CH-12-13 Voice and Video over IP – Network+ Guide to Networks : Chapter Notes

This Document Contains Chapters 12 to 13 Chapter 12 Voice and Video Over IP At a Glance Instructor’s Manual Table of Contents • Overview • Objectives • Teaching Tips • Quick Quizzes • Class Discussion Topics • Additional Projects • Additional Resources • Key Terms Lecture Notes Overview Traditionally, separate networks served voice and data signals. In the last 15 years, telecommunications carriers, network service providers, data equipment manufacturers, and standards organizations have concentrated on ways to deliver voice, video, and data over the same networks. These converged networks, as they are called, may be cheaper and more convenient, but they also require new technology. This chapter describes a variety of voice and video-over-IP applications, plus the protocols and infrastructure necessary to deliver them. Chapter Objectives After reading this chapter and completing the exercises, the student will be able to: • Use terminology specific to converged networks • Explain VoIP (voice over IP) services, PBXs and their user interfaces • Explain video-over-IP services and their user interfaces • Describe VoIP and video-over-IP signaling and transport protocols, including SIP, H.323, and RTP • Understand QoS (quality of service) assurance methods critical to converged networks, including RSVP and DiffServ Teaching Tips Terminology 1. Define and describe IP telephony. a. Mention that IP telephony is more commonly known as VoIP (voice over IP). Teaching Tip Point out to the students that VoIP is pronounced “voip”. 2. Define the term VoATM (voice over ATM). 3. Define the term VoDSL (voice over DSL). 4. Emphasize that virtually any type of data connection can carry VoIP signals. 5. Define the term Internet telephony. 6. Point out that not all VoIP calls are carried over the Internet. 7. Describe the benefits of VoIP over private lines. 8. Point out that voice is not the only nondata application that can be carried on a converged network. 9. Describe FoIP (Fax over IP). 10. Briefly explain how IPTV (IP television) works. 11. Briefly describe videoconferencing. 12. Explain streaming video. a. Describe how webcasts are related to streaming video. 13. Review the concept of multicasting. 14. Review the concept of unified communications. VoIP (Voice over IP) Applications and Interfaces 1. Describe significant reasons for implementing VoIP. 2. Describe how voice and data can be combined on a network in several different configurations: a. A traditional telephone that sends and receives analog signals b. A telephone specially designed for TCP/IP transmission c. A computer equipped with a microphone 3. Note that on any VoIP network, a mix of these three types of clients is possible. Analog Telephones 1. Point out that if a VoIP caller uses a traditional telephone or if the entire VoIP connection is digital, voice signals still need to be converted from their natural, analog form into bits. 2. Describe the conversion process. 3. Describe four examples of analog-to-digital voice conversion techniques. a. Connect an analog telephone to a VoIP adapter (ATA (analog telephone adapter). b. Connect an analog telephone line to a switch, router, or gateway capable of accepting analog voice signals, converting them into packets, then issuing the packets to a data network - and vice versa. c. Use a digital PBX (private branch exchange). d. Use a traditional telephone connected to an analog PBX, which then connects to a voice-data gateway. 4. Use Figure 12-1 to illustrate an ATA (analog telephone adapter). 5. Use Figure 12-2 to illustrate a VoIP router. 6. Use Figure 12-3 to illustrate an IP-PBX capable of managing up to 60 calls at once. 7. Use Figure 12-4 to illustrate the four different ways analog telephones can be used to access a VoIP network. IP Telephones 1. Describe IP telephones. 2. Point out that in order to communicate on the network, each IP telephone must have a unique IP address. 3. Note that an IP telephone connects to an RJ-45 wall jack. 4. Use Figure 12-5 to illustrate how to access a VoIP network using IP phones. 5. Describe features IP telephones have in common with traditional telephones. 6. Describe benefits and features unique to IP telephones. 7. Explain one issue with IP telephones: a. Need for electric current 8. Use Figure 12-6 to illustrate a typical IP phone. Softphones 1. Define and describe a softphone. 2. Note that softphones and IP telephones provide the same calling functions. 3. Emphasize that softphones and IP telephones simply connect to the network and deliver services differently. 4. Describe the requirements that must be met before a computer can be used as a softphone. 5. Note that Skype, the popular Internet telephony software, is one type of softphone. 6. Use Figure 12-7 to illustrate a graphical representation of a telephone dial pad typically presented after a user starts the softphone client software. 7. Point out that softphones allow the user to customize his or her graphical interface. 8. Describe one difference between IP telephones and softphones. 9. Use Figure 12-8 to illustrate the use of softphones on a converged network. 10. Describe the advantages of softphones. Teaching Tip Provide an online demonstration of Internet telephony software by navigating to the Skype home page at http://www.skype.com and reviewing material and features available at the site. Quick Quiz 1 1. IP telephony, is the use of any network (either public or private) to carry ____________________ signals using the TCP/IP protocol. Answer: voice 2. True or False: VoIP can run over any packet-switched network. Answer: True 3. FoIP (Fax over IP) uses ____ networks to transmit faxes from one node on the network to another. a. bridged b. multipoint c. circuit switched d. packet-switched Answer: D 4. True or False: Mobility is a benefit of IP telephones. Answer: True 5. ____________________ allow the user to customize his or her graphical interface. Answer: Softphones Video-over-IP Applications and Interfaces 1. Mention Cisco’s estimate on future Internet video traffic. 2. Point out what must take place in order for the Cisco prediction to materialize. 3. Introduce the three categories of video-over-IP: a. Streaming video, IPTV, and videoconferencing Teaching Tip Students may see the Cisco press release announcing the prediction at http://newsroom.cisco.com/dlls/2008/prod_061608b.html Streaming Video 1. Remind students that streaming video is a service in which audiovisual signals are compressed and delivered over the Internet in a continuous stream. 2. Explain why streaming video is the simplest video-over-IP application. 3. Define and describe video-on-demand. 4. Define and describe streaming video. 5. Note the drawbacks of streaming video. 6. Use Figure 12-9 to illustrate video-on-demand and live streaming video services. 7. Explain why point-to-multipoint streaming video does not necessarily mean multicast transmission. 8. Mention that streaming video services may be classified according to the type of network they use. a. Describe a private service. b. Describe a public service. IPTV (IP Television) 1. Explain why local telephone companies are investing significant sums into the hardware and software that make IPTV possible. 2. Use Figure 12-10 to illustrate a telecommunications carrier’s IPTV network. 3. Describe elements coming together to deliver digital video to consumers. 4. Explain why multicasting makes sense for delivering IPTV. 5. Remind students that multicasting is managed by IGMP (Internet Group Management Protocol). 6. Point out that IGMP underlies all IPTV implementations at the Network layer of the OSI mode. 7. Describe how a compressed, digital video signal travels over the telecommunication’s network just as a data signal would. 8. Use Figure 12-11 to illustrate an IPTV set top box. 9. Describe a significant advantage of delivering video services over a telecommunications carrier’s or cable company’s network. Videoconferencing 1. Describe two characteristic of videoconferencing: a. Connections are full-duplex. b. Participants may send and receive audiovisual signals. 2. Describe the various uses for videoconferencing. 3. Describe the hardware and software requirements for videoconferences. 4. Use Figure 12-12 to illustrate a video phone. 5. Define a video bridge and describe its purpose. Teaching Tip Students may learn about The Cisco TelePresence Recording Server Solutions, including video recordings explaining its use at http://www.cisco.com/en/US/products/ps10341/index.html Signaling Protocols 1. Define signaling as referenced in VoIP and video-over-IP transmissions. 2. Describe some functions performed by signaling protocols. 3. Describe the type of signaling protocols used in the early days of VoIP. 4. Introduce the type of signaling protocols used today. H.323 1. Introduce the H.323 protocol and describe its function. 2. Describe five key elements identified by H.323. 3. Use Figure 12-13 to illustrate an H.323 zone comprising four terminals, one gateway, and one MCU. 4. Describe the H.225 signaling protocol. 5. Describe the H.245 signaling protocol. 6. Mention that the H.323 standard also specifies interoperability with certain protocols at the Presentation layer. 7. Describe the version history of H.323. 8. Introduce SIP. SIP (Session Initiation Protocol) 1. Describe SIP’s capabilities. 2. Note that SIP’s functions are more limited than those performed by the protocols in the H.323 group. 3. Describe components of a SIP network. 4. Use Figure 12-14 to illustrate how the elements of a SIP system may be arranged on a network. 5. Explain why many VoIP vendors prefer SIP. 6. Introduce the MGCP and MEGACO protocols. Teaching Tip Explain that Asterisk is a popular SIP-based open-source IP-PBX package. Provide a class demonstration by navigating to the Virtual SIP Trade Show at http://www.sipcenter.com/sip.nsf/html/IP+PBX, where Asterisk and other SIP-based products may be reviewed. Note the learning resources that are available. MGCP (Media Gateway Control Protocol) and MEGACO (H.248) 1. Emphasize that gateways are integral to converged networks. 2. Define the term “payload”. 3. Explain why separate physical paths are desired to expedite information handling. 4. Define and explain a MGC (media gateway controller). a. Note where they are most advantageous. 5. Introduce the MGC gateway communicate protocols. 6. Describe the MGCP (Media Gateway Control Protocol). 7. Present Figure 12-15 to illustrate the use of an MGC (media gateway controller). 8. Describe MEGACO. Transport Protocols 1. Note that MEGACO and MGC protocols communicate information about voice and video session information. 2. Point out that different protocols are needed to deliver voice or video payloads at the Transport OSI model layer. 3. Review how UDP and TCP operate in the transport layer. 4. Explain that UDP packet loss is tolerable if additional protocols to overcome UDP the shortcomings are available. RTP (Real-time Transport Protocol) 1. Define and explain the RTP (Real-time Transport Protocol) that helps voice and video networks overcome UDP’s shortcomings. RTCP (Real-time Transport Control Protocol) 2. Define and explain the RTCP (Real-time Transport Control Protocol) that helps voice and video networks overcome UDP’s shortcomings. 3. Note that the value of RTCP lies in what clients and their applications do with the information that RTCP supplies. 4. Mention that RTCP is not mandatory on networks that use RTP. 5. Explain why some network administrators prefer not to use it. 6. Point out that RTP and RTCP provide information about packet order, loss, and delay. 7. Emphasize that the RTP and RTCP protocols cannot do anything to correct transmission flaws. a. Explain that this task is handled by QoS protocols. QoS (Quality of Service) Assurance 1. Explain why it is more difficult to transmit VoIP and video over IP signals over a packet-switched network than it is to transmit data signals. 2. Define and explain QoS. 3. Note the advantage and disadvantages of QoS. 4. Emphasize that network engineers have developed several techniques to overcome the QoS challenges inherent in delivering voice and video over IP. RSVP (Resource Reservation Protocol) 1. Define and explain the RSVP (Resource Reservation Protocol). 2. Describe the path creation process between the sender and the receiver. a. Explain the PATH statement. b. Explain the RESV message. 3. Describe the two service types RSVP allows. a. Guaranteed service b. Controlled-load service 4. Explain why the resource reservation process must take place in both directions. 5. Describe RSVP messaging. 6. Describe the advantage of RSVP. 7. Describe the drawback of RSVP. 8. Point out that RSVP might be acceptable on small networks; however, it is less popular on large, heavily trafficked networks. DiffServ (Differentiated Service) 1. Define and explain the DiffServ (Differentiated Service). 2. Note how it differs from RSVP. 3. Explain why DiffServ is good for time-sensitive voice and video services. 4. Point out how DiffServ prioritizes traffic in IPv4 and IPv6. 5. Describe the two forwarding types: a. EF (Expedited Forwarding) b. AF (Assured Forwarding) MPLS (Multiprotocol Label Switching) 1. Define and explain MPLS (Multiprotocol Label Switching). Quick Quiz 2 1. True or False: Videoconferencing is a VoIP application. Answer: False 2. ____ is the protocol specified by the H.323 standard that handles call or videoconference signaling. a. H.225 b. H.245 c. H.248 d. H.252 Answer: A 3. ____________________, ensures that the type of information - whether voice or video - issued to an H.323 terminal is formatted in a way that the H.323 terminal can interpret. Answer: H.245 4. True or False: SIP does not attempt to perform and control as many functions as the H.323 protocols. Answer: True 5. Media gateways rely on an intermediate device known as a(n) ____________________ to exchange and translate signaling and control information with each other. Answer: MGC (media gateway controller), Media gateway controller, MGC 6. ____ is a simple technique that addresses QoS issues by prioritizing traffic. e. RTCP (Real-time Transport Control Protocol) f. RSVP (Resource Reservation Protocol) g. MPLS (multiprotocol label switching) h. DiffServ (Differentiated Service) Answer: D Class Discussion Topics 1. Skype, the popular Internet telephony software, is one type of softphone. Take an informal student poll to determine how many students use Skype. Are there other softphone products with which students have experience? Ask students to discuss their experiences with Skype and other softphones. What are the usability and technical benefits and drawbacks of these softphones? 2. Ask students to discuss the use of videoconferencing in their organizations. What are the real-world benefits and drawbacks of using it? If videoconferencing is not available, what arguments might convince the organization to implement it? Additional Projects 1. The discussion on Pages 569-570 presents several uses for videoconferencing. Have students select and research one use for delivering VoIP or video-over IP mentioned in the text and research the item. Ask each student to write a three to five page report summarizing his or her findings. The report should include the following sections: introduction; background and history; technical specifications; current real world implementation cases (two to three), barriers; and summary. 2. Have students select one client device type mentioned in this lesson for delivering VoIP or video-over IP and research the device type (IP telephone, softphone, videophone, etc.). Each student should write a report summarizing his or her findings. The report should include a comparison of three to five devices currently available for general use, including the manufacturer, the model, the seller, the cost, and a summary of the manufacturer specifications. Additional Resources 1. Microsoft Lync Server 2010 Conferencing http://technet.microsoft.com/en-us/library/gg398781.aspx 2. Microsoft Brings Software-Powered Videoconferencing to Desktops Everywhere http://www.microsoft.com/presspass/press/2008/mar08/03-17VoiceCon08PR.mspx 3. Cisco Product Solutions http://www.cisco.com/en/US/products/index.html 4. H.323 Forum http://www.h323forum.org 5. VOIP Wiki - a reference guide to all things VOIP http://www.voip-info.org Key Terms  AF (Assured Forwarding) In the DiffServ QoS technique, a forwarding specification that allows routers to assign data streams one of several prioritization levels. AF is specified in the DiffServ field in an IPv4 datagram.  analog telephone adapter See ATA.  Assured Forwarding See AF.  ATA (analog telephone adapter) An internal or externally attached adapter that converts analog telephone signals into packet-switched voice signals and vice versa.  Differentiated Service See DiffServ.  DiffServ (Differentiated Service) A technique for ensuring QoS by prioritizing traffic. DiffServ places information in the DiffServ field in an IPv4 datagram. In IPv6 datagrams, DiffServ uses a similar field known as the Traffic Class field. This information indicates to the network routers how the data stream should be forwarded.  digital PBX See IP-PBX.  EF (Expedited Forwarding) In the DiffServ QoS technique, a forwarding specification that assigns each data stream a minimum departure rate from a given node. This technique circumvents delays that slow normal data from reaching its destination on time and in sequence. EF information is inserted in the DiffServ field of an IPv4 datagram.  endpoint In SIP terminology, any client, server, or gateway communicating on the network.  Expedited Forwarding See EF.  H.225 A Session layer call signaling protocol defined as part of ITU’s H.323 multiservice network architecture. H.225 is responsible for call or videoconference setup between nodes on a VoIP or video-over-IP network, indicating node status, and requesting additional bandwidth and call termination.  H.245 A Session layer control protocol defined as part of ITU’s H.323 multiservice network architecture. H.245 is responsible for controlling a session between two nodes. For example, it ensures that the two nodes are communicating in the same format.  H.248 See MEGACO.  H.323 An ITU standard that describes an architecture and a suite of protocols for establishing and managing multimedia services sessions on a packet-switched network.  H.323 gatekeeper The nerve center for networks that adhere to H.323. Gatekeepers authorize and authenticate terminals and gateways, manage bandwidth, and oversee call routing, accounting, and billing. Gatekeepers are optional on H.323 networks.  H.323 gateway On a network following the H.323 standard, a gateway that provides translation between network devices running H.323 signaling protocols and devices running other types of signaling protocols (for example, SS7 on the PSTN).  H.323 terminal On a network following the H.323 standard, any node that provides audio, visual, or data information to another node.  H.323 zone A collection of H.323 terminals, gateways, and MCUs that are managed by a single H.323 gatekeeper.  hosted PBX A digital PBX service provided over the Internet.  Internet telephony The provision of telephone service over the Internet.  IP-PBX A private switch that accepts and interprets both analog and digital voice signals (although some IP-PBXs do not accept analog lines). It can connect with both traditional PSTN lines and data networks. An IP-PBX transmits and receives IP-based voice signals to and from other network connectivity devices, such as a router or gateway.  IP phone See IP telephone.  IP telephone A telephone used for VoIP on a TCP/IP-based network. IP telephones are designed to transmit and receive only digital signals.  IP telephony See Voice over IP.  IP television See IPTV.  IPTV (IP television) A service in which television signals from broadcast or cable networks travel over packet-switched networks.  MCU (multipoint control unit) A computer that provides support for multiple H.323 terminals (for example, several workstations participating in a videoconference) and manages communication between them. An MCU is also known as a video bridge.  media gateway A gateway capable of accepting connections from multiple devices (for example, IP telephones, traditional telephones, IP fax machines, traditional fax machines, and so on) and translating analog signals into packetized, digital signals, and vice versa.  Media Gateway Control Protocol See MGCP.  media gateway controller See MGC.  MEGACO A protocol used between media gateway controllers and media gateways. MEGACO is poised to replace MGCP on modern converged networks, as it supports a broader range of network technologies, including ATM. Also known as H.248.  MGC (media gateway controller) A computer that manages multiple media gateways and facilitates the exchange of call control information between these gateways.  MGCP (Media Gateway Control Protocol) A protocol used for communication between media gateway controllers and media gateways. MGCP is currently the most popular media gateway control protocol used on converged networks.  multipoint control unit See MCU.  PBX (private branch exchange) A telephone switch used to connect and manage an organization’s voice calls.  private branch exchange See PBX.  proxy server On a SIP network, a server that accepts requests for location information from user agents, then queries the nearest registrar server on behalf of those user agents. If the recipient user agent is in the SIP proxy server’s domain, then that server will also act as a go-between for calls established and terminated between the requesting user agent and the recipient user agent.  Real-time Transport Control Protocol See RTCP.  Real-time Transport Protocol See RTP.  redirect server On a SIP network, a server that accepts and responds to requests from user agents and SIP proxy servers for location information on recipients that belong to external domains.  registrar server On a SIP network, a server that maintains a database containing information about the locations (network addresses) of each user agent in its domain. When a user agent joins a SIP network, it transmits its location information to the SIP registrar server.  Resource Reservation Protocol See RSVP.  RSVP (Resource Reservation Protocol) As specified in RFC 2205, a QoS technique that attempts to reserve a specific amount of network resources for a transmission before the transmission occurs.  RTCP (Real-time Transport Control Protocol) A companion protocol to RTP, RTCP provides feedback on the quality of a call or videoconference to its participants.  RTP (Real-time Transport Protocol) An Application layer protocol used with voice and video transmission. RTP operates on top of UDP and provides information about packet sequence to help receiving nodes detect delay and packet loss. It also assigns packets a time stamp that corresponds to when the data in the packet were sampled from the voice or video stream. This time stamp helps the receiving node synchronize incoming data.  RTP Control Protocol See RTCP.  Session Initiation Protocol See SIP.  set-top box In the context of IPTV, a device that decodes digital video signals and issues them to the television. Set-top boxes also communicate with content servers to manage video delivery.  signaling The exchange of information between the components of a network or system for the purposes of establishing, monitoring, or releasing connections as well as controlling system operations.  Signaling System 7 See SS7.  SIP (Session Initiation Protocol) A protocol suite codified by the IETF as a set of Session layer signaling and control protocols for multiservice, packet-based networks. With few exceptions, SIP performs much the same functions as the H.323 signaling protocols perform.  softphone A computer configured to act like an IP telephone. Softphones present the caller with a graphical representation of a telephone dial pad and can connect to a network via any wired or wireless method.  Softswitch See MGC.  SS7 (Signaling System 7) A set of standards established by the ITU for handling call signaling on the PSTN (Public Switched Telephone Network).  streaming video A service in which video signals are compressed and delivered over the Internet in a continuous stream so that a user can watch and listen even before all the data have been transmitted.  toll bypass A cost-savings benefit that results from organizations completing long-distance telephone calls over their packet-switched networks, thus bypassing tolls charged by common carriers on comparable PSTN calls.  unified messaging The centralized management of multiple types of network-based communications, such as voice, video, fax, and messaging services.  user agent In SIP terminology, a user agent client or user agent server.  user agent client In SIP terminology, end-user devices such as workstations, tablet computers, smartphones, or IP telephones. A user agent client initiates a SIP connection.  user agent server In SIP terminology, a server that responds to user agent clients’ requests for session initiation and termination.  video bridge See MCU.  video-on-demand A service in which a video stored as an encoded file is delivered to a viewer upon his request.  video over IP Any type of video service, including IPTV, videoconferencing, and streaming video, that delivers video signals over packet-switched networks using the TCP/IP protocol suite.  video phone A type of phone that includes a screen and can decode compressed video and interpret transport and signaling protocols necessary for conducting videoconference sessions.  videoconferencing The real-time reception and transmission of images and audio among two or more locations.  virtual PBX See hosted PBX.  Voice over IP See VoIP.  VoIP (Voice over IP) The provision of telephone service over a packet-switched network running the TCP/IP protocol suite.  Webcast A streaming video, either on demand or live, that is delivered via the Web. Chapter 13 Troubleshooting Network Problems At a Glance Instructor’s Manual Table of Contents • Overview • Objectives • Teaching Tips • Quick Quizzes • Class Discussion Topics • Additional Projects • Additional Resources • Key Terms Lecture Notes Overview Many things can go wrong on a network. In fact, a network professional probably spends more time fixing network problems than designing or upgrading a network. Some breakdowns (such as an overtaxed processor) come with plenty of warning, but others (such as a hard disk controller failure) can strike instantly. The best defense against problems is prevention. Of course, even the most well monitored network will sometimes experience unexpected problems. In this chapter, the student will learn how to diagnose and solve network problems in a logical, step-by-step fashion, using a variety of tools. Chapter Objectives After reading this chapter and completing the exercises, the student will be able to: • Describe the steps involved in an effective troubleshooting methodology • Follow a systematic troubleshooting process to identify and resolve networking problems • Document symptoms, solutions, and results when troubleshooting network problems • Use a variety of software and hardware tools to diagnose problems Teaching Tips Troubleshooting Methodology 1. Introduce basic trouble shooting methodology. 2. Mention that these steps follow the recommendations specified in CompTIA’s Network+ exam objectives. Identify the Problem and its Symptoms 1. Describe the first step in troubleshooting. 2. Explain the eight questions necessary to obtain more information about symptoms of a network problem that are not immediately obvious. 3. Explain one danger to avoid in troubleshooting technical problems. 4. Remind students to take the time to pay attention to the users, system and network behaviors, and any error messages. 5. Describe the second step in troubleshooting. 6. Review the areas to consider when determining how many users or network segments are affected. 7. Review the questions to ask when determining the time frame during which the problem occurred. 8. Describe the benefit of narrowing down the area affected by a problem. 9. Explain the importance of taking the time to troubleshoot correctly. 10. Describe the benefit of discovering the time or frequency with which a problem occurs. 11. Describe the benefits of identifying the affected area of a problem. 12. Use Figures 13-1 and 13-2 to illustrate the direction that can be gained from narrowing both the demographic (or geographic) and the chronological scopes of a problem 13. Describe the third step in troubleshooting. 14. Emphasize that students should be aware of any recent changes to the network. 15. Review questions that could help pinpoint a problem resulting from a network change. 16. Explain what can be done if an administrator suspects that a network change has generated a problem. 17. Explain why the IT Department should keep complete network change records. Establish a Theory of Probable Cause 1. Describe the fourth step in troubleshooting. a. Note that a troubleshooter should be close to determining the problem’s cause at this point. 2. Explain why there is a need to verify user competency. a. Describe how to verify user competency. b. Describe the possible results from verifying user competency. 3. Describe the benefit of re-creating the symptoms of a problem. a. Explain how to go about re-creating the problem. b. Review the questions to ask to determine whether a problem’s symptoms are truly reproducible and, if so, to what extent. 4. Explain why there is a need to verify Physical layer connectivity. a. Explain why an administrator should be thoroughly familiar with the symptoms of network problems occurring at the Physical layer of the OSI model. 5. Describe symptoms of Physical layer problems. a. Discuss the types of problems that physical connectivity issues do not typically affect. b. Emphasize that some software errors may point to a physical connectivity problem. 6. Explain how an administrator should go about diagnosing Physical layer problems: a. Ask questions. b. Verify connection between devices. c. Verify the soundness of the hardware used in those connections. 7. Describe the importance of being able to swap equipment. a. Describe how to swap or exchange components. b. Note a better overall solution is to build in redundancy. 8. Use the flowchart in Figure 13-3 to illustrate how logically assessing Physical layer elements can help an administrator solve a network problem. 9. Explain why there is a need to verify logical connectivity. a. Review the questions that may help identify a problem with logical connectivity. b. Explain why logical connectivity problems often prove more difficult to isolate and resolve than physical connectivity problems. c. Review some possible software-based causes for a failure to connect to the network. Test the Theory to Determine Cause 1. Describe the fifth step in troubleshooting. 2. Explain the various roles within a help desk area. 3. Note that all troubleshooters should follow procedures for when and how to escalate problems. Establish a Plan of Action to Resolve the Problem 1. Introduce the sixth step in troubleshooting. 2. Remind students that they must consider how a solution might affect users and network functionality. 3. Discuss one of the most important aspects to consider: the breadth, or scope, of the change. 4. Discuss another factor that must be considered: the trade-off a solution might impose. 5. Explain how security implications of a solution may inadvertently result in the addition or removal of network access or resource privileges for a user or group of users. 6. Explain why considering scalability is important when deciding on long term or temporary solutions. 7. Explain why the costs of solutions must be considered. 8. Discuss the various support outlets for obtaining vendor product troubleshooting information. Teaching Tip Demonstrate the availability of free vendor support by navigating to Microsoft’s TechNet area at http://technet.microsoft.com Implement the Solution or Escalate as Necessary 1. Introduce the seventh step in troubleshooting. a. Emphasize that the solution is implemented only after the effects have been researched. 2. Review implementation considerations. a. Explain why implementing a solution requires foresight and patience. b. Explain why students should follow a methodical and logical approach. c. Review common steps that steps will help a student implement a safe and reliable solution. 3. Explain when it is best to roll out changes in stages. 4. Note that after implementing a solution, the administrator must test its result and verify that it solved the problem properly. a. Describe the dependencies that might affect testing. Verify Full System Functionality 1. Introduce the eighth step in troubleshooting. 2. Describe the steps that should be taken after testing the solution implementation. Document Findings, Actions, and Outcomes 1. Describe the ninth step in troubleshooting. 2. Discuss ways to document the solution and process. a. Explain the purpose of and components in a call tracking system. 3. Review the fields that should be included in a typical problem record if no call tracking system is available. 4. Define and describe a supported services list document. 5. Explain why it is important to follow-up with the user. Teaching Tip Demonstrate the availability of a call tracking systems by performing a Google search with the keywords “network call tracking software”. Review and discuss the results list with the class. 6. Discuss methods for notifying others of changes. a. Emphasize the importance of recording a problem’s resolution in the call tracking system, and notifying others of the solution. b. Describe the two purposes this communication serves. 7. Discuss the types of changes that network personnel should record in a change management system. 8. Point out that it is generally not necessary to record minor modifications. Teaching Tip Microsoft System Center Essentials 2010 is a commercial product providing a unified management solution that enables IT professionals in midsize organizations to proactively manage their IT environment with increased efficiency. Navigate to the product Web site at http://www.microsoft.com/systemcenter/essentials to demonstrate the products capabilities. Quick Quiz 1 1. True or False: Experience in a network environment may prompt a network professional to follow the troubleshooting steps in a different order or to skip certain steps entirely. Answer: True 2. One danger in troubleshooting technical problems is jumping to conclusions about the ____________________. Answer: symptoms 3. To find the probable cause, you might need to ____. a. Identify the symptoms and problems b. Verify user competency c. Determine what has changed d. Determine whether escalation is necessary Answer: B 4. Physical connectivity problems often prove more difficult to isolate and resolve than logical connectivity problems because they can be more complex. Answer: False 5. True or False: It is best to roll out changes in stages for large systems. Answer: True Troubleshooting Tools 1. Introduce the subject of troubleshooting tools. 2. Remind students of the ping command and its use. 3. Note that most efficient troubleshooting approach is to use a tool specifically designed to analyze and isolate network problems. 4. Point out that the tool selected depends on the specific problem and the characteristics of the network. Tone Generator and Tone Locator 1. Describe the ideal and realistic characteristics of telecommunications wiring. 2. Define and explain the use of a tone generator. 3. Define and explain the use of a tone locator. 4. Point out that when a tone generator and a tone locator are sold together, they are called a probe kit. 5. Use Figure 13-4 to illustrate the use of a tone generator and a tone locator. a. Note that testing requires trial and error technique. b. Point out this combination of devices is also known as a fox and hound, because the locator (the hound) chases the generator (the fox). 6. Describe the use of tone generators and tone locators. 7. Emphasize that tone generators and tone locators cannot be used to determine any characteristics about a cable, such as whether it is defective or whether its length exceeds IEEE standards for a certain type of network. Teaching Tip Emphasize that a tone generator should never be used on a wire that is connected to a device’s port or network adapter. Because a tone generator transmits electricity over the wire, it could damage the device or network adapter. Multimeter 1. Describe and explain how a multimeter works. 2. Describe a voltmeter. 3. Describe and explain resistance. 4. Describe and explain impedance. 5. Use Figurer 13-5 to illustrate a multimeter. Cable Continuity Testers 1. Define and describe cable checkers. 2. Explain how copper-base cable checkers work. 3. Explain how fiber-optic continuity checkers work. 4. Emphasize the importance of testing all network cables whether homemade or purchased for correct reading. 5. Describe the convenience factors cable continuity checkers offer. 6. Use Figurer 13-6 to illustrate two cable continuity checkers. Teaching Tip Popular manufacturers of cable testing devices include Belkin, Fluke, Microtest, and Paladin. Navigate to the Fluke Web site at http://www.flukenetworks.com/enterprise-network#Troubleshooting_Tools and review their products and articles on a variety of topics. Cable Performance Testers 1. Define and describe cable performance testers. 2. Explain the differences between continuity testers and performance testers. 3. Explain TDR (time domain reflectometer). 4. Describe fiber-optic continuity testers. 5. Explain the functionality of OTDRs (optical time domain reflectometers). 6. Note the expense of cable performance testers. 7. Use Figurer 13-7 to illustrate a cable performance tester. Voltage Event Recorders 1. Define and describe a voltage event. 2. Describe a voltage event recorder. 3. Use Figure 13-8 to illustrate a voltage event recorder. Butt Set 1. Define and describe a butt set. 2. Explain why this device is often referred to as a lineman’s handset or telephone test set. 3. Describe how a butt set can be used for troubleshooting. 4. Use Figure 13-9 to illustrate a butt set. Network Monitors 1. Define and explain network monitors. 2. Discuss the various places from which a network monitor may be obtained. 3. Point out that all network monitors tend to use similar graphical interfaces. 4. Mention that to take advantage of network monitoring and analyzing tools, the network adapter installed in the machine running the software must support promiscuous mode. 5. Describe the functions all network monitoring tools can perform. 6. Describe some additional functions that network monitoring tools can perform. 7. Explain how capturing data help you solve a problem. 8. Review some commonly used terms for abnormal data patterns and packets, along with their characteristics. Teaching Tip Students may read more on analyzing network data with Network Monitor at http://technet.microsoft.com/en-us/library/cc723623.aspx Protocol Analyzers 1. Define and describe protocol analyzers. 2. Discuss the variety of protocol analyzer tools available. 3. Discuss the features of protocol analyzers as compared to network monitors. 4. Explain the history of the term sniffer. 5. Use Figure 13-10 to illustrate the distribution of traffic captured by a protocol analyzer. 6. Describe the versatility protocol analyzers offer. 7. Explain what information needs to be gathered before using the protocol analyzer. Wireless Network Testers 1. Define and describe the software and hardware wireless networking tools available. 2. Explain the three advantages of using a vendor supplied tool. 3. Use Figure 13-11 to illustrate a wireless network testing tool. Teaching Tip Students may read more information on troubleshooting tools at http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1902.html Quick Quiz 2 1. A ____ is useful for quickly and easily verifying that a node’s NIC is transmitting and receiving signals properly. a. crossover cable b. tone generator c. multimeter d. continuity tester Answer: A 2. True or False: The difference between continuity testers and performance testers lies in their sophistication and price. Answer: True 3. A(n) ____________________ collects data about power quality. Answer: voltage event recorder 4. True or False: Some NOSs come with network monitoring tools. Answer: True 5. A(n) ____________________ is a tool that can assess the quality of the wireless signal. Answer: spectrum analyzer Class Discussion Topics 1. As a class, discuss the importance of documenting network problems and solutions. What can be done if a lack of time interferes with the documentation process? 2. As a class, discuss the similarities and differences between a network monitor and a protocol analyzer. Is there overlap in functionality? Are there distinguishing characteristics? Additional Projects 1. Hundreds of network monitoring tools exist. You can purchase or download free network monitoring tools developed by software companies. Students should go to the Web and research three network-monitoring tools, and provide a report of their findings. The report should include a comparison of the products. Additional Resources 1. Project Management Institute http://www.pmi.org 2. Microsoft TechNet http://technet.microsoft.com 3. Cisco support page http://www.cisco.com/en/US/support 4. Windows Networking home page http://www.windowsnetworking.com 5. Wireshark http://www.wireshark.org 6. Netscout http://www.netscout.com/Pages/default.aspx 7. Black box online store http://www.blackbox.com/store/storefront.aspx Key Terms  baseline - A record of how a network operates under normal conditions (including its performance, collision rate, utilization rate, and so on). Baselines are used for comparison when conditions change.  butt set - A tool for accessing and testing a telephone company’s local loop. The butt set, also known as a telephone test set or lineman’s handset, is essentially a telephone handset with attached wires that can be connected to local loop terminations at a demarc or switching facility.  cable checker - See continuity tester.  cable performance tester - A troubleshooting tool that tests cables for continuity, but can also measure cross talk, attenuation, and impedance; identify the location of faults; and store or print cable testing results.  cable tester - A device that tests cables for one or more of the following conditions: continuity, segment length, distance to a fault, attenuation along a cable, near-end cross talk, and termination resistance and impedance. Cable testers may also issue pass/fail ratings for wiring standards or store and print cable testing results.  call tracking system - A software program used to document technical problems and how they were resolved (also known as help desk software).  change management system - A process or program that provides support personnel with a centralized means of documenting changes made to the network.  continuity tester - An instrument that tests whether voltage (or light, in the case of fiber-optic cable) issued at one end of a cable can be detected at the opposite end of the cable. A continuity tester can indicate whether the cable will successfully transmit a signal.  escalate - In network troubleshooting, to refer a problem to someone with deeper knowledge about the subject. For example, a first-level support person might escalate a router configuration issue to a second- or third-level support person.  first-level support - In network troubleshooting, the person or group who initially fields requests for help from users.  ghost - A frame that is not actually a data frame, but rather an aberration caused by a device misinterpreting stray voltage on the wire. Unlike true data frames, ghosts have no starting delimiter.  giant - A packet that exceeds the medium’s maximum packet size. For example, any Ethernet packet that is larger than 1518 bytes is considered a giant.  help desk analyst - A person who is proficient in basic (but not usually advanced) workstation and network troubleshooting. Help desk analysts are part of first-level support.  help desk coordinator - A person who ensures that help desk analysts are divided into the correct teams, schedules shifts at the help desk, and maintains the infrastructure to enable analysts to better perform their jobs. They might also serve as third-level support personnel, taking responsibility for troubleshooting a problem when the second-level support analyst is unable to solve it.  jabber - A device that handles electrical signals improperly, usually affecting the rest of the network. A network analyzer will detect a jabber as a device that is always retransmitting, effectively bringing the network to a halt. A jabber usually results from a bad NIC. Occasionally, it can be caused by outside electrical interference.  late collision - A collision that takes place outside the normal window in which collisions are detected and redressed. Late collisions are usually caused by a defective station (such as a card, or transceiver) that is transmitting without first verifying line status or by failure to observe the configuration guidelines for cable length, which results in collisions being recognized too late.  lineman’s handset - See butt set.  local collision - A collision that occurs when two or more stations are transmitting simultaneously. Excessively high collision rates within the network can usually be traced to cable or routing problems.  multimeter - A simple instrument that can measure multiple characteristics of an electric circuit, including its resistance and voltage.  negative frame sequence check - The result of the CRC (cyclic redundancy check) generated by the originating node not matching the checksum calculated from the data received. It usually indicates noise or transmission problems on the LAN interface or cabling. A high number of (nonmatching) CRCs usually results from excessive collisions or a station transmitting bad data.  network analyzer - See protocol analyzer.  network monitor - A software-based tool that monitors traffic on the network from a server or workstation attached to the network. Network monitors typically can interpret up to Layer 3 of the OSI model.  Network Monitor - A network monitoring program from Microsoft that comes with Windows operating systems.  ohmmeter - A device used to measure resistance in an electrical circuit.  optical time domain reflectometer - See OTDR.  OTDR (optical time domain reflectometer) - A performance testing device for use with fiber-optic networks. An OTDR works by issuing a light-based signal on a fiber-optic cable and measuring the way in which the signal bounces back (or reflects) to the OTDR. By measuring the length of time it takes the signal to return, an OTDR can determine the location of a fault.  packet sniffer - See protocol analyzer.  probe - See tone locator.  promiscuous mode - The feature of a network adapter that allows it to pick up all frames that pass over the network - not just those destined for the node served by the card.  protocol analyzer - A software package or hardware-based tool that can capture and analyze data on a network. Protocol analyzers are more sophisticated than network monitoring tools, as they can typically interpret data up to Layer 7 of the OSI model.  second-level support - In network troubleshooting, a person or group with deeper knowledge about a subject and to whom first-level support personnel escalate problems.  sniffer - See protocol analyzer.  spectrum analyzer - A tool that assesses the characteristics (for example, frequency, amplitude, and the effects of interference) of wireless signals.  supported services list - A document that lists every service and software package supported within an organization, plus the names of first- and second-level support contacts for those services or software packages.  TDR (time domain reflectometer) - A high-end instrument for testing the qualities of a cable. It works by issuing a signal on a cable and measuring the way in which the signal bounces back (or reflects) to the TDR. Many performance testers rely on TDRs.  telephone test set - See butt set.  third-level support - In network troubleshooting, a person or group with deep knowledge about specific networking topics to whom second-level support personnel escalate challenging problems.  time domain reflectometer - See TDR.  tone generator - A small electronic device that issues a signal on a wire pair. When used in conjunction with a tone locator, it can help locate the termination of a wire pair.  tone locator - A small electronic device that emits a tone when it detects electrical activity on a wire pair. When used in conjunction with a tone generator, it can help locate the termination of a wire pair.  toner - See tone generator.  voltage event - Any condition in which voltage exceeds or drops below predefined levels.  voltage event recorder - A device that, when plugged into the same outlet that will be used by a network node, gathers data about the power that outlet will provide the node.  voltmeter - A device used to measure voltage (or electrical pressure) on an electrical circuit. Instructor Manual for Network+ Guide to Networks Tamara Dean 9781133608196, 9781133608257, 9781337569330