* Goal Analysis:
* Requirement:
* The route to 192.168.3.0/24 must exist in R1's and R3's routing tables.
* The route must not exist in R2's routing table.
* This requires filtering to ensure the route is either:
* Blocked on R2's routing table (via filtering on R2), or
* Blocked before it is advertised to R2.
* Analysis of Each Option:
* Option A (Filter-policy on R2 for filtering received routes):
* Applying a filter-policy on R2 to filter received routes will block the route from entering R2's routing table but still allow it to propagate to R3.
* This meets the requirement.
* Option B (Filter-policy on R2 for filtering the routes to be advertised):
* Blocking the advertisement of routes from R2 to other routers does not affect the routes received by R2 itself.
* This does not meet the requirement but does not affect the propagation to R3.
* This is valid if the received route is blocked.
* Option C (Filter-policy on R1 for filtering the routes to be imported):
* If the route is filtered on R1 during the import phase, the route will not exist in R1's routing table and thus cannot be advertised to either R2 or R3.
* This fails to meet the requirement because the route must exist in R1's and R3's routing tables.
* Option D (Filter-policy on R1 for filtering the imported routes to be advertised):
* Filtering routes on R1 before advertising to R2 will prevent R2 from receiving the route but allow R1 to advertise the route to R3.
* This meets the requirement.
* Correct Option:
* C (Filter-policy on R1 for filtering the routes to be imported): This will prevent the route from existing in both R1 and R3, violating the stated requirement.
References:
* HCIA-Datacom Study Guide, Chapter: OSPF Route Filtering
* Huawei OSPF Configuration and Filtering Methods