Troubleshooting Poor Network Throughput on vSphere vSwitch

B.

In this scenario, the vSphere administrator has noticed poor network throughput for multiple port groups that reside on a vSwitch with multiple physical uplinks (vmnics) on a particular ESXi host. It is important to note that the configuration on this ESXi host is identical to other hosts that are working properly in the same cluster.

To troubleshoot this issue, the administrator can follow these steps:

1. Verify network connectivity: Ensure that the ESXi host has network connectivity to the other hosts in the cluster, as well as to other network devices, such as routers and switches. This can be done by pinging other devices from the ESXi host and verifying that the pings are successful.

2. Check vSwitch configuration: Verify that the vSwitch on the problematic ESXi host is configured identically to the vSwitches on the other hosts in the cluster. Check the number of physical uplinks (vmnics) configured on the vSwitch and verify that the configuration is the same on all hosts.

3. Check physical network configuration: Verify that the physical network configuration is the same on the problematic ESXi host as it is on the other hosts in the cluster. Check the physical switch configuration, including the number of uplinks and port configurations, to ensure that they are consistent across all hosts.

4. Check virtual machine network configuration: Verify that the virtual machines connected to the port groups on the problematic ESXi host are configured identically to the virtual machines on the other hosts in the cluster. Check the network settings on the virtual machines, including IP addresses and DNS settings.

5. Check network performance: Use network monitoring tools, such as netperf or iperf, to measure network performance between the problematic ESXi host and other hosts in the cluster. This will help identify any network performance issues and determine whether the problem is with the ESXi host or the network.

Based on these steps, it is clear that adding additional port groups to the vSwitch or adding additional resources to the virtual machines that are powered on (options A and B) would not help in resolving the network throughput issue. Restarting Management agents in ESXi Direct Console User Interface (DCUI) (option C) might help in resolving certain issues, but it is not likely to help in this case. Therefore, the best option is to alter the failover order of the vmnics until a bad vmnic is found (option D). By doing this, the administrator can identify the vmnic that is causing the poor network throughput and take corrective action.