Task 4.5 (OSPF area range)

Hello.

I did the configuration below:

R3:

router ospf 1
 log-adjacency-changes
 area 0 authentication message-digest
 area 123 virtual-link 150.25.1.1 message-digest-key 1 md5 CISCO
 network 145.25.3.3 0.0.0.0 area 0
 network 145.25.13.3 0.0.0.0 area 123
 network 145.25.23.3 0.0.0.0 area 123
 network 150.25.3.3 0.0.0.0 area 0

R5

router ospf 1
 log-adjacency-changes
 area 0 authentication message-digest
 area 25 range 150.25.0.0 255.255.240.0
 area 25 virtual-link 150.25.8.8 message-digest-key 1 md5 CISCO
 area 125 virtual-link 150.25.1.1 message-digest-key 1 md5 CISCO
 network 145.25.5.5 0.0.0.0 area 25
 network 145.25.58.5 0.0.0.0 area 25
 network 145.25.125.5 0.0.0.0 area 125
 network 150.25.5.5 0.0.0.0 area 25

sw2

router ospf 1
 log-adjacency-changes
 area 0 authentication message-digest
 area 25 range 150.25.0.0 255.255.240.0
 area 25 virtual-link 150.25.5.5 message-digest-key 1 md5 CISCO
 network 145.25.48.8 0.0.0.0 area 0
 network 145.25.58.8 0.0.0.0 area 25
 network 150.25.8.8 0.0.0.0 area 25

 

but ,I see R4`s routing table like this

    150.25.0.0/16 is variably subnetted, 6 subnets, 2 masks
O       150.25.7.0/24 [110/68] via 145.25.48.8, 00:00:05, FastEthernet0/1
C       150.25.4.0/24 is directly connected, Loopback0
O       150.25.3.0/24 [110/131] via 145.25.48.8, 00:00:05, FastEthernet0/1
O       150.25.2.0/24 [110/195] via 145.25.48.8, 00:00:05, FastEthernet0/1
O       150.25.1.0/24 [110/67] via 145.25.48.8, 00:00:05, FastEthernet0/1
O IA    150.25.0.0/20 [110/2] via 145.25.48.8, 00:00:05, FastEthernet0/1

How can R4 see R3and R5 `s  loopback0 as a single route ?

 

 

 

 

Comments

  • Hi,

    I have got the same question...How can R4 see R3 and R5's Loopback0 as a single route?



    I think that it is incorrect questions in Mock.:



    They should ask for SW2 and R5's interface Loopback0 network as a single route.



    4.5. OSPF


    • Advertise the Loopback0 interfaces of R1, R2, R3, R4, R5, SW1 and SW2 into OSPF.

    • R4 should see R3 and R5's interface Loopback0 networks as a single route.




    SG:

     R1:

     router ospf 1

     network 150.1.1.1 0.0.0.0 area 0



     R2:

     router ospf 1

     network 150.1.2.2 0.0.0.0 area 0



     R3:

     router ospf 1

     network 150.1.3.3 0.0.0.0 area 0



     R4:

     router ospf 1

     network 150.1.4.4 0.0.0.0 area 0



     R5:

     router ospf 1

     network 150.1.5.5 0.0.0.0 area 25

     area 25 range 150.1.0.0 255.255.240.0




     SW1:

     router ospf 1

     network 150.1.7.7 0.0.0.0 area 0



     SW2:

     router ospf 1

     network 150.1.8.8 0.0.0.0 area 25

     area 25 range 150.1.0.0 255.255.240.0






    My solution was that I advertised R3 and R5's loopback0 into OSPF Area 35. Proctor comment:"R3 and R5's loopbacks are not summarized."
    I did not summarized on R3 and
    R5 (area 35 range 150.X.0.0 255.255.240.0 ), because I would lose reachability to R3 or R5's Loopback0... as per
    virtual-links connections design and Area 35 is "split",
    I think it is not possible to solve this task ( unable to use tunnels
    -Task4.4)...R5 and R3 create summary route 150.X.0.0/20 pointing to Null0...

    Regardless SG, there are summarizing SW2 and R5's
    Loopback0 and because SW2 and R5 are in the same directly connected
    area 25, it is not problem with connectivity, summary route and R4 see
    single route for SW2 and R5's Loopback0
    .



    Any comments..?



    Regards

    Lukas

     

  • It is impossible to do, must be a typo.












  • What's impossible about it?  Where are you looking?

     

    Walk-Thru:

     

    4.5  OSPF

     

    Now it's just a matter of advertising some loopback interfaces! 
    We are not told WHERE to place them though.  So you can pick any area you would
    like.  Area 0 seems to exist just about everyplace!  The one thing to pay
    attention to though is the summarization that we need to do.  In order to have
    those show up as a single router means we'll need to look at an area-range
    command.  In order to do that, we'll need to have the routes in an area OTHER
    than area 0!

     

    R1

     

    router ospf 1

     network 150.1.1.1 0.0.0.0 area 0

     

    R2

     

    router ospf 1

     network 150.1.2.2 0.0.0.0 area 0

     

    R3

     

    router ospf 1

     network 150.1.3.3 0.0.0.0 area 0

     

    R4

     

    router ospf 1

     network 150.1.4.4 0.0.0.0 area 0

     

    R5

     

    router ospf 1

     network 150.1.5.5 0.0.0.0 area 25

     

    SW1

     

    router ospf 1

     network 150.1.7.7 0.0.0.0 area 0

     

    SW2

     

    router ospf 1

     network 150.1.8.8 0.0.0.0 area 25

     

    The good thing is that our two networks to summarize are in a
    single area.  The summarization, we weren't given any requirements about, but I
    would make it as tight as possible!

     

    R5 & SW2

     

    router ospf 1

     area 25 range 150.1.0.0 255.255.240.0

     

    This will technically overlap all of the other loopbacks, but
    most-specific routing always wins!  Unfortunately with the 8.8 networking being
    over a bit boundary, it doesn't make our summarization pretty!

     

    Before:

     

    Rack1R4(config-router)#do sh ip ro os

         51.0.0.0/32 is subnetted, 1 subnets

    O E2    51.51.51.51 [110/20] via 145.1.48.8, 00:00:00,
    FastEthernet0/1

         145.1.0.0/16 is variably subnetted, 13 subnets, 2 masks

    O IA    145.1.17.0/24 [110/67] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA    145.1.23.0/24 [110/194] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O       145.1.3.0/24 [110/131] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O       145.1.7.0/24 [110/68] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA    145.1.12.0/24 [110/130] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA    145.1.13.0/24 [110/130] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA    145.1.58.0/24 [110/2] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA    145.1.125.5/32 [110/2] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA    145.1.125.1/32 [110/66] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA    145.1.125.2/32 [110/66] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

    O IA 192.10.1.0/24 [110/131] via 145.1.48.8, 00:00:20,
    FastEthernet0/1

         150.1.0.0/16 is variably subnetted, 7 subnets, 2 masks

    O IA    150.1.8.8/32 [110/2] via 145.1.48.8, 00:00:06,
    FastEthernet0/1

    O       150.1.7.7/32 [110/68] via 145.1.48.8, 00:00:21,
    FastEthernet0/1

    O IA    150.1.5.5/32 [110/3] via 145.1.48.8, 00:00:21,
    FastEthernet0/1

    O       150.1.3.3/32 [110/131] via 145.1.48.8, 00:00:21,
    FastEthernet0/1

    O       150.1.2.2/32 [110/131] via 145.1.48.8, 00:00:21,
    FastEthernet0/1

    O       150.1.1.1/32 [110/67] via 145.1.48.8, 00:00:21,
    FastEthernet0/1

    Rack1R4(config-router)#

     

    After:

     

    Rack1R4(config-router)#do sh ip ro os      

         51.0.0.0/32 is subnetted, 1 subnets

    O E2    51.51.51.51 [110/20] via 145.1.48.8, 00:00:02,
    FastEthernet0/1

         145.1.0.0/16 is variably subnetted, 13 subnets, 2 masks

    O IA    145.1.17.0/24 [110/67] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA    145.1.23.0/24 [110/194] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O       145.1.3.0/24 [110/131] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O       145.1.7.0/24 [110/68] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA    145.1.12.0/24 [110/130] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA    145.1.13.0/24 [110/130] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA    145.1.58.0/24 [110/2] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA    145.1.125.5/32 [110/2] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA    145.1.125.1/32 [110/66] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA    145.1.125.2/32 [110/66] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

    O IA 192.10.1.0/24 [110/131] via 145.1.48.8, 00:03:13,
    FastEthernet0/1

         150.1.0.0/16 is variably subnetted, 7 subnets, 3 masks

    O       150.1.7.7/32 [110/68] via 145.1.48.8, 00:03:14,
    FastEthernet0/1

    O       150.1.3.3/32 [110/131] via 145.1.48.8, 00:03:14,
    FastEthernet0/1

    O       150.1.2.2/32 [110/131] via 145.1.48.8, 00:03:14,
    FastEthernet0/1

    O       150.1.1.1/32 [110/67] via 145.1.48.8, 00:03:14,
    FastEthernet0/1

    O IA    150.1.0.0/20 [110/2] via 145.1.48.8, 00:00:05,
    FastEthernet0/1

    Rack1R4(config-router)#

     

    HTH,

     

     



    Scott Morris, 
    CCIE4 #4713, JNCIE-M #153, JNCIS-ER, CISSP, et al.

    JNCI-M/JNCI-ER

    Senior CCIE Instructor



    [email protected]

     

     

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    From: [email protected]
    [mailto:[email protected]] On Behalf Of deadheadblues

    Sent: Sunday, February 08, 2009 4:29 AM

    To: [email protected]

    Subject: Re: [rs-ml-4] Task 4.5 (OSPF area range)

     

    It is impossible to do, must be a typo.







    Internetwork Expert - The Industry Leader in CCIE Preparation

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  • Hi scott

    i wasted ages on this too, and your solution doesn't summarise R3's Loopback either (see exert below) as the question requests. I think its a typo/cut and paste mistake in the Mock labs to be honest. Its a bit annoying when you're trying to test yourself for time etc. Maybe it can be fixed up for the next guy, or you can further explain how your solution meets the requirements of the question..... below from your output..


    O       150.1.7.7/32 [110/68] via 145.1.48.8, 00:03:14, FastEthernet0/1

    O       150.1.3.3/32 [110/131] via 145.1.48.8, 00:03:14, FastEthernet0/1

    O       150.1.2.2/32 [110/131] via 145.1.48.8, 00:03:14, FastEthernet0/1

    O       150.1.1.1/32 [110/67] via 145.1.48.8, 00:03:14, FastEthernet0/1

    O IA    150.1.0.0/20 [110/2] via 145.1.48.8, 00:00:05, FastEthernet0/1

     

    Cheers

    Andy

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