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Forums » CCIE Forums » CCIE Routing & Switching Technical » Virtual-Link OSPF
Latest post 07-02-2009 8:05 AM by DarrellEscola. 5 replies.
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  • 07-01-2009 11:57 PM

    Virtual-Link OSPF

    Reply Contact

    Hi,

    Very basic question. I think not needed. But want to get some opinion. As I seen some configs with virtual link for below.

    R1 and R4 is in area 0

    R1 and R2 is in Area 25.

    Do we need a virtual link between R1 and R2?

     
    • Post Points: 50

  • 07-02-2009 1:41 AM In reply to

    Re: Virtual-Link OSPF

    Reply Contact

    I can't see why would you want Virtual-Link (VL) between R1 (ABR) and R2, unless R2 also belongs to some other Area :)

     

    What was always bothering my mind is - can we have Area30 connected via VL to Area0?

    Do we need to set up VL between R2 and R1 and connect Area20 before and then VL between R3 and R2? Or is there some other way?

    ---Area0---(R1)---Area10---(R2)---Area20---(R3)---Area30---

    Andrius
    • Post Points: 20

  • 07-02-2009 5:30 AM In reply to

    Re: Virtual-Link OSPF

    Reply Contact

    foysol_bgd:

    Hi,

    Very basic question. I think not needed. But want to get some opinion. As I seen some configs with virtual link for below.

    R1 and R4 is in area 0

    R1 and R2 is in Area 25.

    Do we need a virtual link between R1 and R2?

     

     

    Well, that depends on your physical topology, among other things.  Do you have a specific example?
    • Post Points: 5

  • 07-02-2009 7:15 AM In reply to

    Re: Virtual-Link OSPF

    Reply Contact

    Based on the limited info provide VL is not needed.  If there is more to the story my answer would change

    andrius.adamavicius:
    ---Area0---(R1)---Area10---(R2)---Area20---(R3)---Area30---

     

    1. Use R1-R2 VL to bring area 0 to R2 (now R2 is an ABR)

    2. Use R2-R3 VL to bring area 0 to R3 (now R3 is an ABR)

    So AREA 30 is connected to the backbone
    • Post Points: 20

  • 07-02-2009 7:20 AM In reply to

    Re: Virtual-Link OSPF

    Reply Contact

    thanks John.
    • Post Points: 5

  • 07-02-2009 8:05 AM In reply to

    Re: Virtual-Link OSPF

    Reply Contact

    A virtual-link is always in area 0 - if area 25 is discontiguous because R1 and R2 are not directly connected, and it is necessary for R1 and R2 to have the same database for area 25, a tunnel in area 25 could be created between R1 and R2. Be careful that this does not result in routing through the tunnel for the tunnel destination, causing the tunnel to flap.

    foysol_bgd:

    Hi,

    Very basic question. I think not needed. But want to get some opinion. As I seen some configs with virtual link for below.

    R1 and R4 is in area 0

    R1 and R2 is in Area 25.

    Do we need a virtual link between R1 and R2?

     

    Darrell A. Escola, CCIE #23173 (R&S)
    B.Sc. Information Technology
    MCSE, MCDBA, MCSD, Linux+
    • Post Points: 5
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