book

Cisco Networking Simplified, Second Edition

Name: Cisco Networking Simplified, Second Edition
ISBN: 9781587056017

by Jim Doherty, Neil Anderson, Paul Della Maggiora

December 2007

Intermediate to advanced

432 pages

9h 36m

English

Cisco Press

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Copyright
Dedications
About the Technical Reviewers
Acknowledgments
Introduction
What’s New in This Edition?So How Do I Use This Thing?
I. Networking Fundamentals
How Computers Communicate
The OSI ModelOpen Versus Proprietary SystemsSeven LayersAt-a-Glance: OSI ModelWhy Should I Care About the OSI Model?OSI Layers and DefinitionsWhat Problems Need to Be Solved?Communicating Between LayersEncapsulationDe-encapsulationExtra Layers?Internet Infrastructure: How It All Connects
TCP/IP and IP Addressing
Computers Speaking the Same LanguageWhat Is an Address?Dynamically Allocated IP AddressesDomain Names and Relationship to IP AddressesMatching Domain Names to IP AddressesAt-a-Glance: TCP/IPWhy Should I Care About TCP/IP?What Problems Need to Be Solved?TCP/IP DatagramsHow TCP Connections Are EstablishedTCP WindowingUDPPort NumbersHistory of TCP/IPAt-a-Glance: IP AddressingWhy Should I Care About IP Addressing?What Problems Need to Be Solved?Logical Versus PhysicalAddress ClassesSubnettingSubnet MasksIdentifying Subnet AddressesAt-a-Glance: IPv6Why Should I Care About IPv6?What Problems Need to Be Solved?IPv6 AddressesIPv6 NotationIPv6 AutoconfigurationIPv6 SecurityIPv6 MobilityIPv6 TransitionNAT and PAT
Internet Applications
The Internet and Its ApplicationsE-MailE-Mail ToolsWhat’s Up with the @ Sign?Sending E-MailsReceiving E-MailsWeb BrowsingWhat Are HTTP and HTML, and What Do They Do?E-MailPeer-to-Peer Sharing
II. Networking Infrastructure
Ethernet
History of EthernetWhat Is Ethernet?Evolution of EthernetAt-a-Glance: EthernetWhy Should I Care About Ethernet?What Problems Need to Be Solved?Ethernet CollisionsSmaller SegmentsIncreasing BandwidthEthernet SegmentsHubsRepeatersBridgesSwitched EthernetLAN RoutersWhat They Gave AwayReducing Collisions on Ethernet

LAN Switching
Fast Computers Need Faster NetworksSwitching Basics: It’s a BridgeSwitching EthernetsSwitches Take Over the WorldAt-a-Glance: SwitchingWhy Should I Care About Switching?What Problems Need to Be Solved?Broadcast and Collision DomainsForwarding and FilteringAddress LearningFrame Transmission ModesVirtual LANs (VLAN)
Spanning Tree
Network LoopsSometimes, the Earth Is FlatPreventing Network LoopsSpanning-Tree FundamentalsAt-a-Glance: Spanning TreeWhy Should I Care About Spanning Tree?What Problems Need to Be Solved?Problems with LoopsBroadcast StormsMultiple Copies of the Same FrameMAC Address Table InstabilityHow Spanning Tree WorksPort RolesPort StatesAssessing the Health of LinksRecalculating PathsReflections on Spanning Tree
Routing
RoutersRouters Talk Among Themselves to Find RoutesRouters Route PacketsRouters Bridge and Switches RouteAt-a-Glance: RoutingWhy Should I Care About Routing?What Problems Need to Be Solved?What Exactly Does “Best” Mean?Static Versus DynamicFlat Versus HierarchicalIntradomain Versus InterdomainDistance Vector Versus Link-StateHow Information Is Discovered with Distance VectorsLink-State RoutingRouting and Switching
III. Network Design
Campus Networks and Hierarchical Design
Building Networks for Ease of UseAt-a-Glance: Hierarchical Campus DesignWhy Should I Care About Campus Design?Campus Design Best PracticesHigh AvailabilityOversubscriptionRedundancyCampus Size Design ConsiderationsSmall CampusMedium CampusLarge CampusCampus Services
WAN Network Design
Moving Traffic Across the Street and the WorldWAN ServicesIntegrated Services Digital NetworkFrame RelayATMMPLSBroadbandVirtual Private Networks (VPN)WAN DevicesAt-a-Glance: Frame RelayWhy Should I Care About Frame Relay?What Problems Need to Be Solved?Frame Relay EquipmentVirtual CircuitsSwitched Virtual Circuit (SVC)Permanent Virtual Circuit (PVC)Local Management Interface (LMI)Data Link Connection IdentifierCongestion NotificationPerformanceAt-a-Glance: Asynchronous Transfer Mode (ATM)Why Should I Care About ATM?What Problems Need to Be Solved?ATM DevicesATM Network InterfacesATM FeaturesAsynchronous TransmissionFixed Cell SizeATM ConnectionsVirtual ConnectionLAN Emulation (LANE)Multiprotocol Label Switching (MPLS) ServicesAt-a-Glance: MPLSWhy Should I Care About MPLS?What Problems Need to Be Solved?Equipment and StuffMPLS LabelsMPLS SecurityMPLS ArchitectureHow Does the Router Know Where to Send Stuff?Other MPLS FeaturesMPLS Traffic Separation
Broadband Technologies
Always-on AccessBroadband Technology EvolutionCable ModemDSLWhich One Is Better?At-a-Glance: ISDNWhy Should I Care About ISDN?What Problems Need to Be Solved?ISDN and Internet AccessISDN Standard Access MethodsMaking an ISDN CallISDN Device Types and Reference PointsService Provider Identifiers (SPID)At-a-Glance: BroadbandWhy Should I Care About Broadband?What Problems Need to Be Solved?The Need for SpeedDigital Subscriber Line (DSL)DSL EquipmentLimitations and AdvantagesCableCable EquipmentLimitations and Advantages
Virtual Private Networks
Secure Networking Over the InternetAt-a-Glance: VPNsWhy Should I Care About VPNs?What Problems Need to Be Solved?Deployment ModesVPN ArchitectureGeneric Routing Encapsulation (GRE)IPsecVPN ArchitectureDynamic Multipoint VPNs (DMVPN)MPLSEstablishing a VPN ConnectionAt-a-Glance: EncryptionWhy Should I Care About Encryption?What Problems Need to Be Solved?Bullets, Bombs, and Secret CodesData Encryption Standard (DES)Triple Data Encryption Standard (3DES)Advanced Encryption Standard (AES)Using Keys to Encrypt StuffDiffie-Hellman Key ExchangeWhere You Encrypt MattersClient Authentication
Optical Technologies
LANs, WANs—and Now MANsSONET, DWDM, and DPTAt-a-Glance: Metro OpticalWhy Should I Care About Metro Optical?What Problems Need to Be Solved?Fiber BasicsKey Design CriteriaMultiplexingOptical EthernetCWDMDWDMSONET
Branch Office Network Designs
Distributed WorkforceDistributed Office ChallengesAt-a-Glance: Branch Office DesignWhy Should I Care About Branch Office Design?What Problems Need to Be Solved?Architecting a Branch NetworkScaling the BranchCritical Design Questions to AnswerBranch SecurityCritical Security Questions to AnswerBranch CommunicationCritical Communication Questions to Answer
IV. Network Availability
High Availability
At-a-Glance: High AvailabilityWhy Should I Care About High Availability?What Affects Network Availability?How Is Availability Measured?Best PracticesReducing Network ComplexitySoftware AvailabilityLink/Carrier AvailabilityClean Implementation/Cable ManagementNetwork MonitoringNetwork/Server RedundancyTrainingChange Control ManagementSecurity Posture and Policies
Control Plane
When Good Networks Go BadControl Plane ProtectionAt-a-Glance: Control Plane ProtectionWhy Should I Care About Control Plane Protection?What Problems Need to Be Solved?How Does Control Plane Protection Work?Control Plane PolicingDedicated CPUs
Quality of Service and Network Availability
Quality of Service as Network Protection?Scavenger QoSAt-a-Glance: QoS for Network ResiliencyWhy Should I Care About QoS for Network Resiliency?QoS BasicsQoS: Protecting the Good, Dumping the BadWhat Is “Normal”?Don’t Go It AloneDefining Scavenger Traffic/Normal TrafficFirst-Order Traffic AnomaliesSecond-Order Traffic Anomaly
Disaster Recovery
What Happens When the Network Stops WorkingDR PlanningResiliency and Backup ServicesPreparedness TestingAt-a-Glance: Disaster Recovery: Business ContinuanceWhy Should I Care About Disaster Recovery?What Are Typical Causes of Disasters?Natural DisastersUnintentional Man-Made DisastersIntentional Man-Made DisastersWhat Problems Need to Be Solved?Before a Disaster OccursRisk AssessmentPlanning for a DisasterBacking Up SystemsPreparedness TestingAfter a Disaster OccursRecovery to Normal OperationsRestoring Primary SystemsDisaster Recovery
Network Management
Keeping the Network Alive from AfarNetwork Documentation: A Must-HaveNetwork-Management ProtocolsTroubleshooting ToolsAt-a-Glance: Network ManagementWhy Should I Care About Network Management?What Problems Need to Be Solved?Nightmare of MobilityNetwork Management
V. Securing the Network
Network Security
IdentityPerimeter SecurityData PrivacySecurity MonitoringPolicy EnforcementAt-a-Glance: Network SecurityWhy Should I Care About Network Security?What Problems Need to Be Solved?Balancing Trust Versus SecurityEstablishing IdentityPerimeter SecurityData PrivacySecurity MonitoringPolicy EnforcementAt-a-Glance: HackingWhy Should I Care About Hacking?What Problems Need to Be Solved?Hacks and AttacksInside JobsRogue Access PointsBack DoorsDenial of Service (DoS)Anarchists, Crackers, and KiddiesViruses and WormsTrojan HorsesBotnetsSniffing/SpoofingDoS AttacksSnooping and Spoofing
Firewalls
Protecting the PerimeterGet Off the Net!Firewall for Your ProtectionPersonal FirewallsAt-a-Glance: Firewalls and IDSWhy Should I Care About Firewalls and IDS?What Problems Need to Be Solved?What Does a Firewall Do?Are You a Good Packet or a Bad Packet?Clean NetInside FilterIsolation LANOutside FilterThe Dirty NetHackers and Their Evil WaysFirewalls and IDSAccess and Content Security
Intrusion Prevention Systems
Intrusion Detection SystemsIntrusion Prevention SystemsThe Problem with False PositivesAt-a-Glance: Intrusion DetectionWhy Should I Care About Intrusion Detection?What Problems Need to Be Solved?Where Can IDS Be Deployed?Passive MonitoringActive MonitoringSneak Attacks
Port-Based Security
Combating Access-Based AttacksAt-a-Glance: Port-Based SecurityWhy Should I Care About Port-Based Security?What Problems Need to Be Solved?Where Port Security FitsMAC FloodingMalicious DHCP ServerARP Poisoning/SpoofingSpoofed IP Addresses
Identity-Based Networking
Network Access ConundrumIdentity-Based Networking802.1xAt-a-Glance: IdentityWhy Should I Care About Identity?What Problems Need to Be Solved?What the Heck Is 802.1x?Extensible Authentication Protocol (EAP)What Does Identity Do for Me?Preventing Unwanted AccessLimiting Access to Networked ResourcesUser-Based Service ProvisioningWorking with Authentication ServersRADIUSPKIAuthentication
Network Admission Control
Combating Virus OutbreaksAssessing Device “Health”Network Admission ControlAt-a-Glance: NACWhy Should I Care About Network Admission Control?What Problems Need to Be Solved?What Does NAC Do, Exactly?Appliance-Based Cisco Clean AccessNetwork-Based Cisco NAC Framework
URL Filtering: Eliminating Unwanted Web Page Access
Internet Access and Liability IssuesEnforcing Corporate Internet Usage PoliciesAt-a-Glance: URL FilteringWhy Should I Care About URL Filtering?What Problems Need to Be Solved?How URL Filtering WorksUsing Black/White ListsUsing Third-Party ServersURL Filtering and Firewalls
Deep Packet Inspection: Controlling Unwanted Applications
How Do You Catch a Criminal When Everyone Wears a Mask?Deep Packet InspectionAt-a-Glance: Deep Packet InspectionWhy Should I Care About Deep Packet Inspection?What Problems Need to Be Solved?How Does It Work?Catalyst ExamplePacket Inspection
Telemetry: Identifying and Isolating Attack Sources
Normal or AbnormalUsing Telemetry to Combat AttacksAt-a-Glance: TelemetryWhy Should I Care About Telemetry?What Problems Need to Be Solved?What Does Telemetry Do?Anomaly DetectionSource Location Using TracebackMitigation/Reaction
Physical Security: IP Video Surveillance
Locks on the DoorsVideo SurveillanceAt-a-Glance: Physical SecurityWhy Should I Care About Physical Security?What Problems Need to Be Solved?Digital Systems OverviewIP-Enabled Video SystemsBells and WhistlesPhysical and Logical Security
VI. Data Centers and Application Networking
Data Centers
Store Once, Use Oftenn-Tier ModelFunctions and RequirementsAt-a-Glance: Data CentersWhy Should I Care About Data Centers?What Problems Need to Be Solved?Types of Data CentersData Center LayersDistribution (n-Tier Model)Traditional Client/Server Versus n-TierData Center FacilitiesStorage MethodsData Center ManagementSecurity ServicesData Center Application: Corporate Expense System
Storage Area Networks
Efficient Deployment of Critical DataFiber Channel and IPInfinibandAt-a-Glance: Storage NetworkingWhy Should I Care About Storage Networking?What Problems Need to Be Solved?What Is Storage Networking?Traditional Server-Centric Storage MethodsStorage Networking TechnologiesSmall Computer Systems Interface (SCSI)Fiber ChannelInternet Small Computer Systems Interface (iSCSI)Serial Advanced Technology Attachment (SATA)Retrieval MethodsNetwork Attached Storage (NAS)Storage Area Network (SAN)Server-Centric Storage
Caching
Moving Content Close to the UserHow Caching WorksCaching More Than Web PagesStorage Caching: From Disk to MemoryIssues Affecting CachingCaching
Wide Area File Services
Branch Offices RuleCentralizing StorageEnter Wide Area File Services (WAFS)At-a-Glance: Wide Area File ServicesWhy Should I Care About Wide Area File Services?What Problems Need to Be Solved?How Cisco WAFS WorksEnsuring TransparencyFile System TransparencyCachingFile Caching
Wide Area Application Services
Centralizing ApplicationsEnter Wide Area Application Services (WAAS)At-a-Glance: Wide Area Application ServicesWhy Should I Care About Wide Area Application Services?What Problems Need to Be Solved?How Wide Area Application Services WorksTransparencyWAFS Uses Mapped TCP FlowsTCP CompatibilityDRETCP Flow Optimization (TFO)Data Redundancy Elimination (DRE)
VII. Unified Communications
Voice over IP
Making Calls over the WebUnifying CommunicationsClient LayerInfrastructure LayerCall-Processing LayerApplication LayerDeployment ModelsAt-a-Glance: Voice over IPWhy Should I Care About Voice over IP?What Problems Need to Be Solved?Converting Analog Voice Signals to Digital PacketsTransporting Packets in Real TimeAnalog Voice-to-Digital ConversionCompressing VoiceComfort NoiseVoice over IPAt-a-Glance: Unified CommunicationsWhy Should I Care About Unified Communications?What Problems Need to Be Solved?Explaining Toll BypassMaking a Call on an IP PhoneThe Big PictureClient LayerCall Processing LayerApplication LayerInfrastructure LayerVoice over IP: Toll Bypass
Quality of Service
Converged Networks and QoSWhat Is QoS?QoS and Unified CommunicationsAt-a-Glance: QoSWhy Should I Care About QoS?What Problems Need to Be Solved?The Three EvilsThree Steps to QualityLow-Bandwidth ToolsHow Packets Are Prioritized
Unified Personal Communications
Too Many Communications, Too Little TimeUnify MeCisco Unified Personal Communicator (CUPC)At-a-Glance: Unified CommunicationsWhy Should I Care About Unifying Communications?What Problems Need to Be Solved?How Unifying Communications WorksReach out and Touch SomeoneManagement CapabilitiesIncreased Productivity
Meeting Collaboration Spaces
Meetings, Meetings, MeetingsMeetings Are an Activity, Not a PlaceAt-a-Glance: Meeting CollaborationWhy Should I Care About Meeting Collaboration?What Problems Need to Be Solved?How Does It Work?Working with What You HaveVideoconferencingPresence and Instant Messaging
Traditional Videoconferencing
I See YouVideo over IP NetworksAt-a-Glance: IP VideoconferencingWhy Should I Care About Videoconferencing?What Problems Need to Be Solved?Videoconferencing EquipmentH.323T.120ZonesSingle ZonesMultiple ZonesVideoconferencingVideoconferencing Application E-Learning
Telepresence
Conferencing Gets SimpleVideo Killed the Radio StarThe Next-Best Thing to Being ThereAt-a-Glance: TelepresenceWhy Should I Care About Telepresence?What Problems Need to Be Solved?What Does Telepresence Do?IT FurnitureTelepresence over IPQoS RequiredMultipoint Connections
Presence and Location-Aware Services
I Sense a PresenceThe Importance of LocationAt-a-Glance: Presence and Location-Aware ServicesWhy Should I Care About Presence and Location-Aware Services?What Problems Need to Be Solved?How It WorksPresent and Accounted ForLet’s Go Live
IP Call Center
Why Can’t I Talk to a Real Person?Anatomy of a Contact CenterFrom the Caller to the Agent, and Back AgainManaging Caller and Contact Agent EfficiencyNew Methods for Customer InteractionAt-a-Glance: IP Contact CenterWhy Should I Care About IP Contact Center?What Problems Need to Be Solved?IPCC EquipmentTwo Simple Call Flow ExamplesOther Cool StuffCall-Center Tech SupportCall-Center Telemarketing
Multicast and IPTV Broadcasts
Watching Movies Without Flooding the WorldAt-a-Glance: IP MulticastWhy Should I Care About IP Multicast?What Problems Need to Be Solved?Internet Group Management Protocol (IGMP)Multicast Distribution TreesLayer 2 MulticastCisco Group Management Protocol (CGMP)IGMP SnoopingMulticast ForwardingProtocol-Independent Multicast (PIM)Multicast
VIII. Mobility
Mobility and Wireless Networks
Throwing Away the Ties That BindAt-a-Glance: Wireless LANsWhy Should I Care About Wireless LANs?What Problems Need to Be Solved?In Building SystemsWLAN RoamingBuilding-to-Building Bridge SystemsSecurity Issues and OptionsWired LANsWireless LANs
Selecting and Building Wireless Networks
Designing a Wireless NetworkAt-a-Glance: Designing Wi-Fi NetworksWhy Should I Care About Wireless Design?What Problems Need to Be Solved?Cisco Unified Wireless SolutionWireless StandardsWireless Network DesignsWLAN RF Coverage Site SurveyEffects of Lowering WLAN AP RF PowerPortability Versus Mobility
Securing Wireless Networks
Locking Down WirelessBalancing Security and AccessAt-a-Glance: Securing Wi-FiWhy Should I Care About Wireless Security?What Problems Need to Be Solved?Securing Wireless NetworksWireless EncryptionHealth ChecksRogue Access Points
Outdoor and Municipal Wireless Networks
It’s Just Like a Building, Only Way BiggerAt-a-Glance: Municipal Wi-FiWhy Should I Care About Municipal Wireless?What Problems Need to Be Solved?High-Level DiagramWireless Mesh DeploymentMuni Access PointsWireless BackhaulWireless BackhaulSecurity
VoIP over Wireless Networks
Wireless VoIPAt-a-Glance: Wireless VoIPWhy Should I Care About Wireless VoIP?What Problems Need to Be Solved?Integrating Cisco Wireless Networks with Unified CommunicationsCoverage and QualityPacket LossQoS for Wireless VoIPManaging Call Capacity per APWireless VoIP
Wireless Guest Access
Mi Casa Es Su CasaAt-a-Glance: Wireless Guest AccessWhy Should I Care About Wireless Guest Access?What Problems Need to Be Solved?Providing Wi-Fi Guest AccessWireless Guest Access DesignGuest SSIDGuest Access: Step by Step
RFID and Location-Based Services
Finding Your StuffWireless LANS: They’re Not Just for Checking E-Mail on the Toilet Anymore!At-a-Glance: Location-Based ServicesWhy Should I Care About Wireless Location Services?What Problems Need to Be Solved?Radio Frequency Identification (RFID) TechnologiesUnified Wireless and Location Services ArchitecturePlanningCisco Unified Wireless Architecture Including Location ServicesMonitoring Asset LocationWireless Location Services
IX. Virtualized Networks
Virtualizing Data Centers
Growth of the Data CenterData Center VirtualizationAt-a-Glance: Virtual Data CentersWhy Should I Care About Virtual Data Centers?What Problems Need to Be Solved?Data Center VirtualizationFixed Versus VirtualData Center Migration
Virtualizing Network Infrastructure
Leveraging Network InvestmentA Network Is a NetworkVirtualizing Network InfrastructureAt-a-Glance: Virtual Network InfrastructureWhy Should I Care About Virtual Networks?What Problems Need to Be Solved?High-Level DiagramThree-Part FrameworkAuthentication and IsolationPartitions Across the WAN
Applications of Virtualized Networks
What Can You Do with Virtualized Networks?Corporate Employee “Clean” and “Dirty” NetworksGuest and Partner NetworksIsolating Specialized Devices and ApplicationsLoad BalancingProviding Hosted Networks to Entities Within EntitiesDepartmental Virtual NetworksChallenges with Virtual NetworksAt-a-Glance: Virtualized Network ApplicationsWhy Should I Care About Virtualized Network Applications?What Problems Need to Be Solved?High-Level DiagramNetwork Admission ControlGuest and Partner AccessDevice IsolationEvolution of Virtual Networks
About the Authors

Content preview from Cisco Networking Simplified, Second Edition

Chapter . Spanning Tree

Network Loops

With increased reliance on the network, many companies wanted redundancy built into their switched networks. In the event of a failure, alternative paths could still be used to switch and forward packets. One drawback of this approach is that network loops can occur. Loops form when redundant connections between switches form a circular path. This leads to a condition in which the same packets can travel endlessly around the same path in a circle.

Loops can be deadly, bringing whole networks to a halt, especially when IP services such as multicast and broadcast are enabled. Because of this possibility, it is always a good practice to break up Layer 2 networks with Layer 3 routers.

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