cisco ccna 3

Author: fi3ta

Post on 09-Jan-2016




0 download

Embed Size (px)




CCNA 3 All Modules - Revision Paul FlynnPage 11. VLSM stands for:Variable Length Subnet Masking2. The purpose VLSM was designed was to:Conserve IP addresses when using IPv4, maximizing the number ofuseable IP addresses available in a network.3. Dynamic routing protocols that support VLSM include:OSPFRIP v. 2EIGRPIS-IS4. VLSM is sometimes referred to as __________________________.Subnetting a subnet5. What is an autonomous system?its a network used in one enterprise6. What is meant by route aggregation?Its the same thing as route summarization; its a way to summarize morethan 1 route with one route entry in a routers routing table.7. How can you take advantage of route aggregation using VLSM?Make sure your VLSM routes are not distant from each other. This wayroutes can be aggregated into one route in the routing table.8. Is RIP v. 1 a classful or classless protocol? RIP v. 2? What does this mean?RIP v. 1 is classful; RIP v. 2 is classless. It means that RIP v. 1 must staywithin the normal IP class system (A, B, C); classless means RIP v. 2 canuse VLSM.CCNA 3 All Modules - Revision Paul FlynnPage 29. Because its a new protocol, can RIP v. 2 hop more than 16 times?No. It still has many of the same characteristics of RIP v. 1, including hopcount max of 16.10. What is the configuration command to start RIP v. 2 running?Router(config)#router ripRouter(config-router)#version 2Router (config-router)#network [attached network(s)]orRouter(config)#router rip ver 211. What show commands can you use to ensure that RIP v. 2 has started running?show ip routeshow ip protocols12. What is the command to flush (clear) the routing table to force an update?clear ip route *13. What will you see if you use the debug ip rip command?Youll see all the RIP updates as they are sent and received by the router.14. How do you turn off the debugging function?Add no to the same command you used to turn it on, or you can use theno debug all to turn off all debugging.15. What are the three (3) ways that routers learn about routes (networks)? Brieflyexplain each one.Static routing - additions to the routing table put in by the networkadministratorDynamic routing additions to the routing table are added automatically asrouters update themselves using protocolsDefault routes - default routes added to the routing table by the networkadministrator that indicates the path to take when there is no known routeto the destination16. What are the two commands that can be used to enter a default route?ip route [network no.] [subnet mask] [next hop IP address]ip default-network [network to use as default]CCNA 3 All Modules - Revision Paul FlynnPage 317. If you want to use the ip route command to specify a default network, how wouldyou enter it?ip route [next hop IP address]CCNA 3 All Modules - Revision Paul FlynnPage 4INTERNETWORKING IIIMODULE 1VLSM EXERCISE 1ObjectiveCreate an addressing scheme using variable-length subnet masking (VLSM).ScenarioYou are assigned the Class C address and must support the network shown in the diagram.Create an addressing scheme that meets the requirements shown in the diagram above.CCNA 3 All Modules - Revision Paul FlynnPage 5INTERNETWORKING IIIMODULE 1VLSM EXERCISE 2ObjectiveCreate an addressing scheme using VLSM.ScenarioYou are assigned the CIDR address /23 and must support the network shown in thediagram. Create an addressing scheme that meets the requirements shown in the diagram.CCNA 3 All Modules - Revision Paul FlynnPage 6CCNA 3.0 RIPv2Basic RIPv2 CommandsEnabling the RIPv2 processRouter(config)# router ripRouter(config-router)# version 1|2Enabling the RIP on an interfaceRouter(config-router)# network networkSummarization CommandsRIPv2 CommandsRouter(config-router)# no auto-summaryLike RIPv1, RIPv2 automatically summarizes as major network boundaries.This command turns off automatic summarization, useful for discontiguous networks.This command can only be used with RIPv2, and not with RIPv1.Extra: Interface CommandsRouter(config-if)# ip summary-address rip ip-address ip_network_maskPropagating a Default RouteMethod 1: Quad-Zero Static RouteRouter(config)# ip route exit-interface|ip-addressRouter(config)# router ripRouter(config-router)# default-information originateRequired starting with IOS 12.1Method 2: ip default-network commandRouter(config)# router ripRouter(config-router)# ip default-network network-addressRouter(config)# ip route network-addressCCNA 3 All Modules - Revision Paul FlynnPage 71. What are the two main ways of classifying dynamic IGP routing protocols?Distance-vectorLink-state2. Which ones are also known as shortest path first protocols? Why?Link-state, because thats exactly what they do: they look for the shortestpath to the destination (regardless of whether or not this is the BEST path).3. Fill in the following table:Type Protocol(s) Advantages DisadvantagesDistance-Vector RIP v. 1RIP v. 2IGRPEasy to configureUpdates regularlyTakes up significantbandwidthSlow to convergeSubject to routing loopsRIP only has 1 metricOnly RIP v. 2 can useVLSMLink-State OSPF,IS-ISOnly sends outupdates as neededDoesnt use muchbandwidth to maintaintablesFast to convergeNot subject to routingloopsKnows completetopology of network soknows all routesUses cost metricsinstead of distancemetricsCan use VLSM andCIDRDifficult to configurecorrectlyRequires more memoryand more powerfulCPUs in routersTakes a lot of bandwidthwhen first started4. What are hello packets used for?Link state protocols use them to make sure a link is still active. Theyrevery small packets.CCNA 3 All Modules - Revision Paul FlynnPage 85. What are the five things that link state protocols use to maintain their tables:Link-state advertisements (LSAs)A topological databaseThe shortest path first (SPF) algorithmThe resulting SPF treeA routing table of paths and ports to each network to determine the bestpaths for packets6. What is meant by a link when talking about link state protocols?A link is an interface on a router.7. How does a link state protocol build its topological database? What kind ofinformation is in it?Its a database of the entire topology of the network and includes each link andhow to reach it. Its built by using the LSAs that have been received by the router.8. What are the three types of networks recognized by OSPF?Broadcast multi-access, such as EthernetNonbroadcast multi-access (NBMA), such as frame relayPoint-to-point networks9. What is the DR and the BDR in an OSPF network? What do they do?DR Designated Router acts as the brains of the network. This routermakes sure that all the LSAs are sent to all the other routers in theArea.BDR Backup Designated Router acts as the second in command of thenetwork. If the DR goes down, the BDR takes over as DR. However,until the DR goes down, the BDR does not send out LSAs to any otherrouters in the Area.10. What is the multicast address used by the DR to send out LSAs to all otherOSPF routers? For LSAs just to other designated (and backup) routers? 3 All Modules - Revision Paul FlynnPage 911. What is a hello packet used for and what is the multicast address used for it?Why this address?A hello packet is the way OSPF routers make sure that a link is still active. is the address used so that all links are checked, not just DRs andBDRs.12. What is the default hello interval?10 seconds13. What is the main area of an OSPF network designated?Area 0 (zero)14. What is the command used to start OSPF routing on a router?Router(config)#router ospf [process ID]15. What is the processor ID?Its an identifier for the OSPF routing process on the router16. What is the command used to identify networks on an OSPF router?Router(config-router)#network [network no.] [wildcard-mask] area [area-id]17. What does an OSPF router use for its router ID? How can you force a differentID?It uses the highest active IP address on any of the interfaces (where OSPFis running). If you want to change the ID, set a Loopback interface with ahigher IP address so it will be forced to be the ID.18. What is a Loopback?It is a logical (virtual) interface; not a physical (real) one19. What is the command used to set a Loopback?Router(config)int Loopback[No.]Router(config-if) ip addr [IP number] [subnet mask]20. What is the recommended subnet mask to use on a Loopback interface? 3 All Modules - Revision Paul FlynnPage 1021. What is a priority number used for? How can you change it?If there is more than 1 router in the Area (broadcast multi-access), thenthere must be a DR and maybe a BDR for the Area. The priority number isused to determine which routers will be the DR and the BDR.You can change it with the following command:Router(config-if)#ip ospf [priority number]22. Why must you set the bandwidth on an interface running OSPF? What is thedefault bandwidth? How can you change it?Cost (the default metric of OSPF) uses bandwidth to determine the bestroute. The default is 1.544 Mbps. You can change it with the command:Router(config)#interface [type] [number]Router(config-if)#bandwidth [Kbps]23. How can OSPF routers authenticate each other?They exchange passwords that only other OSPF routers will know. Use thecommands below to set authentication:Router(config-if)#ip ospf authentication-key [password]Router(config-router)#area [area-number] authentication24. What is the difference between default authentication and a message-digestauthentication procedure? What is the command to do the latter?The default authentication sends the password in plain text; messagedigestencrypts the password thats sent.Router(config-if)#ip ospf authentication message-digest-key [key-id] md5[encryption-type key]Router(config-router)#area [area-id] authentication message-digest25. What is the relationship between the hello packet interval and the deadinterval? What is meant by the dead interval?The dead interval is 4 times the hello interval (e.g., hello is 10 seconds, sodead is 40 seconds).The dead interval is the time used to determine that a link is down, or dead.In other words, if a hello isnt received from a link for the space of 4 timesthe normal hello interval, its considered dead.CCNA 3 All Modules - Revision Paul FlynnPage 1126. What would happen if routers in the OSPF network have different hello intervalsconfigured?They wouldnt be able to talk to each other, so would be consideredinactive. Hello intervals must be the same on all the routers in the network.27. What is the best way to define a default route on an OSPF router?Use the quad zero command:Router(config)#ip route [interface or IP address of next hop]28. How can you make sure that this information is propagated to other routers in thearea?Router(config-router)#default-information originate29. List some of the show commands you can use to make sure that OSPF isfunctioning correctly.Show ip routeShow ip protocolShow ip ospf interfaceShow ip ospfShow ip ospf neighbor [detail] (shows neighbor database)Show ip ospf database (shows topological database)CCNA 3 All Modules - Revision Paul FlynnPage 12CCNA 3.0 Single Area OSPFBasic OSFP CommandsEnabling the OSPF processRouter(config)# router ospf process-idprocess-id:1 65,535Does not need to be the same as other routers.Enabling OSPF on the interfacesRouter(config-router)# network address wildcard-mask area area-idaddress wildcard-mask:The network address used to define the interfaces on which OSPF runs and to define the area ID forthose interfaces.The use of the wildcard-mask is the same as with ACLs.area-id:Specifies the area to associate with the network address.For Single Area OSPF, use an area-id of 0.Loopback and Router Priority CommandsConfiguring a Loopback interface for use as an OSPF Router IDRouter(config)# interface loopback numbernumber:1 65,535Extra: If the router-id command is used, this is the RouterID. (New command starting with IOS12.01).router ospf 1router-id ip-addressHighest Loopback interface is Router ID.If a Loopback interface is not configured, then the highest local active interface IP address is RouterID.For broadcast multi-access networks such as Ethernet and non-broadcast multicaccess networkssuch as Frame Relay, ATM, X.25, the router with the highest router ID is the DR, second highest isBDR.Configuring the OSPF priority of an interface to help determine DR/BDRRouter(config-if)# ip ospf priority numbernumber:0 255Highest priority become DR, second highest BDRPreempts Router-ID0 = Cannot become DR/BDRDefault = 1CCNA 3 All Modules - Revision Paul FlynnPage 13Modifying the OSPF Cost MetricExplicitly specifying the cost of sending a packet on an interfaceRouter(config-if)# ip ospf cost numbernumber:1 65,535A lower number represents a faster link.Default: The bandwidth metric is used in the formula, 108/bandwidthModifying the interface bandwidth metric used in the formula 108/bandwidthRouter(config-if)# bandwidth kilobitskilobits:Speed of the link in kilobits.Should be the same on both sides of a the link.Configuring OSPF AuthenticationSimple Authentication (plain text)Router(config-if)# ip ospf authentication-key passwordpasswordClear text unless message-digest is used.All neighboring routers on the same network must have the same password to be able to exchangeOSPF information.Must be the same between neighbors.Router(config-router)# area area-id authenticationarea-id:Specifies the area to associate with the authentication.For Single Area OSPF, use an area-id of 0.Encrypted AuthenticationRouter(config-if)# ip ospf authentication message-digest-key key-id md5 encryptiontypepasswordpasswordClear text unless message-digest is used.All neighboring routers on the same network must have the same password to be able to exchangeOSPF information.Must be the same between neighbors.key-id1 to 255must match on each router to authenticate.encryption-type0 to 70 is default7 is Cisco proprietary encryptionRouter(config-router)# area area-id authentication message-digestarea-id:Specifies the area to associate with the authentication.For Single Area OSPF, use an area-id of 0.CCNA 3 All Modules - Revision Paul FlynnPage 14Configuring OSPF TimersConfiguring the Hello timerRouter( config-if)# ip ospf hello-interval secondssecondsMust be same on neighboring routers.Default:o 10 seconds on broadcast networkso 30 seconds on non-broadcast networksConfiguring the Dead timerRouter (config-if)# ip ospf dead-interval secondssecondsMust be same on neighboring routers.Default:o 40 seconds on broadcast networkso 120 seconds on non-broadcast networksShould be 4 times the Hello timerPropagating a Default RouteConfigure a Static Default RouteRouter(config)# ip route interface|addressPropagate default route to other OSPF Routers (Configured only on the ASBR)Router(config-router)# default-information originate [always][always] (Optional)Will propagate a default route to other OSPF routers even if a static route is not configured on the ASBR.CCNA 3 All Modules - Revision Paul FlynnPage 15Show CommandsDisplaying the routing tableRouter# show ip route0 OSPF routesIA Inter-Area routesE1|E2 External routesDisplaying general information on the OSPF routing protocolRouter# show ip ospfDisplays:Router-IDProcess-IDSPF schedule delay timeSuccessive SPF hold timeAdjacent area information (CCNP)Displaying OSPF interface informationRouter# show ip ospf interfaceDisplays:Router-IDProcess-IDInterface costDR and BDR of this network if applicableHello and Dead timer intervalsDisplaying OSPF adjacent neighbor informationRouter# show ip ospf neighborDisplays neighbors:Router-IDIP addressInterface stateo Full when fully adjacento Full or 2-way for multi-access networksInterface priorityo Default = 1Debug CommandsDisplays OSPF adjacency processingRouter# debug ip ospf adjAdjacency informationHello processingDR/BDR electionAuthenticationSteps to OSPF operationsDisplays OSPF event processingRouter# debug ip ospf eventsAdjacency informationHello processingDR/BDR electionAuthenticationSteps to OSPF operationsCCNA 3 All Modules - Revision Paul FlynnPage 16CED255 INTERNETWORKING III, Ver. 3.0MODULE 3 STUDY GUIDE1. What is the difference between IGRP and EIGRP?EIGRP supports VLSM and CIDR, it has faster convergence times, its morescalable, and handles routing loops better than IGRP does.2. Why is EIGRP referred to as a hybrid protocol?Because it primarily is a distance vector protocol, but also has somecharacteristics of a link state protocol, such as sending hello packets,sending only partial updates (instead of entire table exchanges), and usingneighbor discovery. However, its easier to configure than OSPF.3. Can IGRP and EIGRP routers talk to each other? Why or why not?Yes, they can talk because EIGRP is simply an enhancement of IGRP;theyre still basically the same protocol.4. List the three tables that EIGRP maintains and briefly describe each one.Topology lists all routing tables in the AS; all learned routes are in thistableNeighbor lists adjacent routers, their addresses and interfacesRouting lists best route to each destination network5. List the five pieces of information found in the topology table and briefly describeeach one.Feasible distance The feasible distance (FD) is the lowest calculatedmetric to each destination.Route source The source of the route is the identification number of therouter that originally advertised that route. This field is populated only forroutes learned externally from the EIGRP network. Route tagging can beparticularly useful with policy-based routing.Reported distance The reported distance (RD) of the path is the distancereported by an adjacent neighbor to a specific destination.Interface information The interface though which the destination isreachableRoute status Routes are identified as being either passive (P), whichmeans that the route is stable and ready for use, or active (A), which meansthat the route is in the process of being recomputed by DUAL.CCNA 3 All Modules - Revision Paul FlynnPage 176. What is DUAL?The EIGRP distance vector algorithm is called the Diffusing UpdateAlgorithm (DUAL). DUAL tracks all the routes advertised by neighbors.Composite metrics of each route are used to compare them. DUAL alsoguarantees that each path is loop free. DUAL inserts lowest cost paths intothe routing table. These primary routes are known as successor routes. Acopy of the successor routes is also placed in the topology table.7. What is the difference between a feasible successor route and a :successorrouter?The successor route is the route in the routing table; in other words, theroute considered the best to the destination. The feasible successor is theback-up route, or the next-best route.8. What makes EIGRP able to support IP, IPX, and AppleTalk?It uses PDMs (protocol dependent modules). Also, for AppleTalk, it canactually act as the primarily protocol and AppleTalk doesnt even have tobe running.9. What is RTP? What does it do?Reliable Transport Protocol is a transport-layer protocol that can guaranteeordered delivery of EIGRP packets to all neighbors. This means EIGRPdoes not rely on TCP/IP to exchange routing information the way that RIP,IGRP, and OSPF do. To stay independent of IP, EIGRP uses RTP as its ownproprietary transport-layer protocol to guarantee delivery of routinginformation.10. What are the five EIGRP packet types? Briefly describe each one.Hello - discover, verify, and rediscover neighbor routersAcknowledgement - to indicate receipt of any EIGRP packet during areliable exchangeUpdate - used when a router discovers a new neighbor. An EIGRP routersends unicast update packets to that new neighbor, so that it can add to itstopology tableQuery - uses query packets whenever it needs specific information fromone or all of its neighborsReply - used to respond to a queryCCNA 3 All Modules - Revision Paul FlynnPage 1811. What are the commands used to start EIGRP running on a router?router(config)# router eigrp [autonomous-system-number]router(config-router)# network [network number]router(config)#int [type] [number]router(config-if)# bandwidth [kilobits]router(config-if)# eigrp log-neighbor-changes12. If you do not want to summarize routes, what is the command to turn it off? Whymight you not want to summarize (aggregate) routes?router(config-router)#no auto-summaryIf you have discontiguous subnets (subnets not right beside each other inthe numbering scheme), route summarization probably wont work right.13. List some of the show commands you can use to verify that EIGRP is ip routeshow ip eigrpshow ip protocolshow ip eigrp neighbor [details]show ip eigrp interfaceshow ip eigrp topologyshow ip eigrp traffic14. Which table built by EIGRP is considered the most important? List the fields ofinformation contained in this table and briefly describe each one.The neighbor table.Neighbor address network layer address of the neighbor routerHold time interval to wait without receiving anything from a neighborbefore considering the link unavailable. Originally, the expected packet wasa hello packet, but in current Cisco IOS software releases, any EIGRPpackets received after the first hello will reset the timer.Smooth Round-Trip Timer (SRTT) average time that it takes to send andreceive packets from a neighbor; used to determine the retransmit interval(RTO).Queue count (Q Cnt) number of packets waiting in a queue to be sent.Sequence Number (Seq No) number of the last packet received from thatneighbor; used to acknowledge a transmission of a neighbor and toidentify packets that are out of sequence.CCNA 3 All Modules - Revision Paul FlynnPage 1915. What is the most common problem that keeps RIP tables from updating?The use of VLSM and RIP v. 1, which doesnt support it.16. What is the most common type of networking problem?Layer 1 issues (cabling is the most prevalent)CCNA 3 All Modules - Revision Paul FlynnPage 20CED255 INTERNETWORKING III, Ver. 3.0MODULE 4 STUDY GUIDE1. Why is Ethernet described as a collision-prone network?Because of the nature of Ethernet. It is a broadcast technology, whichmeans that it is a shared technology where every packet is broadcast toevery device on the segment. It is also non-deterministic, which means anydevice can transmit at any time. This makes it prone to collisions.2. What networking device can help cut down or even eliminate collisions on anEthernet network? Why?A switch because every port on a switch acts like a mini-bridge, making it aseparate collision domain. Only those devices that are on that port of theswitch will be in the same collision domain. If each port goes to a separateworkstation or printer, then you basically will eliminate all collisions.3. What does the term microsegmentation mean?It is segmenting a network into point-to-point collision domains usingswitches, which gives maximum usage of bandwidth.4. Fill in the following table:Item LayerRouter 3Switch 2Bridge 2Passive hub 1Active hub 1Transceiver 1IP address 3MAC address 2Packets 3Frames 2Data segments 4Repeater 15. What is the most common LAN architecture used today?EthernetCCNA 3 All Modules - Revision Paul FlynnPage 216. Explain CSMA/CD. What does it stand for and how does it apply to Ethernetnetworks?Carrier Sense Multiple Access/Collision Detect: this is the technology thatEthernet is built on. Since Ethernet devices can transmit at will, CSMA/CDhas been built into them so that they will listen to the media first to see ifthere is any traffic on it before transmitting. This is how Ethernet tries toavoid collisions. However, if a collision occurs, it is detected very quicklyand all devices are told not to transmit for the back-off time to avoid morecollisions.7. What is meant by half-duplex technology?A device can either transmit or receive, but not both at the same time.8. What does the term latency mean?It is the delay the time a frame or a packet takes to travel from the sourcestation to the final destination. Latecncy is is inherent in different types ofnetworks and networking devices.9. What are the three sources of latency on an Ethernet network?First, there is the time it takes the source NIC to place voltage pulses onthe wire and the time it takes the receiving NIC to interpret these pulses.This is sometimes called NIC delay, typically around 1 microsecond for a10BASE-T NIC.Second, there is the actual propagation delay as the signal takes time toactually travel along the cable. Typically, this is about .556 microsecondsper 100 m for Cat 5 UTP. Longer cable and slower nominal velocity ofpropagation (NVP) results in more propagation delay.Third, latency is added according to which networking devices, whetherthey are Layer 1, Layer 2, or Layer 3, are added to the path between the twocommunicating computers. The actual transmission time, the duration oftime to actually send the bits, must also be included in understandingtiming on networks.10. What is meant by bit time in Ethernet networks?It is defined as the basic unit of time in which one bit can be sent.CCNA 3 All Modules - Revision Paul FlynnPage 2211. What is meant by the term attenuation when talking about data networks? Whatcauses it?Attenuation means that the signal weakens as it travels through thenetwork. The resistance in the cable or medium through which the signaltravels causes the loss of signal strength.12. What is meant by full duplex technology? Which Ethernet connections can takeadvantage of it? What does it take in order to create a full duplex network?It means that a device can both send and receive at the same time.Ethernet 10BASE-T, 100BASE-TX, or 1000BASE-Fx can use full duplex.A dedicated port on a switch that can support full duplex is required foreach node13. How many wires does it take to make a full-duplex cable? How much of thebandwidth is available on a full-duplex network?it takes two pairs for full duplex. 100% of the bandwidth in both directionsis available on full duplex because there is one pair of wires for sendingand another for receiving data.14. Is there an advantage of segmenting a network using switches instead of routers?Disadvantages?Yes, switches introduce less latency onto the network. They only add 10-30% latency; routers add 20-30% latency. However, switches only cansegment at Layer 2 to create separate collision domains; routers cansegment at Layer 3 (networks) and can subnet in separate networks.15. What is the main reason for LAN segmentation?It improves the performance of shared media (cuts down on collisiondomain size)16. Are there more or fewer collision domains in a microsegmented LAN? Why?There are more collision domains in a microsegmented LAN becauseswitches break a LAN down into smaller LANs by segmenting them. Thismakes smallerbut morecollision domains.17. What are the two main functions of switching devices?Switching data framesMaintaining switching operationsCCNA 3 All Modules - Revision Paul FlynnPage 2318. What type of circuits does a switched LAN create? What is one advantage of usingswitches on a LAN?virtual circuits. Switches create many small collision domains so collisionsare almost totally avoided, thus speeding up transmission.19. What is the difference between a symmetric and asymmetric switch?symmetric switches switch between like media (same bandwidth);asymmetric switches switch between unlike media (different bandwidths).20. Where does a switch store destination and transmission data? Describe thedifference between the two main types.In memory buffers in queues. In port-based memory buffering, packets arestored in queues that are linked to specific incoming ports. Shared memorybuffering deposits all packets into a common memory buffer which all theports on the switch share.21. What are the two switching methods? What are the main differences between thetwo?store-and-forward switching, cut-through switching. The main difference isthat store-and-forward waits until the entire frame has been received beforeit sends it on its way; cut-through switching reads the destination MACaddress on the incoming frame and immediately begins sending it onthrough (before the entire frame is received).22. What are the two sub-types of cut-through switching?Fast Forward only reads the destination MAC address and immediatelystarts forwarding the frameFragment Free makes sure there area at least 64 bytes of data to sendbefore forwarding the frame (anything less than 64 bytes is a fragment)23. What are the two main reasons to use of Ethernet switches in a network?Isolate traffic among segmentsAchieve greater amount of bandwidth per user by creating smaller collisiondomains24. What are the three main frame transmission modes used by Ethernet switches?Cut ThroughStore and ForwardFragment FreeCCNA 3 All Modules - Revision Paul FlynnPage 2425. What is the fourth mode? What is different about it?Adaptive cut-through With this mode, the switch uses cut-through until itdetects a given number of errors. Once the error threshold is reached, theswitch changes to store and forward mode. This method is sometimesreferred to as Error sensing26. What does a bridge use to forward data packets? How does it learn this information?They use MAC address to forward/not forward data packets to anothersegment. They learn new MAC addresses from the source address in theheader of a packet and add this info to a MAC table they build.27. How does a switch learn MAC addresses? What happens when a switch adds a newMAC address to its table?Switches learn MAC addresses from incoming packets. They add theseaddresses to their MAC tables so they can remember which segment hostswhich nodes. Each new address is time stamped so the switch candetermine which address are still good and which are old.28. What is Content-Addressable memory (CAM) used for in switch applications?To take out and process the address information from incoming datapacketsTo compare the destination address with a table of addresses stored withinit29. What do switches/bridges use to filter frames?They can filter frames based on any Layer 2 fields30. Can switches filter broadcast or multicast frames? Why or why not?Most Ethernet switches can filter broadcast and multicast frames, becausetoday, they are able to filter according to the network-layer protocol.CCNA 3 All Modules - Revision Paul FlynnPage 2531. What are the three ways of communicating on a data network? Briefly describe eachone.Unicast one transmitter tries to reach one receiverMulticast one transmitter tries to reach only a subset, or group, of theentire segment broadcastingBroadcast one transmitter tries to reach all the receivers in the network.The server station sends out one message and everyone on that segmentreceives the message.32. What is the MAC address for a broadcast message?FF:FF:FF:FF:FF:FFCCNA 3 All Modules - Revision Paul FlynnPage 26CED255 INTERNETWORKING III, Ver. 3.0MODULE 5 STUDY GUIDE33. What are the four components that make up a successful network design? Brieflydescribe each one.Functionality The network must work. The network must allow users tomeet their job requirements. The network must provide user-to-user anduser-to-application connectivity with reasonable speed and reliability.Scalability The network must be able to grow. The initial design shouldgrow without any major changes to the overall design.Adaptability The network must be designed with a vision toward futuretechnologies. The network should include no element that would limitimplementation of new technologies as they become available.Manageability The network should be designed to facilitate networkmonitoring and management to ensure ongoing stability of operation.34. To maximize bandwidth and availability of resources, what should you considerwhen designing a LAN?The function and placement of serversCollision detection issuesSegmentation issuesBroadcast domain issues35. What are the two main groups of servers? Give some examples of each would doand would be located.Enterprise DNS, e-mail, DHCP; located in Distribution Facilities (eitherMDF or IDFs)Application applications used by workers (Word, Excel, Accounting, etc.);located close to the users36. What are the steps you should follow in order to create a successful networkdesign?Gather requirements and expectationsAnalyze requirements and gathered dataDesign the Layer 1, 2, and 3 LAN structure, or topologyDocument the logical and physical network implementation37. What is meant by availability? Give some examples.Availability measures the usefulness of the network; it includesthroughput, response time, and access to resourcesCCNA 3 All Modules - Revision Paul FlynnPage 2738. What layers of the OSI model are you primarily working with when youre designinga network? What is involved at each layer?Layer 1 what type of media will be used in the networkLayer 2 how will the network be segmented at this layer; where willswitches be placed in the network?Layer 3 how will the network be subnetted (or will it be) and howshould those subnets be allowed to communicate; where shouldrouters be injected into the network?39. What are MDFs and IDFs? What would you find in them?They are wiring rooms (telecommunication rooms/distribution facilities).This is where all the networking devices (routers, switches, hubs, patchpanels, telephone connections, etc.) should be located. This is the endpointof your horizontal cabling.40. What is the difference between horizontal cabling and vertical cabling?Horizontal cabling runs from the workareas to the DF; backbone cabling isthe main cable running from floor-to-floor carrying the majority of the datato the major networking devices (switches and routers).41. List some of the documents you should create as you design and build your network.The exact locations of the MDF and IDF wiring closetsThe type and quantity of cabling used to interconnect the IDFs with theMDF, along with how many spare cables are available for increasing thebandwidth between the wiring closets.Detailed documentation of all cable runs, the identification numbers, andwhich port on the HCC or VCC the run is terminated onList of devices and their locationsThe IP addressing should be documented by site and by network within thesite. A standard convention should be set for addressing important hostson the network. This addressing scheme should be kept consistentthroughout the entire network. Addressing maps provide a snapshot of thenetwork.Physical maps of the network (helps to troubleshoot the network)CCNA 3 All Modules - Revision Paul FlynnPage 2842. What is the hierarchical design model? Why would you want to use it? What are thethree layers of this design model? Briefly describe each one.It is a design model that breaks a network into three distinct layers. It is agood idea to use a hierarchical design because this will make it easier tomake changes to the network as the organization grows. The three layersare:The Access Layer provides users in workgroups access to the networkThe Distribution Layer provides policy based connectivityThe Core layer provides optimal transport between sites. The core layeris often referred to as the backbone43. What layer of the OSI model do access switches run at? What are they designed todo? List a few of the Cisco models.They run at Layer 2 (although they have some Layer 3 characteristics) andtheir main purpose is to allow end users into the network. Some of theCisco models are 1900 series, 2950 series, 4000 series, and 5000 series.44. What layer of the OSI model do distribution switches run at? What are they designedto do? List a few of the Cisco models.Switches in this layer operate at Layer 2 and Layer 3 and they aggregate thewiring closet connections, define broadcast/multicast domains, allow VirtualLAN (VLAN) routing, create any media transitions that need to occur, and addsecurity to the network. Some of the models are 2926G, 5000 series, and 6000series.45. What layer of the OSI model do core switches run at? What are they designed todo? List a few of the Cisco models.Core switches are designed to use Layer 2 or Layer 3 switching and switchpackets as fast as possible and do not perform any packet manipulation, suchas access list filtering, which would slow down the network. An example of acore switch is an ATM switch. Some of the models include Catalyst 6500series, Catalyst 8500 series, IGX 8400 series, and Lightstream 1010.CCNA 3 All Modules - Revision Paul FlynnPage 29CED255 INTERNETWORKING III, Ver. 3.0MODULE 6 STUDY GUIDE1. What types of ports/interfaces does a configurable switch normally have?Ports (10/100/1000Mpbs) to connect devices; console port; higher speedports for backbone cables.2. What do the LEDs on the switch do?Alert you as to whether or not ports are working correctlyWhether power is being received into the switch from the powerconnectionWhether a remote power source is being used or notCurrent mode being used by switch3. What is a POST? When is it performed?Power On Self-Test. It is performed by the device upon power-up.4. What kind of cable is required to access the console port on a switch or router?Which port do you use? How do you know whats going on on the device?Roll over cable into the console port. You normally use a HyperTerminal orTelnet session from a PC to see what is happening on the device.5. Where is the power switch on a Cisco switch?There is none. You simply plug in the switch to the power source.6. What does CLI stand for? How does it differ on a Cisco switch from a router?Command line interface. It doesnt differ very muchthey both use theCisco IOS; the only thing thats a little different is the particular commandset available on each.7. List (in order) the EXEC modes on the Cisco switch.User EXECEnable/privileged EXECGlobal configuration EXECParticular configuration EXEC (e.g., interface, line, etc.)CCNA 3 All Modules - Revision Paul FlynnPage 308. What are the steps you should follow in order to completely configure a switch thatmay already have a configuration on it?Remove any existing VLAN information by deleting the VLAN database fileVLAN.dat from the flash directoryErase the back up configuration file startup-configReload the switch9. List some of the things you should configure on a switch to ensure it is secure, yeteasy to access for those authorized to do so.switch should be given a hostnamepasswords should be set on the console and vty linesIP addresses and a default gateway should be setIn a switch-based network, all internetworking devices should be in VLAN1, the management VLAN10. Identify what the following commands will do on the switch:Command PurposeSwitch#show mac-address-table Displays the MAC tableSwitch#clear mac-address-table Clears all entries out of the MAC tableand forces it to rebuild itselfSwitch(config)#mac-address-table static[mac address of host] interface[type][number] vlan [number or name]To set a static MAC address in the MACtableSwitch#show port security Display switch security on portsCCNA 3 All Modules - Revision Paul FlynnPage 31CED255 INTERNETWORKING III, Ver. 3.0MODULE 7 STUDY GUIDE1. What is meant by redundant technologies when talking about networks? Why orwhy not is this a good thing?Redundancy means to be in excess or exceeding what is usual and natural.Fault tolerance is achieved by redundancy. Normally, this is a good thingfor a network.2. What is a drawback of having a redundant switched topology?It may cause broadcast storms, multiple frame copies, and MAC addresstable instability problems. It is possible for switches to learn the wronginformation. A switch can learn that a MAC address is on a port when it isnot really on that port.3. What is the answer to this problem?To create a logical loop-free topology, which is called a tree. The SpanningTree Algorithm is used to span all the trees, thus creating a loop-freelogical topology.4. What is the IEEE standard for Spanning Tree? What does it specify802.1d; It specifies that the STP (spanning tree protocol) use the SpanningTree Algorithm (STA) to construct a loop free shortest path network.Shortest path is based on cumulative link costs. Link costs are based onthe speed of the link.5. What are BPDUs? What information contained in these BPDUs allow the switch tocreate the loop-free topology?The message that a switch sends allowing the formation of a loop freelogical topology is called a Bridge Protocol Data Unit (BPDU).Select a single switch that will act as the root of the spanning treeCalculate the shortest path from itself to the root switchFor each LAN segment, designate one of the switches as the closest one tothe root. This bridge is called the designated switch. The designatedswitch handles all communication from that LAN towards the root bridge.Each non-root switch chooses one of its ports as its root port. This is theinterface that gives the best path to the root switch.Select ports that are part of the spanning tree, the designated ports. Nondesignatedports are blocked.CCNA 3 All Modules - Revision Paul FlynnPage 326. What are the four elements that must exist on every switch in a spanned, switchednetwork?One root bridge per networkOne root port per non root bridgeOne designated port per segmentNon designated ports are unused7. Which switch will become the root bridge in a network running STP?The switch with the smallest BID (bridge ID) number.8. How often are BPDUs sent out by default?Every 2 seconds9. What are the five STP states? Briefly describe each one.blocking state - ports can only receive BPDUs; data frames are discardedand no addresses can be learnedlistening state - switches determine if there are any other paths to the rootbridge (called the forward delay)learning state - user data is not forwarded, but MAC addresses are learnedfrom any traffic that is seen (also called the forward delay)forwarding state - user data is forwarded and MAC addresses continue tobe learned; BPDUs are still processeddisabled state - occurs when an administrator shuts down the port or theport fails10. What is the definition of a converged switched internetwork?When all the switch and bridge ports are in either the forwarding or blockedstate11. What does the 802.1w standard define?Rapid Spanning Tree ProtocolCCNA 3 All Modules - Revision Paul FlynnPage 33CED255 INTERNETWORKING III, Ver. 3.0MODULE 8 STUDY GUIDE1. What is the definition of a VLAN?A VLAN is a group of network services that is not restricted to a physicalsegment or switch. VLANs logically segment switched networks based onan organization's functions, project teams, or applications as opposed to aphysical or geographical basis.2. Is a VLAN able to contain broadcasts?Yes, a VLAN may be thought of as a broadcast domain that exists within adefined set of switches3. How does a switch that has multiple VLANs on it switch frames that come into it?The switch maintains a separate bridging table for each VLAN, so if a framecomes in on a port in VLAN 1 the switch searches the bridging table forVLAN 1When the frame is received, the switch adds the source address to thebridging table if it is currently unknown.The destination is checked so a forwarding decision can be made.For learning and forwarding the search is made against the address tablefor that VLAN only.4. What are the three main ways that VLANs are organized?Port-centric, statically, dynamically5. List some of the advantages of VLANning a network.Easily move workstations on the LAN.Easily add workstations to the LAN.Easily change the LAN configuration.Easily control network traffic.Improve security.6. What are the three basic models for determining and controlling how a packet getsassigned to a VLAN?Port-based VLANS.MAC address based VLANs.Protocol based VLANsCCNA 3 All Modules - Revision Paul FlynnPage 347. What happens to the frame header when using any of the above models?A VLAN ID is inserted into it before the frame is transmitted onto the linkbetween the VLANs.8. What is the most used frame tagging option used in switching? What is specialabout this?Inter-Switch Link (ISL); its a Cisco-proprietary protocol that maintainsVLAN information as traffic flows between switches and routers.9. How can you make an ATM network look like an Ethernet network?LAN emulation (LANE) is a way to make an Asynchronous Transfer Mode(ATM) network simulate an Ethernet network10. What type of address must be assigned to each VLAN?A unique Layer 3 network address11. What characteristics should an end-to-end VLAN network comprises?Users are grouped into VLANs independent of physical location, butdependent on group or job function.All users in a VLAN should have the same 80/20 traffic flow patterns.As a user moves around the campus, VLAN membership for that usershould not change.Each VLAN has a common set of security requirements for all members.12. What does standard 802.1q pertain to?Fast Ethernet Inter-Switch Link (ISL), which is used to carry multiple VLANinformation between the wiring closets and the distribution layer switches.13. What is meant by a static VLAN? What are some advantages/disadvantages of thismethod?Ports on a switch are manually assigned to a VLAN by using a VLANmanagement application or by working directly within the switch.Advantage is that theyre very secure and easy and straightforward toconfigure; disadvantage is that they must be configured and updatedmanually by an administrator.CCNA 3 All Modules - Revision Paul FlynnPage 3514. What is meant by a dynamic VLAN? What are some advantages/disadvantages ofthis method?Do not rely on ports assigned to a specific VLAN. Instead, VLANassignment is based on MAC addressing, logical addressing, or protocoltype. Advantage is that the switch takes care of VLAN switching andtagging based on the protocols being used. Disadvantage is that theprotocol must be robust enough to maintain the switched network.15. Complete the table for the commands used to configure a VLAN on a 2900 seriesCatalyst switch.Command PurposeSwitch#show version Displays the version of IOS running on theswitchSwitch#vlan database Enter the VLAN configuration modeSwitch(vlan)#vlan [vlan number] Assign a number to the VLAN to createSwitch(config)#interface [type] [port] Identify which interface to assign VLAN toSwitch(config-if)#switchport access vlan[vlan number]Assign VLAN to one or more interfacesSwitch#show vlan [brief] Verify VLAN assignment(s)Switch#show vlan id [vlan number] Verify VLAN assignmentSwitch#show running-config Display the switchs configuration fileSwitch(vlan)#no vlan [vlan number] Delete a VLANSwitch#show spanning-tree Display the spanning tree topology knownto the routerSwitch#debug sw-vlan packets Display general information about VLANpackets that the router received but is notconfigured to support16. What are the steps you should follow to troubleshoot problems with your VLANs?1. Check the physical indications, such as LED status.2. Start with a single configuration on a switch and work outward.3. Check the Layer 1 link.4. Check the Layer 2 link.5. Troubleshoot VLANs that span several switches.17. What is a broadcast storm?A broadcast storm occurs when a large number of broadcast packets arereceived on a port. Forwarding these packets can cause the network toslow down or to time out. Storm control is configured for the switch as awhole, but operates on a per-port basis. By default, storm control isdisabled.CCNA 3 All Modules - Revision Paul FlynnPage 3618. How can they be prevented?By the use of high and low thresholds to discard excessive broadcast,multicast, and unicast MAC traffic. Also the switch can be set to shut downthe port when the rising threshold is reached.CCNA 3 All Modules - Revision Paul FlynnPage 37CED255 INTERNETWORKING III, Ver. 3.0MODULE 9 STUDY GUIDE1. What is the definition of a trunk in a switched network?A physical and logical connection between two switches across whichnetwork traffic travels. A trunk is a single transmission channel betweentwo points that are usually switching centers.2. What is a trunk designed to do if there are multiple VLANs in a network?The purpose of a trunk is to save ports when creating a link between twodevices implementing VLANs, typically two switches.3. What are trunking protocols designed to do? What are the two types of trunkingmechanisms? Which has become the standard? Why?To effectively manage the transfer of frames from different VLANs on asingle physical line. The trunking protocols establish agreement for thedistribution of frames to the associated ports at both ends of the trunk.Trunking mechanisms: frame filtering and frame taggingFrame tagging has been adopted as the standard trunking mechanism byIEEE because it is more scalable than frame filtering.4. How does frame tagging work?Frame tagging places a unique identifier in the header of each frame as it isforwarded throughout the network backbone. The identifier is understoodand examined by each switch before any broadcasts or transmissions aremade to other switches, routers, or end-station devices. When the frameexits the network backbone, the switch removes the identifier before theframe is transmitted to the target end station. Frame identificationfunctions at Layer 2 and requires little processing or administrativeoverhead.5. What is the first step you must perform on a switch before starting trunking?Configure the port first as a trunk and then specify the trunk encapsulationCCNA 3 All Modules - Revision Paul FlynnPage 386. Complete the following table:Command PurposeSwitch(config-if)#switchport mode trunk Turns on trunking modeSwitch(config-if)#switchport trunkencapsulation [dot1q | isl]Specifies encapsulation type on port witheither 802.1a or ISLSwitch#show port capabilities Displays what the port can do, includingwhat encapsulation the port can supportSwitch#show trunk [mod_num/port_num] Displays if trunking has been configuredand the settingsSwitch#erase startup-configuration Clears NVRAM of any saved configurationfilesSwitch(vlan)#vtp v2-mode Sets the VTP version to Version 2Switch(vlan)#vtp domain [name] Creates a management domainSwitch#show vtp status Displays VTP configuration and statusSwitch(vlan)#vtp [client | server | transparent] Sets the correct mode of the switchSwitch#show vtp counters Displays statistics about advertisementssent and received on the switchRouter(config)#interface fastethernet [portnumber.subinterface-number]Identifies which port and/or subinterfaceyou wish to configureRouter(config-if)#encapsulation dot1q [vlannumber]Set encapsulation for 802.1q on aninterfaceRouter(config-if)#ip address [ip-address][subnet-mask]Sets the IP address on an interface7. What does it mean if the trunking mode has been set to negotiate?Puts the port into permanent trunking mode but prevents the port fromgenerating Dynamic Trunking Protocol (DTP) frames. You must configurethe neighboring port manually as a trunk port to establish a trunk link.8. What is VTP? Why should it be used on a VLANed network?VLAN Trunking Protocol (VTP) was created to solve potential operationalproblems in a VLANs network switched environment. The role of VTP is tomaintain VLAN configuration consistency across a common networkadministration domain. VTP is a messaging protocol that uses OSI Layer 2trunk frames to manage the addition, deletion, and renaming of VLANs on asingle domain. Further, VTP allows for centralized changes that arecommunicated to all other switches in the network.9. What is a VTP domain?A VTP domain is made up of one or more interconnected devices thatshare the same VTP domain name.CCNA 3 All Modules - Revision Paul FlynnPage 3910. What are the four items found in a VTP message?VTP protocol version: Either Version 1 or 2VTP message type: Indicates one of four typesManagement domain name length: Indicates size of the name that followsManagement domain name: The name configured for the managementdomain11. What are the three modes that switches can work in when running VTP? Brieflydescribe each one.Server - can create, modify, and delete VLAN and VLAN configurationparameters for the entire domain. VTP servers send VTP messages out toall trunk ports.Client - cannot create, modify, or delete VLAN information. VTP clients doprocess VLAN changes and send VTP messages out to all trunk ports.Transparent - forward VTP advertisements such as version 2, but ignoreinformation contained in the message. A transparent switch will not modifyits database when updates are received, nor will the switch send out anupdate indicating a change in its VLAN status. Except for forwarding VTPadvertisements, VTP is disabled on a transparent switch.12. What are the two types of VTP advertisements?Requests from clients that want information at bootupResponse from servers13. What are the three types of VTP messages?Advertisement requestsSummary advertisementsSubset advertisements14. What kinds of activities can trigger a VTP advertisement?Creating or deleting a VLAN, suspending or activating a VLAN, changingthe name of a VLAN, changing the maximum transmission unit (MTU) of aVLAN15. What are the two versions of VTP available now? Which is the default version? Arethey interoperable?Version 1 and Version 2. Version 1 is the default; they are notinteroperable.CCNA 3 All Modules - Revision Paul FlynnPage 4016. Can VLANs communicate directly with one another? Why or why not?No, they must still go through a router to communicate. Routers aredesigned to connect networks, which is what VLANs are.17. What is meant by a router on a stick?A trunk line, which can support multiple VLANs, is the physical connectionto a router. This topology is called a router on a stick because there is asingle connection to the router. However, there are really multiple logicalconnections between the router and the switch, based on how manyVLANs run through the trunk.18. What is a subinterface? How are they used on a switch?The logical division of a physical interface into several logical interfaces.Each subinterface of a port can support a separate VLAN and is assigned adifferent IP address.