers should
be networked.
[4]
G061 January 2010 Q3
Synoptic question:
Describe two reasons why the company’s computers should be
networked.
[4]
Sharing of files (1) more than one person can use the same file at the
same time (1)
Monitoring (1) use of the network can be monitored to make sure users
are not doing anything illegal (1)
Backup (1) can be centralised and scheduled to ensure nothing is lost (1)
Communication (1) sending emails/files to other users (1)
Centralised updates of virus/application (1) run on a single machine to
affect all connected machines (1)
Sharing peripherals (1) allows higher quality printers to be purchased and
all machines to use them (1)
G061 January 2010 Q3
Synoptic question:
A boat hire company has a head office in Cornwall and offers day
trips to go whale watching. The company has a website where
customers can look at the different types of trips offered and email
for further information.
The company is opening a booking office on the wharf next to the
boats. They need a computer in the booking office.
Describe three advantages to the company of networking the
booking office to their head office. [6]
G061 January 2009 Q6
Synoptic question:
Describe three advantages to the company of networking the booking office to
their head office.
[6]
Data can be backed up (1) without physically transporting it (1)
Monitoring of bookings (1) so the office know what to advertise (1)
Anti virus updates (1) can be done centrally (1)
Shared documents such as policies (1) immediate updates to both sites (1)
Access to files (1) to monitor employees (1)
Communication (1) to solve problems/update on bookings (1)
G061 January 2009 Q6
Learning Objectives:
By the end of this section you should be able to:
•
describe the characteristics of a local area network
(LAN),
•
describe the characteristics of a wide area network
(WAN);
Example questions:
Local Area Network (LAN)
• computers within a locally defined area
– computers are geographically close together
• room, building, site, campus
• connected via dedicated cables (or wireless devices)
owned by the company
• able to share local peripherals
• software and data can be shared
Wide Area Network (WAN)
• computers are geographically remote
• linked using telecommunications technology
– connected by third party cables (or mobile data link)
• telephone line, mobile ‘phone or leased line
– a modem, router or other device is needed to connect
Virtual Network
• computers physically connected on a single LAN
– or connected to LAN via Internet/WAN
• computers ‘grouped’ together virtually
– e.g. sub-LAN for each department
• network switching device ‘hides’ other computers on
the physical LAN
• VLAN users have access to same services as on LAN
– printers, files, software
• separates the traffic of different user groups
– only access certain network drives/files, printers ….
• VLAN offer secure remote access to existing resources
– as if working locally (useful for teleworkers)
Learning Objectives:
By the end of this section you should be able to:
•
describe client-server networks
•
describe peer-to-peer networks
•
give advantages and disadvantages of each;
Client-Server Network
Client-Server Network
Features:
• usually has powerful controlling computer(s)
–
•
the server
computers are connected to the server via a switch
–
•
or other communications hardware
server controls the access rights to resources
–
•
security, storage, printers, …
users have to log on at client computers
–
–
•
in order to gain access to resources
using username & password
users can log on at any computer
–
access own files & work from anywhere
Client-Server
Advantages:
• centralised backups
– users not involved!
• anti-virus managed centrally
– no user input required
• data available from any client
– users can work anywhere
• network security managed centrally
– access rights handled in a structured manner
• software deployed quickly to client machines
– user does not have to install software/updates
Client-Server
Disadvantages:
• expensive server(s) required
– high processing power, large hard disks, large memory
• network manager required to maintain network
– salary cost
• many clients = slower network
– since more data traffic
Peer-to-Peer Networking (P2P)
•
•
Peer-to-Peer Networking (P2P)
no central server
each computer performs its own functions
–
•
all computers have equal status
computers can share resources with others on the network
–
•
files or a printer
P2P networks are simple to install & set up
–
•
often found in homes & small businesses
installation of hardware/software has to happen on each machine
–
•
time consuming in terms of human resources
each machine has to be maintained individually
–
•
could lead to unreliability
back up is not centralised
–
•
greater responsibility on the individual user
data can be stored on any computer
–
could make data difficult to find
Peer-to-Peer Networking (P2P)
Advantages:
• no server required
– lower hardware costs
• no reliance on server
– if computer breaks down then only 1 user affected
• simple to install
– no need for extra staff = less cost
• network traffic minimal
– most resources provided by individual computers
Peer-to-Peer Networking (P2P)
Disadvantages:
• all processing done by each individual computer
– printing by one user may slow down work of another
• ‘ad-hoc’ security
– files may be available to an unwanted user
– printer might not be available to certain user
• anti-virus software installed/updated individually
– potential virus infections
• software has to be installed on each computer
– time consuming
• individual back up by users
– potential loss of data
Describe the purposes of each of the
following network components:
a.
b.
c.
d.
e.
f.
g.
h.
switch
hub
wireless access point
network interface
card
wireless network
interface card
router
Repeater
bridge
i.
j.
k.
l.
m.
n.
file server
applications server,
mail server,
proxy server,
print server,
backup server
Learning Objectives:
By the end of this section you should be able to:
•
discuss the use of networks of computers at
work and at home
–
uses, merits, drawbacks
Use of Networks:
Use of Networks:
Use of Networks: