Lab 3 Task 4.4


On this particular Lab and task (Lab 3 Task 4.4), there is no area 0 to configure. The area that all other areas are connected to is area 135.
I configured this but then I put in "show ip ospf | begin BACKBONE" command and as I thought it would say, it showed that the backbone was inactive.
From my understanding, the backbone has to be Area 0 as all LSA 3's/5's traverse this area to other areas so the ABR's can learn about other networks.
I changed the area 135 to area 0 and could get everything working. Could someone explain how area 135 (or any other area except 0) can be used as the backbone as I haven't seen anywhere before that this can be done.
Many tks,



  • I had the same problem, not sure how IE managed to make their config work as per the solution.

    To solve the problem of area 0 beeing inactive I have created a loopback 100 interface on R5 with net and associated it with area 0.

    All came up after this

  • I have the same problem.

    By the way, between R3 and R1 if we make ospf interface priority to 0 for task 4.4, neighbor command disappears on R3 and R1 for each other respectively. (ospf Network Type NON_BROADCAST)

    In this case solution in IExpert soution guide 'area 135 virtual-link' on R3 and 'area 135 virtual-link' on R1, how this v-link would work when ospf neighbor is not established between R1 and R3.
  • have a look at the following discussion:
    archive link
    this problem exists for such a long time with no Comment/explaination From IE.i am wondering if we would ever get any.
    i guess we can solve it by configuring LO 0 of R3 in area 0,as task4.8 does not specifically say which area it should be in.
  • Thanks JanZ, Well that would definitely work but that breaks the requirement of task 4.8 and lo0 network of R3 will show up in R1 as of /32 network since that is in area 0 when we use ‘area range’ command since we can’t use ‘ip ospf network point-to-point’ command. To overcome this situation I created another loopback interface on R3 and advertise in area 0, now I don’t know in real lab if we would be allowed to create another loopback interface.

    But , thank you for response.

    I still wonder if OSPF works without Area 0 in multiple areas? I wish Brian & Brian answer this question.
  • yes you are right,got stuck there myself while configuring task 4.8,some help/hint would certainly be appriciated by any one from IE.
  • Hi,
    Here is my configuration:
    interface Loopback0
    ip address
    ip ospf 1 area 0
    router ospf 1
    area 0 range
    I don't think that we can create extra loopback interfaces.
    Additionally, area 0 is mandatory in case of a multiple area OSPF environment.

  •  Originally Posted By: Fabou

    I have created a loopback 100 interface on R5 with net and associated it with area 0.

    Hi Fabou,
    You should read Do's and Don'ts before do anything: "Do not change or add any IP address""
    I think, your solution is no accepted.

  • I think the whole 4.5 "thang" is just nasty.

  • Hi,

    there is no other solution than adding area 0, because ospf needs area 0 as a backbone area. I added loopback1 with for area 0 to let the virtual link come up.

  • In task 4.8 it is mentioned that R3 Lo0 to be associated to any area so it is better to assign that only to area0 and use area0 range command there> also SG itself creates Virtual Links from R1 to R3 so it should be R3'Lo0 in Area0
  • The answers to your questions is in the Quick note, page 66 of SG.

    (bullet 1 of task 4.6 had been configured in task 4.5 to get the verification ouput)
  • Hello,

    sorry , buT I can't see what is the problem here ?

    in task 4.6 he advised to c onfigure loopback 0 on R1 in area 0 , so we have area 0 here

    I have tested it and it is working without Area 0 on the R3

    the DOC CD stated that the 2 routers should be ABR ( that does not mean they are connecting to area 0) , but it means that they are connecting between 2 areas

    May I miss something here , please advise

    also check the link for some examples

    thanks & BR
  • Hi,
    I know this is a REALLY old posting, but I just did this lab today and it worked for me no problems. The virtual link came up just fine, but then I configured the virtual link after I put Loopback0 of R1 into Area0, as stated in Task4.6, which means Area0 existed when I configured it so maybe that's why I had no issues.

    Also, in that archive posting mentioned earlier it says that you are not to use the interface network statement, but that is OK for R1 as it just says not to use the network statement for the task concerning R3; a completely different task!!!

    When these workbooks say to not use a command it only applies to that task, as all the way through the workbooks it tell you not to use a command here, but you must use it in another place!
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