Module Causes M4250-40G8XF Control Plane To Crash

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Introduction

The M4250-40G8XF is a high-performance switch that plays a crucial role in various network environments. However, a recent issue has been reported where a module causes the control plane to crash. In this article, we will delve into the root cause of the problem, analyze the response times of the affected endpoints, and provide potential solutions to mitigate the issue.

Understanding the Issue

The module in question is polling the following endpoints every second:

  • GET /api/v1/device_info
  • GET /api/v1/swcfg_poe?portid=ALL
  • GET /api/v1/sw_portstats?portid=ALL

These endpoints are being polled at an interval of 1 second, which may seem reasonable at first glance. However, the response times of these endpoints are causing the control plane to crash.

Analyzing Response Times

To better understand the issue, we need to analyze the response times of the affected endpoints. We can use curl to fetch the response times of these endpoints.

Device Info Endpoint

curl -o /dev/null -s -w 'Establish Connection: %{time_connect}s\nTTFB: %{time_starttransfer}s\nTotal: %{time_total}s\n' \
--insecure \
--location 'https://10.0.22.202:8443/api/v1/device_info' \
--header 'Accept: application/json' \
--header 'Authorization: Bearer [...]'

Establish Connection: 0.004423s
TTFB: 1.121661s
Total: 1.122025s

As we can see, the device_info endpoint takes approximately 1.12 seconds to respond.

SW Config POE Endpoint

curl -o /dev/null -s -w 'Establish Connection: %{time_connect}s\nTTFB: %{time_starttransfer}s\nTotal: %{time_total}s\n' \
--insecure \
--location 'https://10.0.22.202:8443/api/v1/swcfg_poe?portid=ALL'  \
--header 'Accept: application/json' \
--header 'Authorization: Bearer [...]'

Establish Connection: 0.009649s
TTFB: 0.057777s
Total: 0.057863s

The swcfg_poe endpoint takes approximately 0.06 seconds to respond.

SW Port Stats Endpoint

curl -o /dev/null -s -w 'Establish Connection: %{time_connect}s\nTTFB: %{time_starttransfer}s\nTotal: %{time_total}s\n' \
--insecure \
--location 'https://10.0.22.202:8443/api/v1/sw_portstats?portid=ALL'  \
--header 'Accept: application/json' \
--header 'Authorization: Bearer [...]'

Establish Connection: 0.004475s
TTFB: 5.921681s
Total: 5.926355s

The sw_portstats endpoint takes approximately 5.93 seconds to respond.

Identifying the Root Cause

As we can see, the device_info and portstats endpoints are the biggest problems here. They don't even return a response before the module hits them again. This doesn't seem to matter on a 24-port switch, so we suspect something inside the control plane takes longer to gather the port stats.

Potential Solutions

Based on our analysis, we can propose the following potential solutions to mitigate the issue:

Solution 1: Avoid Using setInterval and Use setTimeout Instead

One potential solution is to avoid using setInterval and use setTimeout instead. This means that there will always be a 1-second delay between a request finishing and the next one starting.

function fetchDeviceInfo() {
    // Fetch device info
    fetch('/api/v1/device_info')
        .then(response => response.json())
        .then(data => {
            // Process data
            console.log(data);
            // Fetch device info again after 1 second
            setTimeout(fetchDeviceInfo, 1000);
        })
        .catch(error => {
            console.error(error);
        });
}

fetchDeviceInfo();

Solution 2: Abort Requests and Use Caching

Another potential solution is to abort requests and use caching. This means that the callback function will return the cached result regardless of when the actual response completes.

let cachedResult = null;

function fetchDeviceInfo() {
    // Fetch device info
    fetch('/api/v1/device_info')
        .then(response => response.json())
        .then(data => {
            // Cache result
            cachedResult = data;
            // Process data
            console.log(data);
            // Fetch device info again after 1 second
            setTimeout(fetchDeviceInfo, 1000);
        })
        .catch(error => {
            console.error(error);
        });
}

function callback() {
    // Return cached result
    return cachedResult;
}

callback();

Conclusion

Q: What is the M4250-40G8XF switch?

A: The M4250-40G8XF is a high-performance switch that plays a crucial role in various network environments.

Q: What is the issue with the M4250-40G8XF switch?

A: The issue with the M4250-40G8XF switch is that a module causes the control plane to crash due to high response times of the affected endpoints.

Q: Which endpoints are affected?

A: The device_info, swcfg_poe, and sw_portstats endpoints are affected.

Q: What are the response times of the affected endpoints?

A: The response times of the affected endpoints are:

  • device_info: approximately 1.12 seconds
  • swcfg_poe: approximately 0.06 seconds
  • sw_portstats: approximately 5.93 seconds

Q: What are the potential solutions to mitigate the issue?

A: The potential solutions to mitigate the issue are:

  1. Avoid using setInterval and use setTimeout instead.
  2. Abort requests and use caching.

Q: How can I implement the first solution?

A: To implement the first solution, you can use the following code:

function fetchDeviceInfo() {
    // Fetch device info
    fetch('/api/v1/device_info')
        .then(response => response.json())
        .then(data => {
            // Process data
            console.log(data);
            // Fetch device info again after 1 second
            setTimeout(fetchDeviceInfo, 1000);
        })
        .catch(error => {
            console.error(error);
        });
}

fetchDeviceInfo();

Q: How can I implement the second solution?

A: To implement the second solution, you can use the following code:

let cachedResult = null;

function fetchDeviceInfo() {
    // Fetch device info
    fetch('/api/v1/device_info')
        .then(response => response.json())
        .then(data => {
            // Cache result
            cachedResult = data;
            // Process data
            console.log(data);
            // Fetch device info again after 1 second
            setTimeout(fetchDeviceInfo, 1000);
        })
        .catch(error => {
            console.error(error);
        });
}

function callback() {
    // Return cached result
    return cachedResult;
}

callback();

Q: Can I contribute to the fixes?

A: Yes, you can contribute to the fixes. We have limited availability to contribute to the fixes, but we appreciate any help we can get.

Q: How can I report the issue?

A: You can report the issue by contacting our support team. We will do our best to assist you and provide a solution to the issue.

Conclusion

In conclusion, the M4250-40G8XF switch is experiencing an issue where a module causes the control plane to crash due to high response times of the affected endpoints. We have two potential solutions to mitigate the issue: avoiding the use of setInterval and using setTimeout instead, and aborting requests and using caching. We hope that these solutions will help to resolve the issue and improve the performance of the M4250-40G8XF switch.