ANS-C01 Question 371
Select 2Your organization has a hybrid cloud setup where an on-premises data center communicates with workloads hosted in Amazon VPC through a Site-to-Site VPN connection. Users are reporting intermittent performance issues when transferring large files from on-premises to the VPC. Upon investigation, you observe that the average packet size is close to 1500 bytes. Which of the following actions can help address the performance issues while adhering to network constraints?
- A
Enable Path MTU Discovery (PMTUD) on both the on-premises network and the VPC to dynamically adjust the packet size.
- B
Increase the MTU of the VPN tunnel to support jumbo frames.
- C
Reduce the MTU size on the on-premises network and the VPC to 1400 bytes to avoid fragmentation.
- D
Implement a TCP optimization tool to manage retransmissions and improve throughput.
- E
Disable ICMP on both the on-premises router and the VPC to prevent unnecessary overhead.
Show answer and explanation
Correct answers: A, C
Explanation
The performance issues are likely caused by MTU mismatches or fragmentation due to the packet size nearing the default MTU of 1500 bytes. Enabling PMTUD allows the network to dynamically adjust the MTU, while reducing the MTU size to 1400 bytes proactively avoids fragmentation. Increasing the MTU or disabling ICMP is not applicable or counterproductive in this scenario.
- A. Correct.
Enabling Path MTU Discovery (PMTUD) helps dynamically determine the optimal MTU size along the path, reducing fragmentation and improving performance.
- B. Incorrect.
Increasing the MTU of the VPN tunnel to support jumbo frames is not feasible in this case because AWS Site-to-Site VPN does not support jumbo frames.
- C. Correct.
Reducing the MTU size proactively ensures that no packets are fragmented during transmission, which can alleviate performance issues.
- D. Incorrect.
While TCP optimization tools can help in general, they do not directly address the MTU-related issue described in the scenario.
- E. Incorrect.
Disabling ICMP would prevent PMTUD from functioning correctly, potentially worsening the issue.