How can I reduce Azure VM latency with VPN connection?

Hello @SHACH1d

Welcome to the Microsoft Q&A and thank you for posting your questions here. Also, thank you for detail information.

Problem

I understand that you are having network latency using Azure VM with a VPN connection and you would like to reduce it.

Solution

To solve this challenge, you will need to understand that the kind of issue you are having with network latency between Azure virtual machines (VMs) can be influenced by various factors.

One of the solutions is what you've already done by enabled Accelerated Networking, which is great. This feature offloads network processing to dedicated hardware, reducing latency. Please, confirm that it's enabled for both the sender and receiver VMs.

STEPS

Some steps to optimize and troubleshoot latency are the following:

• Deploy your VMs within an Azure proximity placement group. PPGs keep VMs physically close to each other, minimizing latency. If you haven't done this yet, consider creating a PPG and placing your VMs in it.
• Evaluate if your current VM size is optimal for your workload. If not, consider using larger VM sizes. Larger VMs generally offer better performance due to increased resources.
• Review your network configuration. Firewalls, ExpressRoutes, and other network features can impact round-trip time. You will need to ensure that no network components are interfering with your bandwidth.
• Reduce the physical distance between end-users and the server. If possible, have end-users connect to VMs in the Azure region closest to them.
• Verify the Maximum Transmission Unit (MTU) value at the OS level on your server/VM. Incorrect MTU settings can affect latency.
• Sometimes resetting the VPN gateway can improve results. Consider doing this and retesting.

Now, compare test results against baselines and repeat tests after any changes to observe the impact on network latency. Keep in mind that VPN connections inherently introduce some latency due to encryption and routing overhead.

Accurate Measure

To measure network latency accurately, use tools like Latte (for Windows) or SockPerf (for Linux). These tools focus on TCP and UDP traffic, which are more relevant for application performance than ICMP-based tools like Ping¹. You can follow these steps to test network latency:

1. Latte (Windows):

• Install Latte.
• Run Latte on the receiver VM using the following command:
• latte -a <Receiver_IP>:<port> -i <iterations> Example: latte -c -a 10.0.0.4:5005 -i 65100

2. SockPerf (Linux):

• Install SockPerf.
• Run SockPerf on the receiver VM:
• sockperf server -i <Receiver_IP> -p <port> Example: sockperf server -i 10.0.0.4 -p 5005

References

For more reading and detail steps about some of the provided solution, kindly use the links below.

Source: Test network latency between Azure VMs. Accessed, 6/29/2024.

Source: Validate VPN throughput to a virtual network. Accessed, 6/29/2024.

Source: TCP/IP performance tuning for Azure VMs. Accessed, 6/29/2024.

Source: What is your Azure VPN Throughput. Accessed, 6/29/2024.

Accept Answer

I hope this is helpful! Do not hesitate to let me know if you have any other questions.

** Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful ** so that others in the community facing similar issues can easily find the solution.

Best Regards,

Sina Salam