Introduction/ Issue: Intermittent network connectivity drops on an Azure Virtual Machine (VM)
Why we need to do / Cause of the issue:
Network connectivity issues on an Azure VM can stem from various factors:
- Network Security Groups (NSGs) Configuration: Improper rules or misconfigured NSGs may block traffic intermittently.
- Virtual Network (VNet) Peering Issues: Misconfiguration in VNet peering or route tables may cause intermittent connectivity problems.
- Resource Limits: Exceeding network or resource limits set by the Azure subscription can lead to connectivity drops.
- VM Size and Performance: The VM size may be insufficient to handle the network load, especially during peak times.
- Azure Platform Issues: Sometimes, the issue could be due to underlying problems in the Azure infrastructure or region-specific outages.
How do we solve:
Check Network Security Groups (NSGs):
- Verify NSG Rules:
# az network nsg show –resource-group <ResourceGroup> –name <NSGName>
- Ensure that the inbound and outbound rules are correctly configured and not unintentionally blocking traffic.
- Review NSG Logs:
# az monitor diagnostic-settings list –resource-id /subscriptions/<subscription-id>/resourceGroups/<ResourceGroup>/providers/Microsoft.Network/networkSecurityGroups/<NSGName>
- Analyze the logs for any blocked or denied connections.
- Examine Virtual Network (VNet) Configuration:
- Check VNet Peering:
- az network vnet peering list –resource-group <ResourceGroup> –vnet-name <VNetName>
az network vnet peering list –resource-group <ResourceGroup> –vnet-name <VNetName>
Confirm that VNet peering is correctly set up and that the peering state is “Connected.”
Verify Route Tables:
az network route-table show –resource-group <ResourceGroup> –name <RouteTableName>
Ensure that custom routes do not misdirect traffic.
Monitor Resource Utilization:
- Check VM Metrics:
# az monitor metrics list –resource <VMResourceID> –metric “Network In” “Network Out”
Monitor network metrics to identify if the VM is hitting network throughput limits.
Scale VM Size: If the VM is under heavy load, consider resizing it to a larger size:
# az vm resize –resource-group <ResourceGroup> –name <VMName> –size <NewSize>
Update and Review VM Extensions:
- Check VM Extensions:
# az vm extension list –resource-group <ResourceGroup> –vm-name <VMName>
Ensure that VM extensions are properly configured and updated.
Review Extension Logs:
# az vm extension show –resource-group <ResourceGroup> –vm-name <VMName> –name <ExtensionName>
Analyze extension logs for errors or misconfigurations.
Verify Azure Platform Status:
- Check Azure Service Health:
# az servicehealth show –resource-group <ResourceGroup>
Look for any ongoing issues or maintenance activities in the Azure region.
Conclusion:
By systematically diagnosing the network connectivity issue on the Azure VM, we identified that outdated NSG rules were the primary cause of the problem. Through a series of checks, including network security group configurations, VNet peering, resource utilization monitoring, and platform status verification, we effectively resolved the issue. This structured approach ensured consistent network connectivity and minimized service disruptions.
