LAB: OSPF Route Preference

He're you'll be tweaking some more behavior of OSPF to gain some effiencies.


  1. Locate a destination in your routing table which has multiple equal cost paths and was populated by OSPF
  2. For areas 0.0.0.1, 0.0.0.2 and 0.0.0.3, log into one of those areas internal routers that connects to an ABR for which your router serves as the ABR
  3. What is the best route from one side of the area to the other side? (i.e. from R1 to R2 in area 0.0.0.1, R6 to R8 in area 0.0.0.2 or R9 to R10 in area 0.0.0.3?
  4. Perform a traceroute from one side of the area to the other and confirm the path
  5. For your area, configure the backbone link that connects the two ABRs together to participate in another area without harming the integrity of your backbone
  6. What is the best route from one side of the area to the other side? (i.e. from R1 to R2 in area 0.0.0.1, R6 to R8 in area 0.0.0.2 or R9 to R10 in area 0.0.0.3?
  7. Perform a traceroute from one side of the area to the other and confirm the path is more efficient
  8. Compare your Router LSA that is being advertised into the backbone with the Router LSA that is being advertised into area 0.0.0.1, 0.0.0.2 or 0.0.0.3
  9. Change your router to prefer BGP routes more than OSPF external routes (Hint: BGP has a default preference of 170 in Junos)
  10. Advertise your loopback interface out as part of your Router LSA
  11. Is your router still sending External LSAs out advertising your Loopback interface?

Stuck: