NT1210 Introduction to Networking

1
NT1210 Introduction to Networking

• Unit 2
• Chapter 2, Introduction to Computer Networking

1
2
Objectives

• 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
3
Objectives

• 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
4
Computer 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
5
An 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
6
Data Communication System
7
Network 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

8
Overview of Network Components
Figure 1-1 Sample Computer Network
9
Defining 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)

11
Network Defined by Geography

• Local-area network (LAN)
• Wide-area network (WAN)
• Metropolitan-area network (MAN)
• Personal-area network (PAN)

12
Network 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

13
Client-Server Network
Figure 1-13 Client-Server Network Example
14
Peer-to-Peer Network
Figure 1-14 Peer-to-Peer Network Example
15
Network Defined by Topology
16
A bus topology connecting three stations
17
A ring topology connecting six stations
18
A star topology connecting four stations
19
A fully connected mesh topology (five devices)
20
A hybrid topology a star backbone with three
bus networks
21
Network 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

22
Email

• 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.

22
23
Sending 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.

23
24
Sending 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
25
Early 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
26
Early 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
27
Digital 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
28
Break
Take 10
28
29
A 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).

29
30
World 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
30
31
Web Servers (Hardware and Software)
Figure 2-18
Three Steps Web Server Sends Web Page into
Network
31
32
Uncovering 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
33
Local 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
34
Wireless 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
35
Uncovering 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
36
Summary 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
37
Lab 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