300-420 Question 136
Single answerAn enterprise network is configured with OSPF as the primary IGP in the core and EIGRP in the distribution layer. The network administrator is tasked with redistributing routes between OSPF and EIGRP to ensure end-to-end connectivity. To prevent routing loops during redistribution, which approach is the most appropriate?
- A
Use route tags to identify and filter external routes during redistribution.
- B
Redistribute all routes without applying any filters or tags.
- C
Enable mutual redistribution between OSPF and EIGRP and set the administrative distance to 1 for redistributed routes.
- D
Use a default route instead of redistributing routes between OSPF and EIGRP.
Show answer and explanation
Correct answer: A
Explanation
When redistributing routes between protocols like OSPF and EIGRP, routing loops can occur if routes are re-learned by their originating protocol. The best practice to prevent this is to use route tags. Route tags allow the administrator to mark routes during redistribution and filter them out when they are rediscovered by the originating protocol, ensuring a loop-free redistribution process.
- A. Correct.
Using route tags to identify and filter external routes during redistribution is an effective way to prevent routing loops. Tags can help prevent routes from being re-advertised into their originating protocol.
- B. Incorrect.
Redistributing all routes without any filters or tags increases the likelihood of routing loops since there is no mechanism to prevent routes from being re-learned by their originating protocol.
- C. Incorrect.
Setting the administrative distance to 1 for redistributed routes does not prevent routing loops and can cause unintended consequences, such as overriding protocol preference for native routes.
- D. Incorrect.
Using a default route instead of redistributing routes is not suitable for scenarios that require specific route information to be shared between protocols.