300-420 Question 91
Select 3An enterprise network is designed with multiple VLANs and uses Spanning Tree Protocol (STP) to ensure a loop-free topology. The network has grown significantly, and the IT team is now facing scalability challenges with STP. Which of the following design strategies can help improve STP scalability in this scenario?
- A
Implement Multiple Spanning Tree Protocol (MSTP) to map multiple VLANs to a single spanning tree instance
- B
Increase the STP timers (Hello, Forward Delay, and Max Age) to reduce the frequency of topology changes
- C
Use Rapid Spanning Tree Protocol (RSTP) to speed up convergence and reduce the impact of topology changes
- D
Segment the Layer 2 domain using Layer 3 boundaries to limit the scope of STP
- E
Enable BPDU Guard on all access ports to prevent STP topology changes caused by misconfigurations
Show answer and explanation
Correct answers: A, C, D
Explanation
To enhance STP scalability in large networks, it is critical to reduce the number of spanning tree instances and limit the size of the Layer 2 domain. MSTP helps by consolidating multiple VLANs into fewer STP instances, while RSTP ensures faster convergence during topology changes. Additionally, segmenting the Layer 2 domain with Layer 3 boundaries minimizes the scope of STP, making the network more scalable. Other strategies like increasing timers or enabling BPDU Guard, while useful in specific scenarios, do not directly address scalability issues.
- A. Correct.
Implementing Multiple Spanning Tree Protocol (MSTP) allows the mapping of multiple VLANs to a single spanning tree instance, reducing the number of STP instances and improving scalability.
- B. Incorrect.
Increasing STP timers does not address scalability issues; it only slows down the protocol's responsiveness to changes, potentially causing delays in convergence.
- C. Correct.
Using Rapid Spanning Tree Protocol (RSTP) improves convergence times and reduces the impact of topology changes, making it a suitable choice for enhancing STP scalability.
- D. Correct.
Segmenting the Layer 2 domain using Layer 3 boundaries reduces the size of the STP domain, thereby limiting its scope and improving scalability.
- E. Incorrect.
Enabling BPDU Guard on access ports improves network stability and security but does not directly address scalability challenges in STP.