CCNA EIGRP LAB Question
Question
After adding R3 router, no routing updates are being exchanged between R3 and the new location. All other inter connectivity and Internet access for the existing locations of the company are working properly.
The task is to identify the fault(s) and correct the router configuration to provide full connectivity between the routers.
Access to the router CLI can be gained by clicking on the appropriate host. All passwords on all routers are cisco.
IP addresses are listed in the chart below.
| R1 Fa0/0: 192.168.77.33 S1/0: 198.0.18.6 S0/1: 192.168.60.25 S0/0: 192.168.36.13 |
R2 Fa0/0: 192.168.60.97 Fa0/1: 192.168.60.113 S0/0: 192.168.36.14 |
| R3 Fa0/0: 192.168.77.34 Fa0/1: 192.168.60.65 Fa1/0: 192.168.60.81 |
R4 Fa0/0: 192.168.60.129 Fa0/1: 192.168.60.145 S0/1: 192.168.60.26 |
Answer and explanation
(Note: If you are not sure how EIGRP works, please read my EIGRP tutorial: http://www.9tut.com/eigrp-routing-protocol-tutorial. Note: You can download this sim to practice here: http://www.9tut.com/download/9tut.com_CCNA_EIGRP_sim_question.zip)
We should check the configuration of the new added router first because it does not function properly while others work well. From the command line interface of R3 router, enter the show running-config command
From the output above, we know that this router was wrongly configured with an autonomous number (AS) of 22. When the AS numbers among routers are mismatched, no adjacency is formed.
(You should check the AS numbers on other routers for sure)
To solve this problem, we simply re-configure router R3 with the following commands:
R3>enable (you have to enter cisco as its password here)
R3#configure terminal
R3(config)#no router eigrp 22
R3(config)#router eigrp 212
R3(config-router)#network 192.168.60.0
R3(config-router)#network 192.168.77.0
R3(config-router)#no auto-summary
R3(config-router)#end
R3#copy running-config startup-config
Check R1 router with the show running-config command:
Notice that it is missing a definition to the network R3. Therefore we have to add it so that it can recognize R3 router
R1>enable (you have to enter cisco as its password here)
R1#configure terminal
R1(config)#router eigrp 212
R1(config-router)#network 192.168.77.0
R1(config-router)#end
R1#copy running-config startup-config
Now the whole network will work well. You should check again with ping command from router R3 to other routers!
Modifications:
Maybe in this EIGRP Sim you will see the “passive-interface …” command somewhere in R1 configuration. If the link between R1 to R2; or R1 to R3; or R1 to R4) routers has the “passive interface” then we have to remove it with the “no passive-interface …” command because it prevents EIGRP update from being sent on that interface. But if the “passive interface” is applied to the link between R1 and ISP router like this:
R1:
!
router eigrp 212
passive-interface s1/0
!
then we just leave it. Don’t use the “no passive-interface s1/0″ on R1 because the link between R1 & ISP doesn’t need EIGRP to run on it. A static route from R1 to ISP & “ip default-network” command in R1 are correct so that all the routers (R1, R2, R3, R4) can access the Internet.
(Note: The “ip default-network” command in R1 will advertise the static route of R1 (to go to the Internet) to other routers (R2,R3,R4) so that they can access the Internet too). In the exam you will see these lines in R1 configuration:
!
ip default-network 198.0.18.0
ip route 0.0.0.0 0.0.0.0 198.0.18.5
!
If you want to learn more about “ip default-network” command please read: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml
I read recent comments and realized that you will see the “passive-interface” in the link between R1 & ISP router so just leave it.
Note: Also some readers confuse about if we should use the wildcard masks on the “network” statements under EIGRP process or not. For example should we use:
router eigrp 212
network 192.168.77.0 0.0.0.3
The answer is: we can use wildcard masks or not, it does not matter. Not having a wildcard mask does not make the routes conflicting. The “network …” command in EIGRP (and OSPF, RIP) does not means “advertise this network” but means “If I has interface(s) belongs to this network please turn on EIGRP on that interface. Therefore when you don’t use wildcard mask EIGRP will turn on EIGRP on all interfaces that belongs to the network you specify in the “network …” command.
You should only use wildcard mask on EIGRP if you have 2 or more interfaces that belong to the same major networks but you don’t want to run EIGRP on all of them. For example if your router has 2 interfaces whose IP addresses are 192.168.30.1/28 and 192.168.30.17/28 but you only want to run EIGRP on the first interface, you can type “network 192.168.30.0 0.0.0.15″ under EIGRP process.
Other lab-sims on this site:
CCNA Configuration SIM Question (RIPv2 SIM)
when these networks are advertised under eigrp 212 should they have a mask after them as they are classles networks ????????
EIGRP uses classless routing, which means that the subnet mask information is sent along with routing protocol updates but you don’t need to add a mask after them
how do i open the sims in packet tracer…please help
fde
1) whats the purpose of writing ” R3(config-router)#no auto-summary” this command, whats the explanation of this ?
2) Kindly write ping command on R3 to check R1?
what is the explanation of the command ( R1#copy running-config startup-config ) and also the command ( R3(config-router)#no auto-summary ) plzzzzzzzzzzzzzzzzzz
no auto-summary gets rid of problems when router adds 24 bit mask by default to any address you enter in configuration. to use custom masks like /30 you need to set no auto-summary
copy running-config startup-config – saves current configuration file
hi ,
i am going to give ccna exam on 27 of this month.
testinside acme and labs of 9tut only , if i perepare it is sufficent to pass the exam.
please reply ………..
and also please say , where ip nos will be chainged for this questions , during exam
i am not taking about lab, i am talking about theory questions.
Kindly write ping command on R3 to check R1?
no ping command is not enough !!! it will ping R1 but you need to make sure R1 show run shows eigrp 212 network 192.168.77.0
Guys, in the real eigrp sim exam.. .there’s extra network address. i think they are 5 network it’s under router 1 something like below…. .it won’t affect the connection… but do we need to remove it there? or leave it as it is?.
router eigrp 212
x.x.x.x
c.c.c.c
z.z.z.z
v.v.v.v
b.b.b.b
@ Mohamed Emad
You can use auto-summarization with /30 or other masks. Anonymous’ explanation of disabling auto-sum for only being able to use masks like /30 is not correct.
Suppose you have different networks attached to a router. By default routing protocols will not send all these networks in its routing update. Instead to save bandwidth and to keep the routing table of target router smaller, all routing protocols summarize routes at major class boundaries for networks belonging to one class.
To see examples, check the summary route questions mentioned in I guess subnetting or operations sections of 9tut.com.
While it’s a great feature sometimes we have to turn it off with no auto-summary command to avoid problems. For example if R1 is connected to R2 on fa0/2 and to R3 on fa0/3 and you are using same class networks say 172.16.x.x on R2 and R3 with whatever masks. It is quite possible that you have an addressing scheme for which when R3 and R2 summarize the networks, the summary route is the same and they both send it to R1.
Now R1 will see the same summary route coming on it’s 2 different interfaces and will have no way of telling that they are different routers. It might think that it’s in 1 network it has learned on different interfaces and might start to try load balancing on fa0/2 and fa0/3 connections.
No if some traffic arrives on R1 from some R0 for a host on R2, and some traffic arrives for a host on R3, what will happen? R1 will exit half the packets from fa0/2 and half the packets from fa0/3. No single host will get the complete traffic destined to it from R0, and R2 and R3 will keep delivering the packets that match the routes while discarding the traffic that doesn’t match.
It would be a must to issue no auto-summary command on R2 and R3 if you have same class networks on both of them.
@ Mohamed Emad
My above post , Para 2: Suppose you have…
Correction: Not all protocols auto-summarize. AS FAR AS I KNOW RIPv2 and EIGRP auto-summarize.
Hi guys. I am used to add the network statments for eigrp with wilcardmask also (ex: network 192.168.77.32 0.0.0.3). Is it wrong to do so at the ccna lab? will i get full points if i do the lab this way?
Hi all, i take the ccna exam in a few days, does anyone have the sim for this?
rob_jones1221@hotmail.com
cheers people
9tut, regarding my post.. .do you have any idea?
@tony: In real life, you should remove it but in the exam just leave it as it is.
@ Decher
Try to stick to the syntax of the command. It’s a great thing if you’ve run into the habit of using wildcard masks. It’ll do you no harm in the lab except a slight miscalculation can ruin your configuration and in exams you’ve to be very accurate the 1st time. There are already a lot of troubleshooting questions and you wont want start troubleshooting your own SIM. Would you?
Cheers
hello,
i got packt tracer sim. i tryied with eigrp. its working fine bt m unable to ping 192.0.18.4 from R3. bt abl to do from R1.
plz reply back ..
Thanks a lot for the reply. I will go take my ccna exam in 16 december. I will post again to tell you what labs/theory question i had.
hey people, as i belive the sims will be acl 2, eigrp and vtp, can anyone confirm if this is still true?
HI BROTHERS PLEASE WHO CAN TELL ME THE autonomous SAME THE PROCESS ID OR NOT I AM WAITING THE ANSWER THANKS
@ tamem: In exams the AS number these days is 22 and on the wrong configured router its 23 so you have to correct it.
thanks Aamir
I had my exam on the following sims from 9tut.com
EIGRP sim the one on this page
Access list sim similar to the one on 9tut
swithing vtp also on 9tute
do all this question on 9tut LAB SIM on’s and understand and analyse the question carefully
do pass4shure about 250 questions
You will do more than a PASS.
I had
Thankyou
for helping me pass ccna
http://www.9tut.com
Mery chrismas to everybody here.
how to check which route to be deleted on R1 router of eigrp sim ???
Hi everyone,
pls, can i get a link like 9tut,for those in juniper networks. i want to write my jncia er next week.9tut thanks for what you are doing for ccna candidates.pls,need a quick response
hello
i want to ask if i configure each part on its own pc
ie the configuration part concerning router3 should be configured on host d
and the one concerning router1 on host g
thank you
How about split horizen, how do we deal with it on this senerio?
(N/W 2 INFO) R1 R2 (N/W 1 INFO)
Stylus,
(N/W 2 INFO) R1 R2 (N/W 1 INFO)
Stylus,
R1 and R2 will share their diractly connected n/w, But they will not revert the n/w info wher you learned. Ex. R1 will not update n/w 1 info back in to (R1 s/0) where it learned.
got this 2day .. with slight difference (22 , 221 ) , thxxx 9tut
can someone please explain where we got these to addresses from:
R3(config-router)#network 192.168.60.0
R3(config-router)#network 192.168.77.0
Thanks
@teeka, which dumps did you study and which sims were on your exam plz. Was questions the same?
So nervous for write cisco exAM!
9tut
Why are there no wildcard masks after the network commands ?
I’m confused, surely following this exact example we’ll drop marks ??
We don’t need to use wildcard mask when it’s in the major network. For example the 2 commands below are the same:
network 192.168.60.0 is same as
network 192.168.60.0 0.0.0.255
can anyone explain why there is the command no auto-summary on router 3 but not on router 1
I’m about to take my exam at 3pm West African time. Please 9tut give me an answer
If I do
network 192.168.60.0 0.0.0.255
network 192.168.77.0 0.0.0.255
no-auto-summary
OR
network 192.168.0.0 0.0.255.255
no-auto-summary
they do the same thing. and both give the same result and routing info in R1.
In the exam , does it matter which way I’m doing it ???
will I get the full marks either way ??
please reply !!
Thanks.
@mark: R1 has the “no auto-summary” command too but we don’t need to type it again because we don’t create a new AS in R1 and this command exists in the current AS. In R3, we need to create a new AS 212 to replace AS 22 so we need to add “no auto-summary” command.
@Shamal: Both your configurations are correct in real life but in the exam you have to do on a simulator (with programmed answers) so my recommendation is “never try anything you are not sure”. Always do the sims in the best & clearest way!
thanks 9tut.
Hello the rumor at examcollection website is that mashti and acme no longer valid anyone know if true?
Can anyone tell me which ip i’ve to ping from R3..aft i have done the above changes..??
shouldn’t the network statements be the actual subnet address? for example 192.168.77.34 255.255.255.252 should be network 192.168.77.32. Why is it 192.168.77.0 in this configuration?
Nevermind, it’s because of no auto-summary. I didn’t see that there…
Hi mates, i was fail yesterday only score 815 out 1000. there are many quetions’ been changed.just be carefull with simulation questions, its very hard but the multi answer question, i think its no to hard. i had only 3 sim questions, i only have 1 right but still fail. so just be carefull with sim question. im gonna reseat again in a week time. best of luck to all of u.
Hi guys, just finish my exam now and it was so cool, scored 949 sims are eigrp, access list, vtp but made a mistake with vtp, i only did 1 questn and click next.
Thank God, thank u guys, thank 9tut re d best.
@Curios
can you please confirm that there are no change in the mashti or acme dump?
Thx