icnd_s1m01_exploring the functions of networking

8/12/2019 ICND_S1M01_Exploring the Functions of Networking

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Building A Simple

Network

Exploring the Functions of Networking


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Objectives

What Is a Network? Components, Resource-SharingFunctions and Benefit, Characteristics of a Network,

Explain the Physical Versus Logical Topologies

Explain the Connection to the Internet.


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What Is a Network?


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Enterprise:

Main Office

Remote Local

Branch office

Home Office

Mobile users


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Common Physical Components of a Network

1. Personal computers (PCs)

2. Interconnections

3. Network Devices

4. Protocols


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1. Personal computers (PCs): The PCs serve asendpoints in the network, sending and receiving data.

2. Interconnections:

Network interface cards (NICs):

Network media, such as cables or wireless media,

Connectors

3. Network Devices:

Hubs:

Switches:

Routers:

Firewall:

4. Protocols: Ethernet, TCP/IP, DHCP, ARP,

Common Physical Components of a Network


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Interpreting a Network Diagram


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Resource-Sharing Functions and Benefits

Data and applications

Resources

Network storage: DAS, NAS, SAN

Backup devices


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Network User Applications

E-mail: E-mail is a valuable application for most network users.Users can communicate information (messages and files)electronically in a timely manner, to not only other users in thesame network but also other users outside the network (Outlook,POP3, Yahoo, and so on)

Web browser:A web browser enables access to the Internetthrough a common interface. The Internet provides a wealth ofinformation and has become vital to the productivity of both homeand business users (IE, Firefox, and so on)

Instant messaging: Instant messaging started in the personal

user-to-user space; however, it soon provided considerablebenefit in the corporate world (Yahoo IM, Microsoft Messenger,and so on)

Collaboration: (Whiteboard, Netmeeting, WebEx, and so on)

Databases: (file servers)


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Impact of User Applications on the Network

Batch applications

FTP, TFTP, inventory updates

No direct human interaction

Bandwidth important, but not critical

Interactive applications Inventory inquiries, database updates.

Human-to-machine interaction.

Because a human is waiting for aresponse, response time is importantbut not critical, unless the wait

becomes excessive.

Real-time applications

VoIP, video

Human-to-human interaction

End-to-end latency critical


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Characteristics of a Network1. Speed: Speed is a measure of how fast data is transmitted over the

network. A more precise term would be data rate

2. Cost: indicates the general cost of components, installation, andmaintenance of the network

3. Security: indicates how secure the network is, including the data that istransmitted over the network. The subject of security is important and

constantly evolving.

4. Availability: is a measure of the probability that the network will beavailable for use when required.

5. Scalability: indicates how well the network can accommodate more usersand data transmission requirements. If a network is designed and optimized

for just the current requirements, it can be very expensive and difficult tomeet new needs when the network grows

6. Reliability: indicates the dependability of the components (routers,switches, PCs, and so on) that make up the network

7. Topology: Networks have two types of topologies: the physical topology

and the Logical topology


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Physical Topology Categories


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Logical Topologies


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Bus Topology

All devices receive the signal.


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Star Topology

Transmission through a central point.

Single point of failure.


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Extended-Star Topology

More resilient than star topology.


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Ring Topology

Signals travel around ring.

Single point of failure.


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Dual-Ring Topology

Signals travel in opposite directions.

More resilient than single ring.


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Full-Mesh Topology

Highly fault-tolerant

Expensive to implement


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Partial-Mesh Topology

Trade-off between fault tolerance and cost


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Connection to the Internet


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Summary

A network is a connected collection of devices that cancommunicate with each other. Networks carry data in many kindsof environments, including homes, small businesses, and largeenterprises.

There are four major categories of physical components in acomputer network: the computer, interconnections, switches, androuters.

Networks are depicted graphically using a set of standard icons.

The major resources that are shared in a computer networkinclude data and applications, peripherals, storage devices, andbackup devices.

The most common network user applications include e-mail, webbrowsers, instant messaging, collaboration, and databases.

User applications affect the network by consuming networkresources.


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The ways in which networks can be described includecharacteristics that address network performance and structure:speed, cost, security, availability, scalability, reliability, andtopology.

A physical topology describes the layout for wiring the physicaldevices, while a logical topology describes how information flowsthrough a network.

In a physical bus topology, a single cable effectively connects allthe devices.

In a physical star topology, each device in the network isconnected to the central device with its own cable.

When a star network is expanded to include additional networkingdevices that are connected to the main networking device, it iscalled an extended-star topology.

Summary (Cont.)


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Summary (Cont.)

In a ring topology, all the hosts are connected in the form of a ringor circle. In a dual-ring topology, there are two rings to provideredundancy in the network.

A full-mesh topology connects all devices to each other; in a

partial-mesh topology, at least one device has multipleconnections to all other devices.

There are three common methods of connecting the small officeto the Internet: DSL using the existing telephone lines, cableusing the CATV infrastructure, and serial links using the classic

digital local loops.

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