300-420 Question 9
Select 3You are designing a large-scale enterprise network that utilizes IS-IS as the IGP. The network will consist of multiple areas and require scalability while ensuring stability and security. Which of the following design considerations should you implement to achieve these goals?
- A
Use a hierarchical area structure with Level 1 and Level 2 separation.
- B
Enable wide metrics to support high-bandwidth links and scalability.
- C
Disable authentication to simplify configuration and reduce processing overhead.
- D
Avoid configuring overload-bit in scenarios where the router's resources are limited.
- E
Implement IS-IS authentication to secure routing updates.
Show answer and explanation
Correct answers: A, B, E
Explanation
Designing a stable, secure, and scalable IS-IS routing architecture requires a combination of hierarchical design, modern feature utilization (such as wide metrics), and robust security mechanisms like authentication. Hierarchical area separation reduces routing overhead, wide metrics support scalability, and authentication ensures routing updates are secure. Avoiding best practices like overload-bit configuration in resource-constrained scenarios or disabling authentication can lead to instability and security vulnerabilities.
- A. Correct.
Using a hierarchical area structure with Level 1 and Level 2 separation improves scalability and reduces the size of the LSDB within each area, enhancing stability.
- B. Correct.
Enabling wide metrics allows IS-IS to support higher-bandwidth links and provides better scalability for modern networks.
- C. Incorrect.
Disabling authentication is not recommended as it exposes the network to potential attacks, compromising security.
- D. Incorrect.
Configuring the overload-bit is a best practice in scenarios where router resources are constrained. Avoiding it can lead to instability in the network.
- E. Correct.
Implementing IS-IS authentication secures routing updates, preventing unauthorized or malicious changes to the routing table.