ICND110S01L01-The-Functions-of-Networking(ppt文档).ppt

2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-1Building a Simple NetworkExploring the Functions of Networking 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-2What Is a Network?2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-3Common Physical Components of a Network 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-4Interpreting a Network Diagram 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-5Resource-Sharing Functions and BenefitsData and applicationsResourcesNetwork storageBackup devices 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-6Network User ApplicationsE-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)2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-7Impact of User Applications on the NetworkBatch applications FTP,TFTP,inventory updatesNo direct human interactionBandwidth important,but not criticalInteractive applicationsInventory inquiries,database updates.Human-to-machine interaction.Because a human is waiting for a response,response time is important but not critical,unless the wait becomes excessive.Real-time applicationsVoIP,videoHuman-to-human interactionEnd-to-end latency critical 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-8Characteristics of a NetworkSpeedCostSecurityAvailabilityScalabilityReliabilityTopology 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-9Physical Topology Categories 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-10Logical Topologies 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-11Bus TopologyAll devices receive the signal.2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-12Star TopologyTransmission through a central point.Single point of failure.2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-13Extended-Star TopologyMore resilient than star topology.2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-14Ring TopologySignals travel around ring.Single point of failure.2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-15Dual-Ring TopologySignals travel in opposite directions.More resilient than single ring.2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-16Full-Mesh TopologyHighly fault-tolerantExpensive to implement 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-17Partial-Mesh TopologyTrade-off between fault tolerance and cost 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-18Connection to the Internet 2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-19SummaryA 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.Networks are depicted graphically using a set of standard icons.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.User applications affect the network by consuming network resources.2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-20The ways in which networks can be described include characteristics that address network performance and structure:speed,cost,security,availability,scalability,reliability,and topology.A physical topology describes the layout for wiring the physical devices,while a logical topology describes how information flows through a network.In a physical bus topology,a single cable effectively connects all the devices.In a physical star topology,each device in the network is connected to the central device with its own cable.When a star network is expanded to include additional networking devices that are connected to the main networking device,it is called an extended-star topology.Summary(Cont.)2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-21Summary(Cont.)In a ring topology,all the hosts are connected in the form of a ring or circle.In a dual-ring topology,there are two rings to provide redundancy in the network.A full-mesh topology connects all devices to each other;in a partial-mesh topology,at least one device has multiple connections to all other devices.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.2007 Cisco Systems,Inc.All rights reserved.ICND1 v1.01-22