Mạng

1. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-1
Building a Simple Network
Exploring the
Functions of
Networking

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What Is a Network?

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Network Types
• Define Local Area Networks (LANs)
 A network serving a home, building or campus is considered a
Local Area Network (LAN)

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Network Types
• Define Wide Area Networks (WANs)
 LANs separated by geographic distance are connected by a
network known as a Wide Area Network (WAN)

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Network Types
• Define the Internet
 The internet is defined as a global mesh of interconnected
networks

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Common Physical Components of a
Network

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Describe network representations

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Resource-Sharing Functions and
Benefits
 Data and applications
 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)

10. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-10
Characteristics of a Network
 Speed
 Cost
 Security
 Scalability
 Reliability
 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 can
communicate with each other. Networks carry data in many kinds
of environments, including homes, small businesses, and large
enterprises.
 There are four major categories of physical components in a
computer network: the computer, interconnections, switches, and
routers.
 The major resources that are shared in a computer network
include data and applications, peripherals, storage devices, and
backup devices.
 The most common network user applications include e-mail, web
browsers, instant messaging, collaboration, and databases.

22. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—1-22
 A physical topology describes the layout for wiring the physical
devices, while a logical topology describes how information flows
through a network.
 There are three common methods of connecting the small office
to the Internet: DSL using the existing telephone lines, cable
using the CATV infrastructure, and serial links using the classic
digital local loops.
Summary (Cont.)

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