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Chapter 1 : Exploring the network

Upon completion of this chapter you will be able to:

  1. Explain how networks affect the way we interact, learn, work and play.
  2. Describe how networks support communication.
  3. Explain the concept of a converged network.
  4. Describe the four basic requirements of a reliable network.
  5. Explain the use of network devices.
  6. Compare the devices and topologies of a LAN to the devices and topologies of a Wan.
  7. Explain the basic structure of the internet.
  8. Explain how LANs and WANs interconnect to the internet.
  9. Describe the impact of BYOD, online collaboration, video and cloud computing on a business network.
  10. Explain how networking technologies are changing the home environment.
  11. Identify some basic security threats and solutions for both small and large networks.
  12. Explain how the three Cisco enterprise architectures work to meet the needs of the evolving network environment.

1.0 Exploring the Network Class Activity – Draw Your Concepts of the Internet

Figure here says that Technology helps create a world which National borders, Geographic distances, Physical limitations Become less relevant to our daily lives.

1.1 Globally Connected> 1.1.2 Providing Resources in a Network

1.1.2 Providing Resources in a Network > Networks of Many Sizes

The figure gives you an idea about different type of network in terms of range

  • Small Home Networks connect a few computers to each other and the Internet.
  • Small Office/Home Office networks or SOHO network enables computers within a home office or a remote office to connect to a corporate network or access to centralized, shared resources.
  • Medium to large networks, such as those used by corporations and schools, can have many locations with hundreds or thousands of interconnected computers.
  • World Wide Networks, the internet is a network that connects hundreds of millions of computers world-wide.

1.1.2 Providing Resources in a Network > Clients and Servers

The figure here exhibits a star topology in which different clients and servers are connected to a switch. The different client and server services are briefly described below.

  • Web Client and Server

The web server runs server software and clients use their browser software, such as Windows Internet Explorer, to access web pages on the server.

  • Email Client and Server

The Email Server runs server software and clients use their mail client software, such as Microsoft Outlook, to access Email on the server.

  • File Client and Server

The File Server stores the file , the client device accesses the file with client software such as Windows Explorer.

1.1.2 Providing Resources in a Network > Clients and Servers (Cont.)

The exhibit in this page show four computers are connected to a single server which explain multiple types of server software and multiple types of client software running on a single computer.

 The server is an email server, web server and file server.

The first computer is a File Access Client.
2nd computer is a web browser as well as an email client.
3rd computer is a web browser and file access client.
4th computer is an email client also a file access client.

1.1.2 Providing Resources in a Network > Peer-to-Peer

The exhibit in this page show two computers and a printer connected in a single line which is a peer-to-peer network. Also there is a display of advantages and disadvantages of peer-to-peer networking. The Advantages of peer-to-peer networking:

  • Easy to setup
  • Less complexity
  • Lower cost since network devices and dedicated servers may not be required.
  • Can be used for simple tasks such as transferring files and sharing printers.

The disadvantages of peer-to-peer networking

  • No centralized administration
  • Not as secure
  • Not scalable
  • All devices may act as both clients and serves which can slow their performance.

1.2 LANs, WANS, and the Internet

1.2.1 Components of a network > End Devices

In the animation shown here has two LAN’s LAN1 and LAN2 connected by an Internetwork consisting of four routers connected to each other. A message from a user on LAN1 is sent to router1 on internetwork, from router1 it has three paths to travel by considering various conditions (which will be learned later) it choose path through router 2 and reaches LAN2.At LAN2 message is received by the switch and by checking the destination address of the message it is delivered to the user intended to receive the message. The description given in this animation is data originates with an end device, flows through the network, and arrives at an end device.

1.2.1 Components of a network > Intermediary network devices

In this animation there are four routers, which is an intermediary device, connected to each other.
In the first case a message arrives at a router1 it is an important message thus it is given priority to send.
In the second case a message is sent from one router 1 to next router 2 but the message was broken thus it was send again.
In the third case message is received at a router2 and it has two paths through router 3 and router 4 to reach its destination, router2 send the message to the path were it will arrive faster i.e. through router 3.
The description given in this animation is intermediary devices direct the path of data but do not generate or change the data content.

1.2.1 Components of a network > Activity- Network components representations and functions

Name the network component according to the function:

  1. Provides an interface between human network and communication network.
  2. Provides a connection for a host to the network and can connect multiple networks to form an internetwork.
  3. Provides a channel for messages to travel from source to destination.

1.2.2 LANs and WANs > Local Area Networks

The figure shown here is a representation of LAN network, here four end devices are connected to a single switch and switch is connected to a server. A network serving a home, building or a campus is considered a LAN.

1.2.2 LANs and WANs > Wide Area Networks

The picture represented here is a WAN, here two LANS are separated by geographic distance which is connected by a WAN. LANS separated by geographic distance are connected by a network known as WAN.

1.2.3 The Internet > The Internet

In the given figure different LANs and WANs are connected to each other that represent Internet. LANS and WANS maybe connected into internet.

1.2.3 The Internet > Intranet and Extranet

Three concentric circles are used in this figure to represent internet, intranet and extranet.
The innermost circle stands for intranet this represent company only.
The middle circle stands for extranet this represent suppliers, customers and collaborators.
The outermost circle correspond to internet this represent the world.

1.2.4 Connecting to the internet> Connecting remote users to the internet

The figure here illustrates the connection between small office and home users to internet service provider. The different connection options for above mentioned set-up are :

  • DSL
  • Cable
  • Cellular
  • Satellite
  • Dial-up Telephone

1.2.4 Connecting to the internet > Connecting Business to the Internet

The figure here illustrates the connection between organization and Internet service provider . The different connection options for this set-up are :

  • Dedicated leased line
  • Metro Ethernet
  • DSL
  • Satellite

1.3 The Network as a platform

1.3.1 Converged networks > The converging network

The two figures over here represents multiple networks and converged networks respectively. In figure 1three connections are shown here which represent multiple networks.

 First a PC is sending a message to another PC with the help of computer networks in the middle.
Second a message is send from a telephone to another telephone with telephone networks in the middle.
Third broadcasting station is connected to a television with broadcast networks in the middle.
These three different connection shows multiple services are running on multiple networks.
Figure 2 represent converged networks.
In figure 2 the above described separate and distinct communications forms in figure 1have converged onto a common platform.

All the end devices mentioned above are connected to other end devices with converged network in the middle. This figure depicts converged data networks carrying multiple services on one network.

1.3.1 Converged networks > Planning for the future

The pictures here represent how intelligent network represents are bringing the world together. Intelligent networks allow handheld devices to receive news and emails, and to send text.
Phones connect globally to share voice, text, and images.
Video conferencing around the globe is in the palm of your hand.
Online gaming connects thousands of people seamlessly.

1.3.2 Reliable Network> the supporting Network Architecture

The figures explain four characteristics network architecture should meet up. Figure 1 explains fault tolerance that is redundant connections allows for alternative paths if a device or link fails. The user experience is unexpected.
Figure 2 explains scalability that is additional users and whole networks can be connected to the internet without degrading the performance for existing users.
Figure 3 explains quality of service, managed by router; ensure that priorities are matched with the type of communication and its importance to the organization.
Web pages can usually receive a lower priority. Streaming media will need a priority to maintain a smooth uninterrupted user experience.
Figure 4 talks about security. Administrators can protect the network with software and hardware security and by preventing physical access to network devices.
Security measure protects the network from unauthorized access.

1.3.2 Reliable network> Fault tolerance in circuit switched networks

The figure explains a circuit switching in telephone network. Two telephones are connected by a number of telephone switches in between. Many paths are possible but only one path is selected per call. Once a call is established, all communication takes place on this path or circuit. A circuit is dedicated to this call for the duration of the call.The circuit stays active, even if no one is speaking.There are many, many circuits, but a finite number. During peak periods, some calls may be denied.

1.3.2 Reliable network> Fault tolerance is packet-switched networks

The figure demonstrates packet switching in a data network. In this network there are quite number of routers between the source and destination
In a packet switching network many paths maybe used for a single communication as individual packets are routed to a destination.
No fixed paths is established .Packets are routed according to the best path available at the time.
Prior to the transmission, each communication is broken into packets which are addressed and numbered.
Each packet has three blocks that is, source address, destination address and sequence number.
At the destination packets maybe reassembled into order according to their sequence number.
During peak periods, communication maybe delayed, but not denied.

1.3.2 Reliable network> Scalable networks

The figure explains the hierarchical nature of the network.

  • Tier- 1: This ISP’s are the backbone of the Internet. Examples are Verizon, Sprint, AT & T, NTT, cable systems, and wide area wireless networks. At the centre of the Internet, Tier-1 ISPs provide national and international connections .These ISP’s treat each other as equal.
  • Tier-2: This ISP’s are smaller and often provide regional services.Tier-2 usually pay Tier-1 ISPs for connectivity to the rest of the Internet.

Peer connections between networks at the same level provide direct connections, bypassing longer routes and preventing congestion on the backbone. The point where ISP’s interconnect is often called a border.

  • Tier-3: They are the local providers of the service directly to the end users .Tier-3 are usually connected to Tier 2 ISPs and pay Tier2 providers for internet access.

1.3.2 Reliable network> Providing QoS

Figure 1 explains different type of traffic and content carried by converged networks.

  • Real-time traffic such as voice over IP (VoIP) and video conferencing.
  • Web content like browsing and online shopping.
  • Transactional traffic that is order processing and billing, inventory and reporting, accounting and reporting.
  • Streaming traffic like Video on Demand (VoD) and movies.
  • Bulk traffic such as email, data backups, print files.

Figure 2 explain using queue to prioritize communication In the figure content from a telephone, a PC and web server is passed to a router. The contents are Voice over IP, financial transaction and web page respectively. Router prioritizes the three contents accordingly Voice Over IP is managed as high priority queue, financial transaction from PC is treated as medium priority queue and finally webpage is given low priority queue.
All the three communications are passed through a single link from router to the network .All communications has access to the media, but higher priority communication has greater percentage of the packets.
Queuing according to data type enables voice data to have priority over transaction data, which has priority over web data.

Figure 3 is tabling that compare communication type quality without QoS and with QoS.

Communication type Without QoS With QoS
Streaming audio or videoChoppy picture starts and stops Clear, continuous service.
Vital Transaction Time compared against price
  Time:02:14:05 Price: $1.54 Time:02:14:05 Price:$1.52
  Just one second earlier... The price maybe better
Downloading web pages(often low priority) Web page arrive a bit later But the end result is identical.

1.3.2 Reliable network> providing Network Security

The figure shows firewall, accessing policy and data encryption are important for security of a network. The communication and information that we would like to be private is protected from those who would make unauthorized use of it. Unauthorized use of our communications data can have severe consequences.

1.3.2 Reliable network> Activity – Reliable networks

Fill the table with appropriate characteristic or feature according to the network architecture requirement.

Requirements Feature or characteristic
Networks should be always available.  
Full memory queues means packets must be dropped.  
Priority queues are implemented when demand for network bandwidth exceeds supply  
Business and personal network equipment must be protected.  
Developing a plan for priority queuing is a strategy for quality delivery of information.  
Business and personal data must be protected  
Different type of Internet service providers can affect the quality of network data delivery.  
Networks can grow or expand with minimal impact on performance.  

1.4 The Changing Network Environment

1.4.1 Network Trends> New trends

Some predictions are written in this picture. They are:

  • By 2014, traffic from wireless devices will exceed traffic from wired devices.
  • By 2015, the amount of content traversing the Internet annually will be 540,000 times the amount that traveled in 2003.
  • By 2015, 90% of all content on the Internet will be video-based.
  • By 2015, a million video minutes will traverse the Internet every second.
  • By 2016, the annual global IP traffic will surpass the zettabyte threshold (1,180,591,620,717,411,303,424 bytes).
  • By 2016, the number of devices connected to IP networks will be nearly three times as high as the global population.
  • By 2016, 1.2 million minutes of video content will cross the network every second.
  • By 2020, 50 billion devices will be connected to the Internet.

There is video uploaded in this page which says about predictions. The video is uploaded by Cisco in YouTube which can be accessed from the link

1.4.1 Network Trends> Online collaboration

Benefits of incorporating collaboration tools into a business strategy include:

  • Improve customer satisfaction - Enhance the quality of customer experiences through an instant online presence and communication mechanism.
  • Increase communication choices - Provide a broader range of communication channels, while reducing cost and improving satisfaction.
  • Optimize team performance - Build trust and share information across distributed groups, businesses, and geographies to speed business agility.
  • Enable mobile users - Provide flexibility and satisfaction to employees by allowing them to work from anywhere, using any preferred device.
  • Improve organizational communications - Communicate effectively to the entire organization through online forums or company-wide online meetings that allow all company levels to participate and feel included.
  • Transform training and event management - Deliver an interactive strategy to achieving high business performance through training, without incurring additional travel costs of face-to-face interactions.
  • Improve facility management - Create a new workplace offering secure and flexible working options to improve teamwork, increase productivity, all while reducing the cost of real estate and physical workplace requirements.

1.4.1 Network Trends> Video Communication

Figure 1 is a graphical representation of trend of video in communication. It says in 2012 internet video accounts to 40% of all consumer internet traffic and it is expected in 2016 internet video will become 62%of all consumer Internet traffic.
Figure 2 give a text on drivers for implementing a video strategy:

  • A global workforce and need for real-time collaboration - Create collaborative teams that span corporate and national boundaries, and geographies.
  • Reducing costs and green IT - Avoiding travel reduces both cost and carbon emissions.
  • New opportunities for IP convergence - Converging video applications, such as high-definition video collaboration, video surveillance systems, and video advertising signage onto a single IP network.
  • Media explosion - Plummeting cost of video cameras and a new generation of high-quality, low-cost devices have turned users into would-be movie producers.
  • Social networking - The social networking phenomenon can be as effective in business as it is in a social setting. For example, employees are increasingly filming short videos to share best practices with colleagues, and to brief peers about projects and initiatives.
  • Demands for universal media access - Users are demanding to be able to access rich-media applications wherever they are, and on any device. Participation in video conferencing, viewing the latest executive communications, and collaborating with co-workers are applications that will need to be accessible to employees, regardless of their work location.

There is a video uploaded in this page about Cisco telepresence vision. It can be accessed from the link:

1.4.1 Network Trends> Cloud Computing

Figure 2 over here represents four types of clouds.

  1. Custom clouds: These are clouds built to meet the needs of specific industry such as healthcare or media. Custom clouds can be private or public.
  2. Hybrid clouds: A hybrid cloud is made up of two or more clouds (example: part custom, part public), where each part remains a distinctive object, but both are connected using a single architecture. Individuals on a hybrid cloud would be able to have degrees of access to various services based on user access rights.
  3. Private clouds: Cloud-based applications and services offered in a private cloud are intended for a specific organization or entity, such as the government. A private cloud can be set up using the organization’s private network, though this can be expensive to build and maintain. A private cloud can also be managed by an outside organization with strict access security.
  4. Public clouds: Cloud-based applications and services offered in a public cloud are made available to the general population. Services may be free or are offered on a pay-per-use model, such as paying for online storage. The public cloud uses the Internet to provide services.

1.4.1 Network Trends> Data Centers

The video tells about how big will be the cloud computing by 2015 .The link to the video

1.4.3 Network Security> Activity – Network Security Terminology

Fill the table with appropriate security terms.
The security terms can be chosen are firewall, Zero-day, Virus or Trojan horse, Access control list, Denial of service.

Terminology Definition
An attack which slows down or crashes equipments and programs.  
Filters network access and data traffic  
Blocks unauthorized access to your network  
Network attack that occurs on the first day that vulnerability becomes known.  
Arbitrary code running on user devices  

1.4.4 Network Architectures> CCNA

The picture shows the level of certifications in Cisco. Totally there are five levels they are: Level 1: Entry Level 2: Associate Level 3: Professional Level 4: Expert Level5: Architect

1.5 Summary

1.5.1 Summary> Class Activity –Draw your concepts for the Internet now


In this activity you will show how the concepts from chapter 1 are applied to show how network devices connect to and throughout the Internet. After reflecting on your home or small business topology, you will become familiar with the using device icons and knowledge used to visualize network connectivity through the remaining network courses.


In this activity you will use the knowledge you have acquired throughout the Chapter 1, and the modelling activity document that you prepared at the beginning of this chapter. You may also refer to the other activities completed in this chapter, including packet tracer activities. Draw a map of internet as you see it now. In your revised drawing you may need to include:

  • WANs
  • LANS
  • Cloud computing
  • Internet Service Providers(Tier)

Save your drawing in a hard copy format .Be prepared to share and explain your revised work in the class.

Required resources

  • Beginning of Chapter modelling activity drawing
  • Paper and Pencils or pens


After completing chapter 1, are you aware of more devices, cabling, and physical components of a small – to – medium sized network? Explain your answer.

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Page last modified on August 14, 2013, at 03:42 PM