01 Network basic

8/7/2019 01 Network basic

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2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.01-1

Building a Simple Network

Exploring theFunctions ofNetworking


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What Is a Network?


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Common Physical Components of aNetwork


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Interpreting a Network Diagram


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Resource-Sharing Functions andBenefits

Data and applications

Physical resources

Network storage

Backup devices


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Network User Applications

E-mail (Outlook, POP3, Yahoo, and so on)

Web browser (IE, Firefox, and so on)

Instant messaging (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 theNetwork

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 waitbecomes excessive.

Real-time applications

VoIP, video

Human-to-human interaction

End-to-end latency critical


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Characteristics of a Network

Speed

Cost

Security

Availability

Scalability

Reliability

Topology


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Physical TopologyCategories


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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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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 a

computer 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 apartial-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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