Title: NT1210 Introduction to Networking
1NT1210 Introduction to Networking
- Unit 2
- Chapter 2, Introduction to Computer Networking
1
2Objectives
- Identify the major needs and stakeholders for
computer networks and network applications. - Identify the classifications of networks and how
they are applied to various types of enterprises. - Explain the functionality and use of typical
network protocols. - Use preferred techniques and necessary tools to
troubleshoot common network problems.
2
3Objectives
- Define a computer network.
- Identify the primary needs for computer networks
and network applications. - Draw the four major physical network topologies
bus, star, ring, and mesh.
3
4Computer Networking
- Use large variety of components that must work
together. - Move bits from one device to another.
- Bit Smallest unit of data, binary 1 or 0.
- Focuses on copying bits on one device to another.
- Computing devices include computers, gaming
systems, televisions, phones, tablets, GPS
navigation systems, watches, etc.
4
5An Informal General Definition of a Computer
Network
- Telecom Short for telephone communications
- Primarily focuses on role of traditional
telephone companies. - Datacom Short for data communications
- Older synonym for computer networking.
5
6Data Communication System
7Network Definition
- A network is a set of devices connected by
communication link to share resources - The devices are often referred as node.
- Node can be a computer, printer or any other
devices capable of sending and receiving data. - A link can be a cable, air, optical fiber, or any
medium which can transport a signal carrying
information
8Overview of Network Components
Figure 1-1 Sample Computer Network
9Defining a Network with User Applications
Computer Networks Cloud Representing Hidden
Parts of the Network
9
10 Purpose of a Network
- It can serve a variety of purposes including
- File sharing between two computers
- Video chatting across different parts of the
world - Surfing the Web
- Instant messaging (IM) between computer with IM
software installed. - E-mail
- Voice over IP (VoIP)
- A converged network is one that transports
multiple forms of traffic (video, voice, and data)
11Network Defined by Geography
- Local-area network (LAN)
- Wide-area network (WAN)
- Metropolitan-area network (MAN)
- Personal-area network (PAN)
12Network Defined by Resource Location
- Yet another way to categorize networks is based
on where network resources reside. - Network that have all the resources residing in a
server are called client server networks. - Network that have their resources on several
clients and no server is called a peer-to-peer
network
13Client-Server Network
Figure 1-13 Client-Server Network Example
14Peer-to-Peer Network
Figure 1-14 Peer-to-Peer Network Example
15Network Defined by Topology
16A bus topology connecting three stations
17A ring topology connecting six stations
18A star topology connecting four stations
19A fully connected mesh topology (five devices)
20 A hybrid topology a star backbone with three
bus networks
21Network Criteria
- Performance
- Depends on Network Elements
- Measured in terms of Delay and Throughput
- Reliability
- Failure rate of network components
- Measured in terms of availability/robustness
- Security
- Data protection against corruption/loss of data
due to 1.Errors 2. Malicious users
22Email
- Electronic Mail One of oldest networking
applications. - Sends mail electronically with bits.
- Write (type) email.
- Identify (type) senders and receivers email
addresses. - Give messages to email service.
- Email service delivers email to destination email
address.
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23Sending Email Networks Perspective
- Email servers (software running on computer in
network) must be ready to receive, process, and
hold emails for clients using SMTP (Simple Mail
Transfer Protocol). - To send email Email application sends mail to
outgoing mail server using POP3 (Post Office
Protocol, ver. 3). - Client must know location of outgoing mail
server. - To receive mail Email client must get mail from
its incoming mail server also using POP3. - Email application must know location of incoming
mail server.
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24Sending Email Networks Perspective
- Step 1 Barney sends an email to his outgoing
email server. - Step 2 Barneys outgoing email server must know
how to find the incoming email server used by
Fred more specifically, the incoming email
server used by email address fred_at_example.com. - Step 3 Freds incoming email server holds the
email for Fred, waiting until he next checks his
email.
Figure 2-5
Using Outgoing and Incoming Email Services
24
25Early Analog Voice Calls
- Majority of telephone services in USA for first
100 years grew from Bells original work and
business ventures. - Local telephone company (Telco) ran cable to each
home. - Inside Telco network, lots of other equipment
connect to create telephone network.
Figure 2-6
Big Picture View, Two Home Phones and the Telco
26Early Analog Voice Calls
- To create the call, the Telco creates an
electrical circuit all the way from one phone to
the other. Once the Telco creates the call by
creating an electrical circuit, the two people
can talk.
Figure 2-7
Electrical Circuit Between Two Phones to Carry
the Voice Call
26
27Digital Voice Calls
- The two home phones create an electrical circuit
into the Telco, but the analog circuit does not
extend from phone-to-phone.
Figure 2-8
Analog to the Phones, Digital in the Telco
27
28Break
Take 10
28
29A Deeper Look at One Application World Wide Web
- World Wide Web (the Web) Web browser software
which allows users access to Web may be single
most commonly used application in world. - Web works well for learning networking because
uses basic client-server model. - User sits at computer and uses web browser (Web
client). - Client indicates this software receives some
type of service from another device (information
from web server).
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30World Wide Web
- The web browser (client) and web server cooperate
so that the web browser can get a copy of the
information from a web server. The server
organizes information into pages called web
pages. The web browser asks the web server for a
web page, and the server sends the web page back
to the web browser.
Figure 2-12
Web Browser Requesting and Receiving a Web Page
from a Web Server
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31Web Servers (Hardware and Software)
Figure 2-18
Three Steps Web Server Sends Web Page into
Network
31
32Uncovering the Network Between the Application
Endpoints
- Small Lab Networks Devices typically all sit in
the same room. The network does not need to be
sophisticated at all. In fact, with just two
computers, just connect the two computers by
connecting a cable to the NIC in each computer.
Figure 2-28
A Simple Lab Network One Cable
32
33Local Area Network (LAN)
- A more convenient way to connect multiple devices
into the same small network uses a device called
a Local Area Network (LAN) switch. The term Local
Area Network simply refers to the idea that the
computers sit near each other (local). To create
this kind of small network, connect each
computers NIC to a cable, and connect the other
end of the cable to the LAN switch.
Figure 2-29
A Simple Lab Network All Computers Connect to
One Switch (Node)
33
34Wireless Networking
- Wireless networking Uses radio waves to
communicate. - Example Home-based network with multiple
devices. - Each device creates link to switch using cables
(wires) or radio frequency (wireless) to send
bits to each other. - Bits first go to switch, then toreceiving device.
Figure 2-30
A Home Network Using Wired (Cabled) and Wireless
34
35Uncovering the Network Between the Application
Endpoints
- Enterprise Networks Use Wide Area Networks
(WANs) to connect various remote sites together. - Network designers prefer routers to connect
sites using WAN links, as routers can connect
to both WAN links and LAN switches.
Bits that represent the customer account number
flow over the LAN link to the Boston switch,
then over the LAN link to the Boston router,
then over the WAN link to the headquarters
router, then over the short LAN link to the first
floor switch, and so on.
Figure 2-32
Multiple Sites in an Enterprise with Routers
35
36Summary This chapter
- Began by focusing on the parts of networking that
the average person uses apps on typical consumer
electronics and computing devices. - Introduced the hidden concepts and terms of
networking while using those familiar topics to
ease the process. - Sketched out how web protocols work so that a
users Web browser requests a Web page, and how
the Web server responds to supply that Web page. - Explained how Web server software, running on
some computer hardware, uses the network between
the computers to send a Web page to a users
computer.
36
37Lab Activities
- Complete lab activities on Chapter 2
- Lab 2.1 Connecting Computers
- Lab 2.2 Network Drivers
- Lab 2.3 Network Types and Topologies
- Lab 2.4 Command line interface