300-420 Question 125
Single answerAn enterprise network consists of multiple branches connected to the headquarters via an MPLS provider network. The network administrator wants to ensure that only specific routes from the branches are advertised to the headquarters and prevent unnecessary routes from propagating. Which route filtering method would be most appropriate to achieve this requirement within a BGP configuration?
- A
Use prefix lists to filter incoming and outgoing BGP updates.
- B
Use route redistribution to control route advertisement.
- C
Configure route maps with specific match conditions and apply them to BGP updates.
- D
Enable BGP community attributes for route filtering.
Show answer and explanation
Correct answer: C
Explanation
To filter specific routes between branches and headquarters in a BGP configuration, route maps offer the most flexibility and control. They allow the network administrator to define precise match conditions and actions for route advertisement. Prefix lists, while useful for basic filtering, lack the advanced capabilities that route maps provide, making route maps the ideal choice for this scenario.
- A. Incorrect.
Prefix lists are commonly used for filtering routes, but they are more static in nature and lack the flexibility of advanced filtering capabilities like route maps.
- B. Incorrect.
Route redistribution is used to exchange routes between different routing protocols, but it is not specifically designed for filtering routes within BGP.
- C. Correct.
Route maps provide a highly flexible and granular mechanism to filter routes based on conditions such as prefixes, next-hop, community attributes, and more. They are the most appropriate method for this scenario.
- D. Incorrect.
BGP community attributes are useful for tagging routes and influencing routing decisions, but they are not a direct filtering mechanism by themselves.