300-415 Question 148
Select 3An enterprise is deploying Cisco SD-WAN and plans to integrate OSPF between the overlay network and a site’s LAN. The site’s LAN is using OSPF as its IGP. The administrator has configured OSPF redistribution on the SD-WAN edge router, but the OSPF routes from the LAN are not appearing in the overlay network. Which of the following steps should the administrator take to resolve the issue?
- A
Ensure that the OSPF interface is configured as 'passive' on the SD-WAN edge router.
- B
Verify that the OSPF area type is not configured as a stub or totally stubby area on the LAN.
- C
Check if OMP (Overlay Management Protocol) is advertising the redistributed OSPF routes to the SD-WAN fabric.
- D
Enable mutual redistribution between OSPF and OMP on the SD-WAN edge router.
- E
Verify that the correct OSPF process ID is used for redistribution on the SD-WAN edge router.
Show answer and explanation
Correct answers: B, C, D
Explanation
For OSPF routes to appear in the SD-WAN overlay network, the administrator must ensure proper redistribution between OSPF and OMP. This includes checking OSPF area types (to avoid restrictions like stub areas), confirming that OMP is advertising the routes, and enabling mutual redistribution. Configuring the OSPF interface as 'passive' is unrelated to this issue, and verifying the OSPF process ID is generally a basic step that is assumed to be correct since redistribution has already been attempted.
- A. Incorrect.
Configuring the OSPF interface as 'passive' prevents OSPF from forming adjacencies and exchanging routes, but this is unrelated to the redistribution issue in this scenario.
- B. Correct.
If the LAN OSPF area is configured as a stub or totally stubby area, it may block certain external routes, which could prevent redistribution into OMP.
- C. Correct.
OMP is responsible for advertising redistributed routes in the SD-WAN fabric. If OMP is not properly configured, the OSPF routes will not propagate to the overlay network.
- D. Correct.
Mutual redistribution between OSPF and OMP is necessary to ensure that OSPF routes from the LAN are advertised into the SD-WAN overlay and vice versa.
- E. Incorrect.
The OSPF process ID must match the ID used in the redistribution configuration, but this is less likely to be the root cause in the given scenario since redistribution has already been attempted.