NSX-T Link Failover Testing: Avoid These Common Mistakes

As a network administrator, it’s essential to ensure that your NSX-T deployment is functioning correctly and that link failover testing is done appropriately. However, I recently discovered that I was doing things the wrong way, and I’m here to share my experiences with you. In this blog post, I’ll discuss the common mistakes to avoid when testing link failover in NSX-T deployments.

The Wrong Way of Testing Link Failover

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I was under the impression that testing convergence by disconnecting Edge node virtual NIC one by one was the correct way of checking link failover and testing convergence NSX-T deployment. However, this method is not recommended and can lead to incorrect results.

The Correct Way of Testing Link Failover

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To correctly test link failover in NSX-T deployments, it’s essential to bring down the physical NIC card of the host instead of disconnecting Edge node virtual NIC one by one. This method ensures that the failure is isolated and doesn’t affect other paths. Additionally, for complete edge node failure, put the edge node in maintenance mode instead of disabling its virtual NICs.

Why You Should Avoid Testing Convergence with Virtual NIC Disconnection

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Testing convergence by disconnecting Edge node virtual NIC one by one can lead to incorrect results for several reasons:

1. **Multiple Paths**: NSX-T deployments often have multiple paths, and disconnecting a single virtual NIC may not cause the traffic to converge on another path as expected.

2. **Dynamic Routing**: The Edge nodes in NSX-T deployments use dynamic routing, which means that the traffic can be routed through any available path based on network conditions and availability. Disconnecting a single virtual NIC may not cause the traffic to converge on another path as expected.

3. **Node Failure**: If you disconnect a virtual NIC and the Edge node fails, it may take longer to detect the failure and recover from it. This can lead to extended downtime and potential data loss.

The Benefits of Correctly Testing Link Failover

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Correctly testing link failover in NSX-T deployments has several benefits:

1. **Reduced Downtime**: By bringing down the physical NIC card of the host instead of disconnecting Edge node virtual NIC one by one, you can reduce downtime and ensure that the failure is isolated.

2. **Improved Network Performance**: Correctly testing link failover ensures that network performance is not affected by incorrect test results.

3. **Reliable Deployment**: By avoiding common mistakes in testing link failover, you can ensure a reliable deployment and minimize the risk of data loss or extended downtime.

Conclusion

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Testing link failover in NSX-T deployments is crucial to ensure that your network is functioning correctly. However, it’s essential to avoid common mistakes like testing convergence by disconnecting Edge node virtual NIC one by one. Instead, bring down the physical NIC card of the host and put the edge node in maintenance mode for complete failure. By following these best practices, you can reduce downtime, improve network performance, and ensure a reliable deployment.