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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
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  1. bodo1111
    July 24th, 2019

    Passed today with 840. I had OSPF sim. The topology and the questions are the same. I am unsure about question 1. R4 is the asbr but in the ospf topilogy there is not any lsa4 advertised. Sh ip ospf and sh ip ospf database commands are available. No additional ip ospf database comm are available like routers, summary or asbr-summary.

  2. Anonymous
    July 24th, 2019

    @bodo1111 congratulation dude, you meant ospf sim or ospf evaluation sim ?

  3. SpeerGag
    July 25th, 2019

    I passed the switch exam yesterday, now studying for 300-101 Route, can anyone please send me the valid dumps to mikeuthoff @ Yahoo . com Thanks in advance

  4. Don.Raj
    July 26th, 2019

    Hi All,
    I am planning to write exam in Aug 10. Can some one please send me the latest dumps to my email id. victory . karthi8 @ gmail. com

  5. meenal
    July 27th, 2019

    hello everyone.

    which lab is coming in exam? do i prepare all lab given the pdf?

  6. Mike Scofield
    July 29th, 2019

    Hi SpeerGag,

    I congraats on your switch exam, I have mailed you the valid dumps, i nalied my route exams yesterdays.check your mail.

    -Mike

  7. ManicSheep
    July 30th, 2019

    Mike, are you able to send me a copy as well brother?

  8. Armand walace
    July 30th, 2019

    just passed my 300-101 today and i had this lab on my exam. all the answers here are good but i notice something strange, when you run the sh ip int S1/1 on R3, it displays that that network type on that link is point to point and the timers displayed on that link R1-R3 are 10;40;40 which match with Answer C. but i advise you to step on Answer B as mentioned. that is what i choosed.

  9. tanya
    July 31st, 2019

    hie Armand. what other labs were in the exam?

  10. Janekurr
    July 31st, 2019

    Hi,
    Would you send me the latest dump please. Google account janekurr1995
    Huge thanks in advance

  11. Anonymous
    July 31st, 2019

    Hi,
    Would you send me the latest dump please. janekurr1995 @ gmail . com
    Huge thanks in advance

  12. Blue Thunder
    August 6th, 2019

    Hi Mike,
    Would you send me the latest dump as well brother?
    {email not allowed}

  13. Blue Thunder
    August 6th, 2019

    Hi Mike,
    Would you send me the latest dump as well brother?
    bluethunder1414 @ gmail . com

  14. drazo
    August 7th, 2019

    Hi Mike,
    Would you send me the latest dump as well drazenmd @ blic . net

  15. Anonymous
    August 7th, 2019

    Hi mike !!

    Would you send me the latest dump as well brother?

    {email not allowed}

  16. Raul
    August 7th, 2019

    Hi mike !!

    Would you send me the latest dump as well brother?

    rauledmundo @ hotmail . net

  17. Raul
    August 7th, 2019

    Hi mike !!

    Would you send me the latest dump as well brother? the first email address is wrong . Send to this please

    rauledmundo @ hotmail . com

  18. Ashosho
    August 10th, 2019

    Hi All,

    Can someone pls email me the valid dump at mirabela2000ng @ yahoo .com
    Thanks

  19. Q1 Again
    August 17th, 2019

    I am trying to understand ira’s point.
    The ASBR-SUMMARY, LSA type 4 for area 1 is in R4
    (On R4 do show ip ospf database, and it is link id 4.4.4.4 advertised by R3.)

    So on R5 Summary Net Link, it is coming from the 4.4.4.4 link ID (not 3.3.3.3) that has the correct age time.

    Gosh, can someone explain it better? Please?

  20. Curious
    August 23rd, 2019

    Can anyone as to why we should use use GNS3 with version older than v1.0 to open this OSPF Sim??? (v0.8.3.1 for example).

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