Network+ Guide to Networks 5th Edition

1/28/20101/28/2010Network Plus

Troubleshooting and VOIP

Network+ Guide to Networks, 5th Edition4Troubleshooting Methodology (contd.)Troubleshooting stepsIdentify symptoms, problemsIdentify affected areaDetermine what has changedEstablish most probable causeDetermine if escalation necessaryCreate action plan, solutionImplement solution, test resultIdentify results, effectsDocument solution, process

Network+ Guide to Networks, 5th Edition18Hardware Troubleshooting ToolsUtilities help troubleshoot network problemsSpecialized tools Crossover cableButt SetTone GeneratorMultimeterCable Continuity testerTDROTDR

Software ToolsCommand line utilitiesIPCONFIG, Ping, TRACERT, NetStat, NSLookupNetwork MonitorNetwork adapter must support promiscuous modePlug into port configured for port mirroringCommon terms for abnormal data patterns, packetsLocal collisionsLate collisionsRuntsGiantsJabberGhosts

Software ToolsProtocol AnalyzerCaptures traffic, analyzes framesSniffer (packet sniffer) hardwareMay require Port Mirroring on switches to see all traffic. Only sees broadcasts and packets directed to the analyzer.Question 1When Jeff, a technician, is troubleshooting a problem, which of the following is the NEXT step after verifying full system functionality?A.Establish a plan of action to resolve the problem and identify potential effects.B.Implement the solution. C.Establish a theory of probable cause. D.Document findings, actions, and outcomes

Question 2Kim, a network technician, is troubleshooting a problem and has just established a plan of action to resolve the problem. Which of the following is the NEXT step in the troubleshooting methodology?A. Verify full system functionality and if applicable implement preventative measures.B.Implement the solution or escalate as necessary. C.Document findings, actions, and outcomes. D.Establish a theory of probable cause (e.g. question the obvious).

Question 3Lisa, a technician, is troubleshooting a cable problem. She has checked both ends and suspects an issue 50 yards (46 meters) from the location. Which of the following network tools will confirm this analysis?A.TDR B.Protocol analyzer C.Multimeter D.Cable crimper

Question 4A switch in IDF 3 has shut down at 3 p.m. everyday this week. Which of the following network tools should Kim, a technician, use to troubleshoot this problem?Environmental monitorCable TesterTDR Loopback plug

Question 5Which of the following tools would Lisa, a technician, BEST use to trace a wire through an area where multiple wires of the same color are twisted together?A.Cable tester B.Toner probe C.Cable crimper D.Punch down toolQuestion 6Zach, a technician, wants to test a laptop's NIC for functionality but has no other networking equipment to attach it to. Which of the following would allow him to test basic functionality of the NIC?A.Loopback plug B.Protocol analyzer C.Smart jack D.Coupler

Question 7Lisa, a network technician, is troubleshooting a new wireless network that has been dropping connections. She notices another wireless network in the area. Which of the following BEST explains the reason for the dropped connections?A. Latency B. SSID mismatch C. Interference D. Encryption typeQuestion 8Zach, a technician, suspects a duplicate IP address assignment on the network. Which of the following resources can be used to verify this problem?A. Network map B. Environmental monitor C. Placement map D. Syslog

Question 9Zach, a technician, discovers a switch is not communicating with the other switches in a stack. Which of the following is the MOST likely cause?A.Both T568A and T568B standards are being used.B.STP is disabled. C.The cable is not a crossover. D.The port is not trunked.

Question 10Kim, a network consultant, noticed that a new installation for a network backbone looked like this: ISP - Switch - Firewall - PC. Which of the following is the BEST configuration for a properly setup environment?A.Switch - ISP - Firewall PCB.ISP - Firewall - Switch - PC C.Firewall - ISP - PC - Switch D.ISP - PC - Firewall - Switch

VOIP Components

Network+ Guide to Networks, 5th Edition14Analog Telephone Attachment

Figure 11-4 Integrating VoIP networks and analog telephones

Network+ Guide to Networks, 5th Edition15Digital - IP TelephonesIP telephones (IP phones)Transmit, receive only digital signalsVoice immediately digitized, issued to network in packet formRequires unique IP addressLooks like traditional touch-tone phoneConnects to RJ-45 wall jackConnection may pass through connectivity device before reaching IP-PBX

SoftphonesComputer programmed to act like IP telephoneSoftphones and IP telephonesProvide same calling functionsConnect to network; deliver services differentlyPrerequisitesComputer minimum hardware requirementsIP telephony client installedDigital telephone switch communicationFull-duplex sound cardMicrophone, speakersExample: SkypeNetwork+ Guide to Networks, 5th Edition20

Network+ Guide to Networks, 5th Edition23

Figure 11-8 Connecting softphones to a converged network

Network+ Guide to Networks, 5th Edition37Signaling ProtocolsSignalingEstablish connectionInformation exchange Between network components, systemEstablishing, monitoring, releasing connectionsControlling system operationsSS7Protocol for handling call signaling in PSTN connectionsH.323 and SIP for VOIP

38H.323Supports voice, video-over-IP servicesH.323 componentsH.323 terminalH.323 gatewayH.323 gatekeeperMCU (multipoint control unit)H.323 zoneH.323 ProtocolsH.225 Application layer used for call setup signalingH.245 Session/presentation layer formattingLogical channels identified as port numbersOne channel for each direction (full duplex)

Network+ Guide to Networks, 5th Edition42SIP (Session Initiation Protocol)Performs similar H.323 functionsVersion 2.0 (RFC 2543)1999 IETF codifiedApplication layer signaling, multiservice control protocol, packet-based networksGoalsModeled on HTTP protocolReuse existing TCP/IP protocolsSession management, enhanced servicesModular and specific

Network+ Guide to Networks, 5th Edition43SIP (contd.)Similar purpose to H.323 More Limited capabilities and functionsDoes not supply caller ID SIP networkModeled on HTTPStandard maps out terms and architectureUser agentUser agent clientUser agent serverRegistrar serverProxy serverRedirect server

Network+ Guide to Networks, 5th Edition44SIP (contd.)

Figure 11-14 A SIP network

Network+ Guide to Networks, 5th Edition45SIP vs H.323SIP and H.323Regulate call signaling, control for VoIP or video-over-IP clients and serversDo not account for communication between media gatewaysVoIP vendors prefer SIP over H.323SimplicityFewer instructions to control callConsumes fewer processing resourcesAdapts easierMore flexible

46Media GatewaysGatewaysEnable converged networksConvert analog to digital signalsTranslate between SS7 and H.323/SIPMGCP (Media Gateway Control Protocol)MEGACOPerforms same functions as MGCP with different commands and processesOperates with H.323 or SIPSuperior to MGCPSupports ATM

Network+ Guide to Networks, 5th Edition48MGCP and MEGACO (contd.)

Figure 11-15 Use of an MGC (media gateway controller)

Transport ProtocolsUsed to deliver voice or video payloadTypically use UDP because less overheadRequire some additional delivery feedback information and method to provide for Quality of Service (QoS) in DeliveryDelivery Feedback ProtocolsRTPRTCPQoS ProocolsRSVPDiffServMPLS

Network+ Guide to Networks, 5th Edition51RTP (Real-time Transport Protocol)RFC 1889Operates at Application layerRelies on UDPApplies sequence numbers to indicate:Destination packet assembly orderPacket loss during transmissionAssigns packet timestampReceiving nodeCompensates for network delay, synchronize signalsNo mechanism to detect success

RTCP (Real-time Transport Control Protocol)Provides quality feedback to participantsPackets transmitted periodicallyWorks with RTPNot mandatory on RTP networksRTP and RTCPProvide information about packet order, loss, delayCannot correct transmission flaws52

53QoS (Quality of Service) AssuranceProtocols used to improve the packet switched VOIP or Video connection to make it more like a dedicated PSTN or Cable network.QoS measures how well a service matches its expected performance.HighDoes not experience interruptions, distortions, or broken communicationsLowMay experience communication problemsQoS protocolsRSVPDiffServMPLS

54RSVP (Resource Reservation Protocol)Transport layer protocolReserves network resources before transmission by creating path between sender, receiverIssues PATH statement via RSVP to receiving nodeTwo service typesGuaranteed serviceNo packet losses minimal delayControlled-load serviceType of service typical on low usage network

Network+ Guide to Networks, 5th Edition57DiffServAddresses traffic prioritization QoS issuesDiffers from RSVPModifies actual IP datagramAccounts for all network trafficTo prioritize trafficIPv4 datagram: DiffServ fieldIPv6 datagram: Traffic Class field

58DiffServ (contd.)Two forwarding typesEF (Expedited Forwarding)Data stream assigned minimum departure rateCircumvents delays by setting strict limits max 30 % of trafficAF (Assured Forwarding)Data streams assigned different router resource levelsPrioritizes data handling but provides not guarantee of On time, in sequence packet arrivalUses AF Classes to provide different service levels

Network+ Guide to Networks, 5th Edition59MPLS (Multiprotocol Label Switching)Modifies data streams at Network layerA first router data stream encountersReplaces IP datagram header with labelPacket forwarding informationRouters data stream path revises labelIndicates next hopConsiders network congestionVery fast forwarding: no delayDestination IP address compared to routing tablesForward data to closest matching node

Network+ Guide to Networks, 5th EditionNetwork+ Guide to Networks, 5th EditionThe End