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. 410 Appendix A: Answers to Quiz Questions6 Briefly describe the advantages of Netflow switching.Also specify whether thereshould be any precautions with respect to enabling Netflow switching.Netflow switching caches security information and accounting information aswell as routing information for each flow.Hence, once a network flow is identifiedand the first packet (of the flow) is processed, for the following packets the accesslist checks are bypassed and packet switching and statistics captures areperformed in tandem.Netflow also allows for exporting captured data tomanagement utilities.Netflow switching, especially with the export option, canbe quite resource consuming, so caution must be exercised when enabling thisfeature in production network routers.7 Provide at least three examples of operations or packet types that are processswitched.Data-link layer broadcastsPackets subjected to DebugPackets delivering error log messages to syslogSNMP packetsProtocol translationsTunnelingCustom and priority queuingLink compressionKeepalives8 Before you activate Debug, what are some of its characteristics that you shouldconsider?Debug is treated as a very high priority task, it can consume a significant amountof resources, and the router is forced to process-switch the packets beingdebugged.9 Before you enable debugging on a router, you are encouraged to check the router sCPU utilization.What is the command that allows you to do that? If the utilization isabove 50%, are you encouraged to debug packets or to debug events?Before starting to use the debug command, see the CPU utilization of your routerusing the show processes cpu exec command.If your router s CPU utilization isconsistently at 50% or more, you are advised to debug events instead of packets. Chapter 4 41110 What is the default setting (for example, enabled/disabled, default destination) formessage logging?Message logging is enabled by default and it is directed to the console line andthe internal buffer.11 What information does the output of the show logging Cisco IOS exec commanddisplay?It displays the state of syslog error and event logging, which type of logging(destination) is enabled, and the messages that are currently stored in theinternal buffer.12 The outputs of the show memory and the show processes [cpu] commands will mostlikely be asked for in which situation (loss of functionality, crash, or performancedegradation)?Performance degradation.13 If the output of show buffer command displays a large number of misses, increasingthe value of which one of the buffer management parameters (Permanent, Min-Free,Max-Free, Initial) will most likely remedy the situation?Permanent and Min-Free.14 The show processes command s output provides two numbers separated by a slash(for example, 4%/4%) for the CPU utilization over the last five seconds.How arethose numbers interpreted?The first number is the total CPU utilization, and the second one is the utilizationdue to interrupt routines (in the last five seconds).15 Which command causes the router to attempt to produce a core dump when it crashes?The exception dump ip-address global configuration command (ip-address is theaddress of your TFTP, FTP, or RCP server) causes the router to attempt toproduce a core dump when it crashes.Q&A1 Briefly explain why Cisco IOS troubleshooting commands and tools need properhandling.Despite their importance in terms of the valuable information they provide, thesetools inevitably utilize some processing cycles and memory of the router.Furthermore, they may disable or at least have a negative effect on some of therouter s internal (optimized) operations such as fast switching. 412 Appendix A: Answers to Quiz Questions2 What does proper handling of troubleshooting tools entail?Proper usage of troubleshooting tools means that you should be selective aboutwhich one you use and use it with appropriate focus to gather the desiredinformation.You must stop using these tools immediately after you attain yourobjective.You should also limit the period of time during which these tools areused.3 Define switching and specify whether it is considered a complex task.Switching is commonly defined as the process that takes charge of moving dataunits (in other words, frames or packets) through the anatomy of aninternetworking device.The mere task of moving a data unit (a packet, in thecontext of routers) from one internal component to another is one of the simplestand least resource-consuming tasks.4 Define routing and compare its complexity to switching.Routing can be simply defined as the operation that attempts to select an outputinterface and perhaps a next hop for a packet, usually based on the packet sdestination address.Routing is considered more complex and resourceconsuming than switching.5 List the sources of information used by a routing process for building its routing table. The network segments that the router is actively connected to The usable static routes available in the router configuration The dynamic routing entries that the routing protocols offer The routing policies or restrictions that are imposed The usable default routes available6 When a packet is process-switched, what major tasks are performed?Both routing and switching.7 Provide a short and generic explanation for route caching (or fast switching) and thepurpose behind it.During a time interval, the packets that are arriving into a router can be dividedinto a number of groups, each of which comprises a bunch of packets with acommon destination.Because a router usually forwards those packets with thesame destination in a similar way (i.e., out from the same interface), the result ofthe routing decision made based on processing of the first packet of a particulargroup (all those with the same destination) can be reused on the followingpackets (with the same destination address).This is called route caching
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