300-440 Question 35
Single answerA network engineer is tasked with segmenting a network into multiple virtual routing domains using VRF-Lite. The engineer has configured two VRFs, 'VRF-A' and 'VRF-B', on a Cisco router. However, devices in 'VRF-A' cannot communicate with devices in 'VRF-B'. What step should the engineer take to resolve this issue while keeping the VRFs isolated?
- A
Configure route leaking between VRF-A and VRF-B using route-target import and export.
- B
Assign the same RD (Route Distinguisher) to both VRF-A and VRF-B.
- C
Enable OSPF between VRF-A and VRF-B.
- D
Use static routes to establish communication between VRF-A and VRF-B.
Show answer and explanation
Correct answer: A
Explanation
VRF-Lite creates isolated routing instances on a single router, and by default, these VRFs cannot communicate with one another. To allow selective communication while maintaining isolation, route leaking via route-target import/export is the appropriate solution. This method enables specific routes to be shared between VRFs without merging their routing tables or compromising their isolation.
- A. Correct.
Configuring route leaking with route-target import/export allows specific routes to be shared between VRFs without merging them, which resolves the communication issue while keeping VRFs isolated.
- B. Incorrect.
Assigning the same RD to both VRFs is incorrect, as the RD is used for unique route identification within a VRF. This action would merge the VRFs rather than keep them isolated.
- C. Incorrect.
Enabling OSPF between VRFs is not a valid option because VRFs are separate routing instances, and routing protocols like OSPF cannot directly communicate across VRFs without route leaking.
- D. Incorrect.
Using static routes would not work directly between VRFs because VRFs maintain separate routing tables. Communication requires route leaking for route visibility across VRFs.