CCNA – WAN 2
Here you will find answers to WAN Questions – Part 2
If you are not sure about Frame Relay, please read my Frame Relay tutorial.
Question 1
Users have been complaining that their Frame Relay connection to the corporate site is very slow. The network administrator suspects that the link is overloaded. Based on the partial output of the Router#show frame relay pvc command shown in the graphic, which output value indicates to the local router that traffic sent to the corporate site is experiencing congestion?
A. DLCI=100
B. last time PVC status changed 00:25:40
C. in BECN packets 192
D. in FECN packets 147
E. in DF packets 0
Answer: C
Explanation
First we should grasp the concept of BECN & FECN through an example:
Suppose Router A wants to send data to Router B through a Frame Relay network. If the network is congested, Switch 1 (a DCE device) will set the FECN bit value of that frame to 1, indicating that frame experienced congestion in the path from source to destination. This frame is forwarded to Switch 2 and to Router B (with the FECN bit = 1).
Switch 1 knows that the network is congesting so it also sends frames back to Router A with BECN bit set to 1 to inform that path through the network is congested.
In general, BECN is used on frames traveling away from the congested area to warn source devices that congestion has occurred on that path while FECN is used to alert receiving devices if the frame experiences congestion.
BECN also informs the transmitting devices to slow down the traffic a bit until the network returns to normal state.
The question asks “which output value indicates to the local router that traffic sent to the corporate site is experiencing congestion” which means it asks about the returned parameter which indicates congestion -> BECN.
Question 2
When troubleshooting a Frame Relay connection, what is the first step when performing a loopback test?
A. Set the encapsulation of the interface to HDLC.
B. Place the CSU/DSU in local-loop mode.
C. Enable local-loop mode on the DCE Frame Relay router.
D. Verify that the encapsulation is set to Frame Relay.
Answer: A
Explanation
The first thing when performing a loopback test on a Frame Relay connection is to reconfigure the encapsulation of the interface to HDLC protocol instead of Frame Relay protocol. The main reason is Frame Relay requires a pair of DCE/DTE which cannot be used in a loopback test.
For more information about steps of trouble shooting Frame Relay, please read: http://www.cisco.com/en/US/tech/tk713/tk237/technologies_tech_note09186a008014f8a7.shtml#topic20
For your information, below is a paragraph quoted from the above link:
“Serial0 is down, line protocol is down”
This output means you have a problem with the cable, channel service unit/data service unit (CSU/DSU), or the serial line. You need to troubleshoot the problem with a loopback test. To do a loopback test, follow the steps below:
1. Set the serial line encapsulation to HDLC and keepalive to 10 seconds. To do so, issue the commands encapsulation hdlc and keepalive 10 under the serial interface.
2. Place the CSU/DSU or modem in local loop mode. If the line protocol comes up when the CSU, DSU or modem is in local loopback mode (indicated by a “line protocol is up (looped)” message), it suggests that the problem is occurring beyond the local CSU/DSU. If the status line does not change states, there is possibly a problem in the router, connecting cable, CSU/DSU or modem. In most cases, the problem is with the CSU/DSU or modem.
3. Ping your own IP address with the CSU/DSU or modem looped. There should not be any misses. An extended ping of 0×0000 is helpful in resolving line problems since a T1 or E1 derives clock from data and requires a transition every 8 bits. B8ZS ensures that. A heavy zero data pattern helps to determine if the transitions are appropriately forced on the trunk. A heavy ones pattern is used to appropriately simulate a high zero load in case there is a pair of data inverters in the path. The alternating pattern (0×5555) represents a “typical” data pattern. If your pings fail or if you get cyclic redundancy check (CRC) errors, a bit error rate tester (BERT) with an appropriate analyzer from the telco is needed.
4. When you are finished testing, make sure you return the encapsulation to Frame Relay.
Question 3
What occurs on a Frame Relay network when the CIR is exceeded?
A. All TCP traffic is marked discard eligible.
B. All UDP traffic is marked discard eligible and a BECN is sent.
C. All TCP traffic is marked discard eligible and a BECN is sent.
D. All traffic exceeding the CIR is marked discard eligible.
Answer: D
Explanation
Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the Frame Relay switch. Frames that are sent in excess of the CIR are marked as discard eligible (DE) which means they can be dropped if the congestion occurs within the Frame Relay network.
Note: In the Frame Relay frame format, there is a bit called Discard eligible (DE) bit that is used to identify frames that are first to be dropped when the CIR is exceeded.
Question 4
What are two characteristics of Frame Relay point-to-point subinterfaces? (Choose two)
A. They create split-horizon issues.
B. They require a unique subnet within a routing domain.
C. They emulate leased lines.
D. They are ideal for full-mesh topologies.
E. They require the use of NBMA options when using OSPF.
Answer: B C
Question 5
The output of the show frame-relay pvc command shows ”PVC STATUS=INACTIVE”. What does this mean?
A. The PVC is configured correctly and is operating normally,but no data packets have been detected for more than five minutes.
B. The PVC is configured correctly, is operating normally and is no longer actively seeking the address the remote route,
C. The PVC is configured correctly, is operating normally and is waiting for interesting to trigger a call to the remote router.
D. The PVC is configured correctly on the local switch, but there is a problem on the remote end of the PVC.
E. The PVC is not configured on the switch.
Answer: D
Explanation
The PVC STATUS displays the status of the PVC. The DCE device creates and sends the report to the DTE devices. There are 4 statuses:
+ ACTIVE: the PVC is operational and can transmit data
+ INACTIVE: the connection from the local router to the switch is working, but the connection to the remote router is not available
+ DELETED: the PVC is not present and no LMI information is being received from the Frame Relay switch
+ STATIC: the Local Management Interface (LMI) mechanism on the interface is disabled (by using the “no keepalive” command). This status is rarely seen so it is ignored in some books.
Question 6
Which encapsulation type is a Frame Relay encapsulation type that is supported by Cisco routers?
A. Q933-A Annex A
B. IETF
C. ANSI Annex D
D. HDLC
Answer: B
Explanation
Cisco supports two Frame Relay encapsulation types: the Cisco encapsulation and the IETF Frame Relay encapsulation, which is in conformance with RFC 1490 and RFC 2427. The former is often used to connect two Cisco routers while the latter is used to connect a Cisco router to a non-Cisco router. You can test with your Cisco router when typing the command Router(config-if)#encapsulation frame-relay ? on a WAN link. Below is the output of this command (notice Cisco is the default encapsulation so it is not listed here, just press Enter to use it).
Note: Three LMI options are supported by Cisco routers are ansi, Cisco, and Q933a. They represent the ANSI Annex D, Cisco, and ITU Q933-A (Annex A) LMI types, respectively.
HDLC is a WAN protocol same as Frame-Relay and PPP so it is not a Frame Relay encapsulation type.
Question 7
Router A is unable to reach Router B. Both routers are running ios version 12.0. After reviewing the command output and graphic, what is the most likely cause of the problem?
A. incorrect bandwidth configuration
B. incorrect LMI configuration
C. incorrect map statement
D. incorrect IP address
Answer: C
Explanation
With this topology and the DLCI, we can only think of “incorrect map statement”. From the topology we can deduce traffic with a DLCI of 75 will be sent to 192.168.2.1 but the text below wrongly shows “DLCI 50″ for the next router 192.168.2.1 -> C is correct.
The map statement is correct for router A it should have the next hop ip address and what ever DLCI it wants, DLCI’s are only locally significant, as per your own tutorial. So C is not correct, unless it is the output from Router B and not Router A. If it is the output from router b then the question should specify.
The most likely cause of the problem for me is “incorrect IP address”. As we know, frame relay is a logical point-to-point connection so each end of the connection must be in the same IP subnet. I don’t see any problem with the map statement because the local DLCI 50 is map to the remote router’s IP Address of 192.168.2.1.
So for me I go with D (incorrect IP address)
I Agree with Jeff, can somebody please confirm if either this is correct or incorrect in the actual exam?
anybody aware with the answer of the following question..
refer to the exhibit. Router interface is being configured for frame relay.
However, as the exhibit shows, the router will not accept the command to configure the LMI type. what is the problem?
router(config)#interface serial 0/0
router(config-if)#frame-relay lmi-type cisco
% Unrecognized command
router(config-if)#frame-relay ?
% Unrecognized command
A. The interface does not support frame Relay connections.
B. The interface does not have an ip address assigned to it yet.
C. the interface requiers that the no shutdown command be configured first.
D. The interface requires that the encapsulation frame-relay command be configured first.
the answer on the dump is D. but i think A is correct. Because when i enter the command: “router(config-if)#frame-relay lmi-type cisco” before entering “router(config-if)# encapsulation frame-relay” it says “Must set encapsulation to FrameRelay before using FrameRelay subcommands”
check out the output below
Router(config-if)#
Router(config-if)#frame-relay lmi-type ?
ansi
cisco
q933a
Router(config-if)#frame-relay lmi-type cisco
Must set encapsulation to FrameRelay before using FrameRelay subcommands
Router(config-if)#frame-relay ?
interface-dlci Define a DLCI on an interface/subinterface
lmi-type Use CISCO-ANSI-CCITT type LMI
map Map a protocol address to a DLCI address
i think the answer of q7 is d : incorrect ip add
to examtaker the answer is d because we must determine the kind of encapsulation first (fr) afterthat we determine the type of lmi .
In Q7, they don’t give us the mask info, nor the “show frame-relay map” for RouterB.
If the mask is 255.255.0.0, Router A and B are on the same network.
The problem can be an incorrect map statement on Router B. RouterA can reach RouterB, but without a correct map statement on RouterB, the reply can’t make the way back.
So I guess is answer C
why answer is B ?? why not C ?
http://class10e.com/Cisco/in-the-frame-relay-network-which-ip-address-would-be-assigned-to-the-interfaces-with-point-to-point-pvcs/
q7 in today exam
I am going to take the ICND1 but i am little bit confused. Because i see on the rights side of this page only CCNA question. So which do i have to learn and which are for incd2?
Can anyone give me some info
thanks
hello all (cisco engineers)
soon joining the club after my certification on 23 jUNE
Can anyone elaborate on that.
The answer is good but explonation not at all.
IP address and DLCI number is right – but problem is on router B – just wrong mapping.
Wen u check d graphics, d address of next router is 4 router B but d DLCI is 50 wich is for A……DLCI shud b 75 for b in d statement….so I guess “incorrect map statement” c is d right answer….
Please please please guys i am preparing for the exam next month, can someone be kind enough to send me the latest dumps on my e-mail : mastermalganis@hotmail.com
on the exam tomorrow!
Pliz i will sit for the exam next month, can someone send me the latest dumps on email: olesimbe@yahoo.com
Q7 explanation http://www.aiotestking.com/cisco/2012/04/what-is-the-most-likely-cause-of-the-problem-5/
answer of q7 is incorrect ip address,incorrect map addressing is wrong ans
So…can anyone once for good explain answer for Q7? Is it C or D? Anyone knows which one for sure and why?
simple!!
the Answer is C, why?
the question didnt specify which 1 is Router A and which is Router B, so that is where the trick is!!
Assume that left Router is Router A, then apply that map statement, you will find that that statement is correct and if you try to ping the ping will reach to the other router and the reply will depend on the config of the that other Router.
Then Again, Assume that the Right router is Router A the you will find that, the map ip statement is incorect and with that statement the ping will never reach to the other Router.
So come to the Question, it state that:-
Router A is unable to reach Router B ….. …….
that means the Right is Router A and from that map statement it can not reach left Router which is Router B.
Q7 on CCNA exam today
Tomorrow ……..
Q: 4
Please, can someone explain the answer to the question number 4?
B. They require a unique subnet within a routing domain. —– Is right
But the other answer is not sure.
http://certificationpath.com/view/640-816-s/questions/what-are-two-characteristics-of-frame-relay-pointtopoint-subinterfacesy-a-composite-solution-q24436
hi my friends, can i study only 9tut to pass the CCNA exams. am taking the exams next month
Today I pass the exam, and I had identical exhibit like Q7, but the question/choices was (as I remember):
How router learn about DLCI:
1 ARP
2 proxy ARP
3* Inverse ARP
4 something like: frame relay inverse map
5 something else…
* – my mark
Regarding Q7. Initially I also said that “D. incorrect IP address” is the correct answer. Then I checked this setup with GNS3.
What surprises me is that if frame-relay map statement is correctly configured in both routers, the ping between them works even if one router has ip address 192.168.1.1 and the other router has ip address 10.1.1.1 (so this means the routers are in totally separate subnets, and there is no router in between, just the frame relay switch).
The configuration is like this:
R1# sho run int s0/0
Building configuration…
Current configuration : 176 bytes
!
interface Serial0/0
ip address 192.168.1.1 255.255.255.0
encapsulation frame-relay IETF
clock rate 2000000
frame-relay map ip 10.1.1.1 50
frame-relay lmi-type ansi
end
R2#sho run int s0/0
Building configuration…
Current configuration : 176 bytes
!
interface Serial0/0
ip address 10.1.1.1 255.255.255.0
encapsulation frame-relay IETF
clock rate 2000000
frame-relay map ip 192.168.1.1 75
frame-relay lmi-type ansi
end
Now try to ping:
R1#ping 10.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/6/12 ms
R1#
R2#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
R2#
Surprise!!! so the ping works even if there is no router to route between the two subnets, but only the frame relay switch. I cannot explain this, however based on this I would now agree that :C. incorrect map statement” is the correct answer.
q6 on exam today
question 7..my answer would be D.the dlci is locally significant and is mapped to the remote ip address which is the address of the next router.router A would reach router B if they were on the same subnet.Router A subnet–> 192.168.1.0 Router B subnet —> 192.168.2.0 .that’s my thought
if question 7 comes up i am answering B
as you map the local dlci to the remote ip
that means that 50 should be mapped to remote ip….which it is ..
plus there is no way to tell if the dlci is local or global…thats why im answering b
Thank you for everthing 9tut!!
I passed my exam 907/1000
VTP Sim, EIGRP and ACL 2
Also, I saw a few question about frame relay I havent seen before – be careful
Q7
guys, it emulates a point to point connection (just like PPP). even if in different subnet, it works because frame relay and PPP works on layer 2 and besides there is no other destination except on the other end. Therefore, frame-relay has no other choice but to send it to the other end.
I hope it’s clear.
q7 it is incorrect ip address oly
q7 it is incorrect ip address oly
hi,
so what is really the correct answer for q7? is it incorrect ip or incorrect map?
thanks.
what is the correct answer for q7?
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Q7, if you look at the question ‘after reviewing the command output and graphic’, it says two exhibits should be there. So we are only given a graphic without command output, I guess we can’t tell which one is correct. I rather think there is one more exhibit in the real exam. If anyone saw this question in real exam, please confirm.
Q7. In troubleshooting: You check the config and eliminate the possible causes.
1. The key I think is in the question. ‘Which is the most ”’likely””’ not necessarily the actual cause and because there’s not enough information we cannot assume what we don’t know except if there’s a pointer.
2. We are looking at the network from Router A end so its does not matter what router B has or does not have we cannot tell. Even the question says so.#
Answer:
Mr Net Admin can see that the DLCI map is correct as he is aware of the IP on the remote side as shown in the question.
Local DLCI (Router –> FR switch) is mapped to remote IP destination.
Thus, IP is correct, DLCI map is OK. irrespective of hub and spoke or 1 – 1 connection. Therefore we are sure of this because we have evidence that its correct.
The question is can the bandwidth or LMI type be the problem.
Bandwidth issues will most likely cause congestion and not loss of connection.
Yes, LMI type can cause problems and is a ””likely”” cause since we don’t have evidence that it’s not we can’t eliminate it.
ANSWER is B.
Beshoy Abd Elmaseh Mekhail
there are a difference between the relation between IP and DLCI
are we configure the static map as { frame-relay map ip (remote ip ) (local DLCI )}
is this right or wrong ?
is this is the same in frame multipoint and point-to-point ?
Mayberry
interface serial 0/0/0
no frame-relay inverse-arp
frame-relay map ip 199.1.1.2 52 broadcast
frame-relay map ip 199.1.1.3 53 broadcast
but in CBT nugets
frame-relay map ip 199.1.1.2 51 broadcast
please someone show me the correct
Q 7 Ans is C. incorrect map statement
Thanks 9tut. I made it. I passed my CCNA 200-120 today. The sim is Access-list 1 , Access-list 2 & EIGRP. A lot of new questions like Netflow, Syslog, SNMP, VRRP, and GLBP.
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Has anyone passed exam with 1000/1000 score,and q7 was in exam?)
if there is such person please say what u marked in exam for q7))
Every one go to 9tut.com for ccna
Q7 did indeed have a second graphic showing the actual map statement, which had the remote DLCI tied to the remote IP – which is not correct. Ergo, C
answer d) incorrect ip address 192.168.1.1 to 192.168.2.2 are in diferent subnet
Yea I know Q7 is confusing, I looked at most of the posts, i don’t know why they overcomplicated something simple . When I look at the map statement it’s incomplete, you need two statement to get the full connection and i think that’s what they mean by incorrect statement. As for the IP address we don’t know that mask so we can’t say for sure, even though it would be more logical. Hope this helps, I’m going for the test this week, second try, can anyone please email me the latest dumps thanks mahadali@yahoo.com
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