300-420 Question 13
Select 4An enterprise network is using EIGRP as its routing protocol. The network design team is tasked with creating a stable, secure, and scalable routing design. Which of the following design considerations should be implemented to achieve this goal?
- A
Use route summarization at key aggregation points to reduce the size of the routing table and improve convergence time.
- B
Enable EIGRP stub functionality on access layer routers to limit unnecessary route propagation.
- C
Configure authentication with MD5 or SHA to secure EIGRP neighbor relationships.
- D
Disable split horizon on all interfaces to allow for better route propagation in large networks.
- E
Set an appropriate variance value to enable EIGRP unequal-cost load balancing where necessary.
Show answer and explanation
Correct answers: A, B, C, E
Explanation
To create a stable, secure, and scalable EIGRP design, key considerations include using route summarization to simplify the routing table and improve convergence, enabling EIGRP stub functionality to limit unnecessary updates in specific parts of the network, and configuring authentication to secure neighbor relationships. Additionally, using EIGRP's unequal-cost load balancing feature (with variance) can improve bandwidth utilization without compromising the network's scalability. Disabling split horizon is not a recommended practice for most scenarios as it can introduce instability unless carefully controlled in specific topologies.
- A. Correct.
Route summarization helps reduce the size of the routing table, improves convergence times, and increases stability in the network by limiting the scope of route advertisements. This is a key design consideration for scalability and stability.
- B. Correct.
Enabling EIGRP stub functionality on access layer routers reduces the amount of unnecessary routing updates and minimizes the risk of instability. This is especially useful in a hub-and-spoke topology.
- C. Correct.
Configuring EIGRP authentication (e.g., MD5 or SHA) protects against unauthorized routers forming EIGRP neighbor relationships, ensuring security in the routing design.
- D. Incorrect.
Disabling split horizon on all interfaces is generally not recommended as it can lead to routing loops. Split horizon should only be disabled in specific scenarios, such as hub-and-spoke networks with non-broadcast multi-access (NBMA) configurations.
- E. Correct.
Setting an appropriate variance value enables EIGRP to use multiple paths with unequal costs, improving scalability and bandwidth utilization where necessary. However, this should be carefully implemented to avoid suboptimal routing.