ActualTests.Cisco.640-802.Exam.Q.and.A.08.15.08-DDU (1130589), страница 79
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AAL 5 SNAP is an ATM encapsulation and is not related to frame relay.QUESTION 697:In Frame Relay; what is the purpose of Inverse ARP? (Select only one answerchoice)A. It is used to map a known IP address to a MAC addressB. It is used to map a known DLCI to a MAC addressC. It is used to map a known MAC address to an IP addressD. It is used to map a known DLCI to an IP addressE. It is used to map a known MAC address to DLCIActualtests.com - The Power of Knowing640-802F. None of the aboveAnswer: DExplanation:Just as ARP resolves IP addresses to MAC addresses, Inverse ARP maps a known DLCIto an IP address.Incorrect Answers:A, C: ARP and Reverse ARP (RARP) are used for IP address/MAC address mappings.B, E: DLCI do not have a need to discover the MAC address of a host, so a DLCI isnever mapped to a MAC address.QUESTION 698:In regard to a default Frame-Relay data network, what kind of physical network isit classified as?A.
Point-to-pointB. Broadcast multi-accessC. Nonbroadcast multipointD. Nonbroadcast multi-accessE. Broadcast point-to-multipointF. None of the aboveAnswer: DExplanation:Frame relay networks are considered to be NBMA networks. Frame Relay is a WANprotocol that operates at the physical and data link layers of the Open SystemInterconnection (OSI) reference model. This protocol is standardized by both theInternational Telecommunication Union Telecommunications Standardization Sector(ITU-T) and American National Standards Institute (ANSI).Frame Relay uses statistical multiplexing techniques to provide network access in apacket-switched network. It is strictly a Layer 2 protocol suite. Being a Layer 2 protocolenables Frame Relay to offer higher performance WAN applications (such as LANinterconnection) than the older protocols (such as X.25), which incorporated Layer 3functions.
Given these performance benefits, Frame Relay is a popular WAN medium.However, it has some limitations with regard to IP multicast. To illustrate, Frame Relayis a Layer 2 nonbroadcast multiaccess (NBMA) network protocol. IP multicast networksare designed to utilize the capabilities of Layer 2 broadcast media such as on a LAN.QUESTION 699:Which of the following statements correctly describes the characteristics of a FrameActualtests.com - The Power of Knowing640-802Relay point-to-point subinterface? (Select two answer choices)A. Needs to use Inverse ARP.B.
Maps a single IP subnet per DLCI.C. Maps a single IP subnet across multiple DLCIs.D. Resolves NBMA (non broadcast multi access) split horizon issues.E. Requires use of the frame-relay map command.F. None of the aboveAnswer: B, DExplanation:B is correct because only one DLCI can be configured per point-to-point subinterface.The command 'frame-relay interface-dlci' associates the selected point-to pointsubinterface with only one DLCI.Subinterfaces were originally created to take care of split-horizon issues from distancevector routing protocols over non-broadcast multiple access networks, because splithorizon prevents routing updates received on one interface from retransmitting out ontothe same interface.
This is true even if the routing update is received on one frame relayPVC destined out to another frame relay PVC! By partitioning the frame relay networkinto numerous point-to point networks using subinterfaces; each new point-to-pointsubnetwork gets their own network number assigned. Therefore, the routed protocolviews each subnetwork as if it was located on a separate interface.Incorrect Answers:A. Since only one DLCI is assigned per subnet in a logical point to point interface, thereis no need for Inverse ARP, since both the DLCI and IP addresses are already known.C.
The IP subnet is mapped across a single virtual circuit, so only one DLCI is mappedActualtests.com - The Power of Knowing640-802per subinterface.E. This command would be needed when multiple virtual circuits are being configured onone physical interface. When logical subinterfaces are used, the "frame-relayinterface-dlci" command is used, not this command.Reference: http://www.ciscopress.com/articles/article.asp?p=170741&seqNum=6QUESTION 700:Regarding Frame Relay Multipoint subinterfaces; which statement is true?A. An IP address is required on the physical interfaceB.
All routers are required to be fully meshedC. All routers must be in the same subnet to forward routing updates and broadcastsD. Multipoint is the default configuration for Frame Relay subinterfacesE. None of the aboveAnswer: CExplanation:Unlike Frame Relay point-to-point connections, multipoint Frame Relay router interfacesmust all be in the same subnet. With multipoint, a single subinterface is used to establishmultiple PVC connections to multiple physical interfaces or subinterfaces on remoterouters.
In this case, all the participating interfaces are in the same subnet, and eachinterface has its own local DLCI. Because the subinterface is acting like a regular NBMAFrame Relay network in this environment, broadcast traffic is subject to the split horizonrule.Incorrect Answers:A. The IP address is required on the logical subinterface, not the physical interface.B.
It is never an absolute requirement for a frame relay network to be fully meshed. Thevast majority of frame relay networks are configured in a hub and spoke fashion, to avoidall of the charges associated with the numerous PVC's needed to be fully meshed.D. Point to point is the default frame relay subinterface type.QUESTION 701:The Certkiller Frame Relay network is displayed below:Actualtests.com - The Power of Knowing640-802In regard to router Certkiller 1; what is the function of the Frame Relay DLCI?A. Defines the signaling standard between Certkiller 1 and Certkiller 2.B.
Classifies the encapsulation used between Certkiller 1 and Certkiller 2.C. Identifies the circuit between Certkiller 2 and the frame switch.D. Classifies the circuit between Certkiller 1 and Certkiller 2.E. Defines the signaling standard between Certkiller 1 and the frame switch.Answer: CExplanation:Certkiller 1 sends frames with DLCI, and they reach the local switch. The local switchsees the DLCI field and forwards the frame through the Frame Relay network until itreaches the switch connected to Certkiller 2. The Certkiller 2's local switch forwards theframe out of the access link to Certkiller 2. DLCI information is considered to be locallysignificant, meaning that the DLCI is used between the end router and the carrier's localframe relay switch.Reference: CCNA Self-Study CCNA ICND exam certification Guide (Cisco Press,ISBN 1-58720-083-X) Page 386Incorrect Answers:A, E.
DLCI is used only as a circuit identifier (DLCI=Data Link Circuit Identifier), andnot used for signaling.B. The encapsulation options are not defined with DLCIs.D. The DLCI information is considered to be locally significant, meaning that the DLCIis used between the end router and the carrier's local frame relay switch. The DLCI is notused end to end (router to router).QUESTION 702:Your frame relay network uses DLCI information on each of the PVC's. What is thepurpose of them?A. They determine the encapsulation type employed by the Frame Relay.B. They identify the logical circuit between a local router and a Frame Relay WANswitch.C.
They represent the physical address of the router.D. They represent the keepalives in the maintenance of PVC.Answer: BExplanation:Routers use the data-link connection identifier (DLCI) as the Frame Replay address,which identifies the VC over which the frame should travel.Data Link Connection Identifiers are the "hardware address" on a Frame Relay network.They identify a routers PVC to the Frame Relay switch.Actualtests.com - The Power of Knowing640-802Incorrect Answers:A. DLCI information is not used to determine the encapsulation of the frame relay circuitin any way.C. A DLCI is used at layer two, but it is a separate identifier that is not related to thehardware MAC address of any device.D.
The function of a keepalive is handled by LMI in a frame network, not the DLCI.Reference:CCNA Self-Study CCNA ICND exam certification Guide (Cisco Press, ISBN1-58720-083-X) page 377QUESTION 703:The Certkiller international frame relay network is shown below:The Frame Relay circuit between Mexico and Canada is experiencing congestion.Which types of notification are used to alleviate the congestion? (Choose three.)A. FECNB. CIRC. BECND. DEE.
DLCI 100 is downF. DLCI 200 is downAnswer: A, C, DExplanation:In a frame relay network, FECN (forward explicit congestion notification) is a header bittransmitted by the source (sending) terminal requesting that the destination (receiving)terminal slow down its requests for data. BECN (backward explicit congestionnotification) is a header bit transmitted by the destination terminal requesting that thesource terminal send data more slowly. FECN and BECN are intended to minimize thepossibility that packets will be discarded (and thus have to be resent) when more packetsActualtests.com - The Power of Knowing640-802arrive than can be handled.If the source terminal in a communications circuit generates frequent FECN bits, itindicates that the available network bandwidth (at that time) is not as great as can besupported by the destination terminal.
Likewise, if the destination generates frequentBECN bits, it means the available network bandwidth (at that time) is not as great as canbe supported by the source. In either case, the root cause is lack of available bandwidth atthe times during which FECN or BECN bits are generated. This can occur because ofoutdated or inadequate network infrastructure, heavy network traffic, high levels of linenoise, or portions of the system going down. Identifying and resolving these issues canimprove overall network performance, especially when the system is called upon to carrya large volume of traffic.Discard Eligibility (DE)When there is congestion on the line, the network must decide which frames to discard inorder to free the line.
Discard Eligibility provides the network with a signal to determinewhich frames to discard. The network will discard frames with a DE value of 1 beforediscarding other frames.The DE bit may be set by the user on some of its lower-priority frames. Alternatively, thenetwork may set the DE bit to indicate to other nodes that a frame should bepreferentially selected for discard, if necessary.QUESTION 704:Exhibit:Please study the exhibit carefully.
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