OSPF Area Question...I think

davenportdavenport Member Posts: 86 ■■□□□□□□□□
I believe this is more of a design question, but I'm not entirely sure. I've been working on my NP route recently, and labbing out EIGRP, OSPF, BGP, etc. I built a small GNS3 lab for OSPF, and after getting everything configured and working, I started adding different links between routers to change cost, test failover, etc. While doing this I added a serial link between two routers and it hit me, I don't know how you'd configure this. When adding the network statement, what area would you add this to (picture attached with an arrow pointing to the link). I apologize if the question is not clear, it's 4:30AM I've been studying for a while and I'm a bit worn out lol

Thanks for any help you can give


  • martell1000martell1000 Member Posts: 389
    first of all: this is not a recommended design as far as i read about ospf.

    but if you wish to do so put R8s one interface into area37. you will have then to establish a virtual link to area 0 if R8 does not have an interface in area 0.

    a virtual link will kinda "pull" area 0 to the router in question and make it work as an ABR. but i guess you have to be carefull with this topology to not cause any routing loops....
    And then, I started a blog ...
  • DevilWAHDevilWAH Member Posts: 2,997 ■■■■■■■■□□
    I would agree putting the linking interface on R8 (or R7) would cause the router to become a ABR.

    I am now going to play :) please keep us updated.
    • If you can't explain it simply, you don't understand it well enough. Albert Einstein
    • An arrow can only be shot by pulling it backward. So when life is dragging you back with difficulties. It means that its going to launch you into something great. So just focus and keep aiming.
  • mayhem87mayhem87 Member Posts: 73 ■■□□□□□□□□
    They had something similar in the INE videos for ospf. It wasn't called anything in particular from what I can remember and its more for redundancy. One of those routers are going to have to be in both areas. This allows for if the ABR from area 0 goes down you can then create a virtual link to the area that would be otherwise unreachable. IE The link from R3 goes down for some reason to area 38 but is still connected to area 37. This would cause for area 38 to no longer be reachable. You could then take the router that has a interface in both areas and use it as an ABR for the virtual link. Connecting area 38 back to area 0 over area 37 until the serial link from R3 comes back up.
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