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.message and receive a normal LMI status?How often does the router receive the FULL LMI message?______________________________________________________________________________________________________________________________________________________________________________________________________38 Which Frame Relay troubleshooting debug command displays the LMI messagesthat are exchanged between your router and the Frame Relay switch?______________________________________________________________________________________________________________________________________________________________________________________________________39 If you enter the debug frame-relay lmi command and you do not see a proper flow/exchange of LMI messages between your router and the Frame Relay switch (or yousee no LMI at all), assuming that the interface is up, what could be wrong?______________________________________________________________________________________________________________________________________________________________________________________________________40 Which command displays debugging information about the packets that are beingreceived on Frame Relay interface(s)?______________________________________________________________________________________________________________________________________________________________________________________________________41 Which Cisco router IOS command displays debugging information about FrameRelay ARP activities?______________________________________________________________________________________________________________________________________________________________________________________________________ Q&A 34142 Which Frame Relay debug command displays the packets that have been sent (out)on Frame Relay interface(s)?_________________________________________________________________________________________________________________________________________________________________________________________________________You need to refer to the following figure to answer the remaining questions (on FrameRelay troubleshooting commands):DAFrame RelaynetworkX BC43 Provide the two most appropriate show commands to test the area marked by theletter A._________________________________________________________________________________________________________________________________________________________________________________________________________ 342 Chapter 10: Diagnosing and Correcting Frame Relay Problems44 Provide the two most appropriate debug commands to test the area marked by theletter B.______________________________________________________________________________________________________________________________________________________________________________________________________45 Provide the two most appropriate show commands to test the area marked by theletter C.______________________________________________________________________________________________________________________________________________________________________________________________________46 Provide the two most appropriate debug commands to test the area marked by theletter D.______________________________________________________________________________________________________________________________________________________________________________________________________ This chapter covers the following topics that you will need to master to pass the CCNPSupport exam:Objective Description1 ISDN components and reference points.2 ISDN BRI channels.3 ISDN BRI Layer 1 specifications and activation.4 ISDN BRI Layer 1 troubleshooting commands.5 ISDN Layer 2 initialization.6 Troubleshooting ISDN Layer 2.7 Troubleshooting DDR for triggering an ISDN call.8 ISDN Layer 3 specifications.9 ISDN switch types.10 ISDN SPID numbers.11 ISDN call screening.12 PPP over B channels.13 PPP negotiation, authentication, and multilink. C H A P T E R11Diagnosing and Correcting ISDNBRI ProblemsISDN is a circuit-switched wide-area service that provides end-to-end digital connectionbetween remote devices.Similarly to other WAN services, the ISDN service is used toprovide connectivity between remote offices through a service provider s network.Thephysical devices and media that provide this complete connectivity fall into one of threecategories: customer premises equipment (CPE), local access loops, and service providernetworks.The communication between these devices is a formalized and standardizedprocess.Our focus will be on customer premises equipment and the local access loop.It isimportant to know the different types of equipment that may be involved, the ISDNreference points, and, most importantly, how these devices can be connected and configuredto get all three layers of ISDN up and running.Once all layers of ISDN layers arefunctional, an end-to-end circuit is built on demand.An end-to-end ISDN circuit is madeof at least one B channel, which by nature is a point-to-point physical link.Data-link andupper layer protocols can then be configured at both ends of the connection to transmit dataover the B channel(s).This chapter provides a detailed coverage of how initialization, working condition, andconfiguration of each component and functional layer of an ISDN connection can beexamined.The results of various misconfigurations are discussed to help you learn to moreeffectively troubleshoot ISDN connections.A comprehensive set of related IOS show anddebug commands are presented along with their sample output to help you fully appreciatethe purpose of each command. Do I Know This Already? QuizIf you wish to evaluate your knowledge of the contents of this chapter before you getstarted, answer the following questions.The answers are provided in Appendix A, Answers to Quiz Questions. If you are having difficulty providing correct answers, youshould thoroughly review the entire chapter [ Pobierz całość w formacie PDF ]