Pass4sure practice exam No.7
7.The command frame-relay map ip 10.121.16.8 102 broadcast was entered on the router. Which of the following statements is true concerning this command?
A: This command should be executed from the global configuration mode.
B: The IP address 10.121.16.8 is the local router port used to forward data.
C: 102 is the remote DLCI that will receive the information.
D: This command is required for all Frame Relay configurations.
E: The broadcast option allows packets, such as RIP updates, to be forwarded across the PVC.
Correct Answers: E
The question tests the CISCO candidatesa?? understanding on the static mapping of Frame-relay. The command frame-relay map ip 10.121.16.8 102 broadcast was entered on the router. Which of the following statements is true concerning this command?
The candidates who are familiar with Frame-relay all know that the command is configured to the router under the interface mode, but option A said the order command is configured in the global mode, it is obviously wrong;
For the command of frame-relay map ip 10.121.16.8 102 broadcast, it means to mapping the distal IP to the local DLCI. Option B said this IP is the local routers’ IP, while option C said 102 of DLCI is remote one, it is obvious that B and C are wrong options;
For option D, not all of the Frame-relay needs configuration, for example, when the Frame-relay supports Reverse ARP analyze, the command would not need configuration, the D is also wrong.
Pass4sure practice exam No.24
24.Refer to the exhibit. Which statement describes DLCI 17?
A: DLCI 17 describes the ISDN circuit between R2 and R3.
B: DLCI 17 describes a PVC on R2. It cannot be used on R3 or R1.
C: DLCI 17 is the Layer 2 address used by R2 to describe a PVC to R3.
D: DLCI 17 describes the dial-up circuit from R2 and R3 to the service provider.
Correct Answers: C
Refer to the exhibit, the interfaces of R2 are configured with FR, and designated DLCI with No. 17. The role of DLCI is that when there are data sent out from R2 to R3, which PVC should be handed over the data.
1, Question
Now to configure a related command of frame-relay to the router: frame-relay map ip 10.121.16.8 102 broadcast.
2, requirements
For the describing of the options, which is correct in the following statement about the parameters of the command?
Frame-relay technology belongs to WAN technology, but its core reference model is still the standard, then it is our OSI. (Here, I would like to reiterate once again the importance of the OSI model; the candidates must master it well) Why we should configure map ip in interface? This command corresponds to which layer functions of OSI?
The command of map ip is to configure the Mapping of “agreement - address” to the link of frame-relay. Speaking of the mapping of “agreement - address”, we will naturally remember the ARP in Ethernet. We take the work mechanism of ARP as the reference, and then start analysis on command’s parameters in map ip of frame-relay.
In common Ethernet environment, and when host A wants to communicate with a network-paragraph host B, host A will start to Packaging data with top-down order, if A knows host B’s IP address is 192.168.1.2 then when it packages the data packet in the network layer, it will complete the packet header successfully, but when the data packets to continue Packaging to the bottom, there will be a problem - what’s the physical address of host B? ? ? In the second layer, the addressing is achieved through the MAC address. At this point, there is no way of knowing the target MAC address, and Packaging becomes impossible. One solution is using ARP. When A wants to communicate with B, A will check its ARP cache Table at first to see if there is a mapping record about agreements address of B(the relationship of mapping from IP to MAC) and, if so, access to data package directly; If not, send a broadcast report of goal Address with the entire text of F at first, to search B’s MAC address from the network’s, after received the Unicast response of B, then A will record the information in the A ARP cache table.
In a same link, it is not enough to just know each other’s network layer address for the two sets of equipments; they also need to know the addressing information between the two layers. Frame-relay technology is the connection-oriented transport protocol which works in the second layer; it requires addressing information of Layer 2 and Layer 3 to communicate the two sites through PVC. Different from Ethernet, its second layer information is not the MAC of a specific host, but DLCI (Data Link Connection Identifier).
We can use two methods to enable the mapping agreement addresses maintain normal relations.
1, To configure it through hand static.
The command is showed as the sample
Frame-relay map: This mapping command can create a mapping reached remote agreement address in static.
As detailed in the next example:
2, Use of frame-relay reverse ARP (Inverse ARP)
Frame-relay reverse ARP will provide the method to connect the address of the distal third layer and the DLCI of the local second layer through a non-manual way.
Pass4sure practice exam No.64
64.Refer to the exhibit. What is the meaning of the term dyn
mic as displayed in the output of the show frame-relay map command shown?
A: The Serial0/0 interface is passing traffic.
B: The DLCI 100 was dynamically allocated by the router.
C: The Serial0/0 interface acquired the IP address of 172.16.3.1 from a DHCP server.
D: The DLCI 100 will be dynamically changed as required to adapt to changes in the Frame Relay cloud.
Answer B
The status of router frame-relay interfaces can be checked by the command of “show frame-relay map” . In above exhibit, dynamic means the mapping relations of dlci and ip is achieved through Inverse ARP access to the dynamic. So the correct answer is B.
