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OSPF Evaluation Sim

February 9th, 2015 in Lab Sim Go to comments

You have been asked to evaluate an OSPF network and to answer questions a customer has about its operation. Note: You are not allowed to use the show running-config command.

OSPF.jpg

Although in this sim we are not allowed to use “show running-config” command but we post the configuration here so that you can understand more about the topology.

R1
interface Loopback0
ip address 1.1.1.1 255.255.255.255
!
interface Serial0/0
ip address 192.168.13.1 255.255.255.0
ip ospf network non-broadcast
no shut
!
router ospf 1
network 192.168.13.0 0.0.0.255 area 0
network 1.1.1.1 0.0.0.0 area 0
R2
interface Loopback 0
ip address 2.2.2.2 255.255.255.255
!
interface S0/0
ip address 192.168.23.2 255.255.255.0
ip ospf network non-broadcast
no shut
!
router ospf 1
network 192.168.23.0 0.0.0.255 area 0
network 2.2.2.2 0.0.0.0 area 0
neighbor 192.168.23.3
R3
interface Loopback 0
ip address 3.3.3.3 255.255.255.255
!
interface Ethernet0/0
ip address 192.168.34.3 255.255.255.0
no shut
!
interface S1/0
ip address 192.168.23.3 255.255.255.0
ip ospf network non-broadcast
no shut
!
interface S1/1
ip address 192.168.13.3 255.255.255.0
ip ospf network non-broadcast
no shut
!
router ospf 1
network 192.168.13.0 0.0.0.255 area 0
network 192.168.23.0 0.0.0.255 area 0
network 192.168.34.0 0.0.0.255 area 1
network 3.3.3.3 0.0.0.0 area 0
area 1 virtual-link 4.4.4.4
neighbor 192.168.23.2
R4
interface Loopback 0
ip address 4.4.4.4 255.255.255.255
interface Ethernet0/0
ip address 192.168.34.4 255.255.255.0
no shut
!
interface Ethernet0/1
ip address 192.168.45.4 255.255.255.0
no shut
!
interface Ethernet0/2
ip address 192.168.46.4 255.255.255.0
no shut
!
router ospf 1
network 192.168.34.0 0.0.0.255 area 1
network 192.168.45.0 0.0.0.255 area 2
network 192.168.46.0 0.0.0.255 area 3
network 4.4.4.4 0.0.0.0 area 1
area 1 virtual-link 3.3.3.3
area 2 nssa
area 3 stub no-summary
R5
interface Loopback0
ip address 5.5.5.5 255.255.255.255
interface Loopback1
ip address 5.5.1.1 255.255.255.255
interface Loopback2
ip address 5.5.2.1 255.255.255.255
interface Loopback3
ip address 5.5.3.1 255.255.255.255
interface Loopback4
ip address 5.5.4.1 255.255.255.255
interface Ethernet0/0
ip address 192.168.45.5 255.255.255.0
no shut
!
router ospf 1
network 192.168.45.0 0.0.0.255 area 2
network 5.5.0.0 0.0.255.255 area 2
area 2 nssa
R6
interface Ethernet0/0
ip address 192.168.46.6 255.255.255.0
no shut
interface Loopback 0
ip address 6.6.6.6 255.255.255.255
!
router ospf 1
network 192.168.46.0 0.0.0.255 area 3
network 6.6.6.6 0.0.0.0 area 3
area 3 stub

Some notices from above configuration:

+ The OSPF network type between R2 & R3 is non broadcast.
+ R3 and R4 is running virtual-link to connect Area 2 & 3 to Area 0
+ Area 2 is a NSSA area while Area 3 is a Totally Stubby area

You can download this sim to practice at http://www.digitaltut.com/download/ROUTE_OSPF.zip. Please use GNS3 with version older than v1.0 to open it (v0.8.3.1 for example). IOS used in this lab: c3640-jk9s-mz.124-16.bin

Question 1

Explanation

To check OSPF LSA we should use the “show ip ospf database” command on R5:

R5_show_ip_ospf_database.jpg

In this sim there is no LSA Type 4 because there is no ASBR so maybe this question wants to ask about LSA Type 3 (Summary Net Link States).

Note: LSA Type 4 is generated by ABR, not ASBR but without ASBR inside the network there are no LSA Type 4 generated. For more information about OSPF LSA Types please read our OSPF LSA Types Lab tutorial.

R3 advertises LSA Type 1 to R4 then R4 converts it into Type 3 and sends to R5 (because R4 is the ABR) so we see the “Link ID” 3.3.3.3 of R3 is advertising by R4 (4.4.4.4). According to the “Age” column, this LSA was advertised 1858 seconds ago.

Question 2

Explanation

Check the Serial1/0 interface of R3 which is connected to R2 with the “show ip ospf interface serial 1/0” command:

R3_show_ip_ospf_interface_serial.jpg

There are two things we should notice from the output above:
+ The “network type” connection between R2-R3 is “NON_BROADCAST” (usually we have “BROADCAST”). OSPF neighbors are discovered using multicast Hello packets. In non broadcast environment, multicast (and broadcast) messages are not allowed so OSPF neighborship cannot be formed automatically. Therefore we have to establish OSPF neighborship manually by using “neighbor ” command under OSPF process (OSPF will send unicast Hello message to this address). For example on R2 we have to use these commands:

router ospf 1
neighbor 192.168.23.3

And on R3:

router ospf 1
neighbor 192.168.23.2

+ For non broadcast environment the default Hello timer is 30 seconds; Dead timer (time to wait before declaring a neighbor dead) is 120 seconds and Wait timer (causes the interface to exit out of the wait period and select a DR on a broadcast network. This timer is always equal to the dead timer interval) is 120 seconds. In the output we also see the default timers for non broadcast network.

Question 3

Explanation

We can check the number of executed SPF algorithm via the “show ip ospf” command on R4:

R4_show_ip_ospf.jpg

In the output above we can see SPF has been executed 9 times.

Question 4

Explanation

Area 2 (of R5) is a Not-so-Stubby area (NSSA). You can check it by the “show ip ospf” command on R4 or R5 (in Area 2 section). For example, below is the output of “show ip ospf” command on R5:

R5_show_ip_ospf.jpg

In general, NSSA is same as normal area except that it can generate LSA Type 7 (redistribute from another domain) so we can see both Loopback interfaces of R5 & R6 in the routing table of R5.

R5_show_ip_route.jpg

Note: NSSA does not receive a default route by default so you will not see a default route on R5.

Area 3 (of R6) is a Totally-Stubby area so R6 only has one default route to outside world. You can check with the “show ip ospf” command on R4 and R6 (area 3 section):

R4_show_ip_ospf_area3.jpg

R6_show_ip_ospf.jpg

Notice that on R4 you will get more detail (shows “stub area, no summary LSA”) than on R6 (only shows “stub area”).

R6 is in a totally-stubby area so we will not see any R5’s Loopback interfaces in R6 routing table:

R6_show_ip_route.jpg

Note: You can see a default (summary) route to the outside (O*IA 0.0.0.0/0 …)

Comments
Comment pages
1 9 10 11 1016
  1. CCNP W
    March 10th, 2017

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  2. Need help
    March 13th, 2017

    My CCNA expires in few weeks.
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  3. QuestionMan
    March 14th, 2017

    thx but about Qusetion 1

    i think..

    R1
    router ospf 1
    network 192.168.13.0 0.0.0.255 area 0
    network 1.1.1.1 0.0.0.0 area 0
    + “neighbor 192.168.13.3”

    R3
    router ospf 1
    – omitted config –
    neighbor 192.168.23.2
    + “neighbor 192.168.13.1”

    when i end this config, result is Question 1’s image.
    but if Existing config, Question 1’s image is something wrong

    1.1.1.1&2.2.2.2 losted in R5’s ospf database.

    Am i have something mistake?
    thx

  4. QuestionMan
    March 14th, 2017

    R1#traceroute 5.5.5.5

    Type escape sequence to abort.
    Tracing the route to 5.5.5.5

    1 * * *
    2 * * *
    3 * * *
    4 * * *
    5

    —————————————————————————–
    R2#traceroute 5.5.5.5

    Type escape sequence to abort.
    Tracing the route to 5.5.5.5

    1 192.168.23.3 8 msec 16 msec 20 msec
    2 192.168.34.4 36 msec 36 msec 40 msec
    3 192.168.45.5 48 msec * 44 msec

  5. myanmar.jack
    March 18th, 2017

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  6. myanmar.jack
    March 18th, 2017

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    March 18th, 2017

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    March 18th, 2017

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  9. kitten
    March 18th, 2017

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  10. kitten
    March 18th, 2017

    i’m sorry not ikanamikaze but ikaonamikaze

  11. Anonymous
    March 18th, 2017

    JANE woken
    I did get this OSPF evaluation sim in my exam, and I got confused about the answer. I checked the config, where timer values 30, 120, 120 were assigned to link between R1 and R3. So I did not know the answer. The situation made me very confuse. Could somebody tell me the right answer please according the new change?????
    Which of the following statements is true about the serial links that terminate in R3?
    A. The R1-R3 link needs the neighbor command for the adjacency to stay up
    B. The R2-R3 link OSPF timer values are 30, 120, 120
    C. The R1-R3 link OSPF timer values should be 10,40,40
    D. R3 is responsible for flooding LSUs to all the routers on the network.

    r1-r3 should have been 30/120/120/ its non broadcast
    The R1-R3 link OSPF timer values should be 10,40,40=not true
    now if the r2-r3 should show 10.40.40 to make p2p or broadcast to make this question false

  12. CCNP 300-101
    March 19th, 2017

    In 300-101 there is no sort of questions based on Drag & Drop in china
    I have passed it!

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    2.EIGRP-OSPF REDISTRIBUTION
    3.IPV6
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    Don’t forget to ping after the configurations because ping testing holds 15 points in SIM.

    Few New questions from ” Infrastructure Security” Topic and ” Infrastructure Services”.
    please refer any updaed dumps , because 30% of questions belongs to these two topics.

    NOTE: Please be careful when you memorize the answers from Dumps or any PDF , because in the real exam its totally in different order from the Dumps.

  13. alim2017
    March 19th, 2017

    hi CCNP 300-101,congratulation
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    please tell me i’m writting my exam tomorrow

  14. alim2017
    March 19th, 2017

    please CCNP 300-101,tell me if 149q+41q+19 is still valid or not
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  15. Skip
    March 20th, 2017

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  16. alim2017
    March 21st, 2017

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  17. san 2017
    March 22nd, 2017

    Hi Team,

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  18. jZ
    March 23rd, 2017

    Hi San 2017,

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  19. san 2017
    March 23rd, 2017

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    March 23rd, 2017

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    March 24th, 2017

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    March 24th, 2017

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  26. Vasia
    March 27th, 2017

    Today pass exam. Many questions from last.

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  27. o3
    March 27th, 2017

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  28. Pass
    March 27th, 2017

    Just passed with 934 points and 149q+41q+15q still good.
    show ip ospf database does not allowed to execute, don’t know why.
    R2-R3 timers is 10,40,40 and R1-R3 is 30,120,120 (both are different than answer) so the correct ans is A.

  29. Pass
    March 27th, 2017

    I meant the show ip osfp topology cannot execute?

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