VMware ESXi and vSphere Cluster Management

Monitor Network Performance in VMware ESXi with vCenter Server Charts

Learn how to use vCenter Server Advanced performance charts to monitor real-time receive, transmit, and usage metrics for ESXi hosts and virtual machines.

vCenter Server performance charts provide a graphical way to measure network activity for supported vSphere inventory objects. By viewing incoming and outgoing traffic, you can determine whether an ESXi host or virtual machine is receiving, transmitting, or continuously handling a high volume of network data.

This lesson shows how to create a real-time network chart in the Advanced performance view. It also explains which inventory objects support network counters and how to interpret the resulting lines.

Why Monitor Network Performance?

Network monitoring helps you understand how much traffic a selected object is handling. In vCenter Server, network performance charts can display measurements such as the Data receive rate, the Data transmit rate, and Usage.

Receive and transmit measurements answer different questions:

Data receive rate: How quickly the selected object is receiving network data.
Data transmit rate: How quickly the selected object is sending network data.
Usage: An overall network-use indicator for the selected object.

Monitoring both directions is important. A virtual machine running a backup service might transmit large amounts of data, while a web or database workload might show a different balance between received and transmitted traffic. Spikes can identify bursts of activity, while sustained high values can indicate a consistently busy workload.

Host Monitoring Versus Virtual Machine Monitoring

An ESXi host is the hypervisor that runs virtual machines. A host-level chart shows network activity associated with that individual host, including the aggregate activity handled at the host level.

A virtual machine is a guest workload running on an ESXi host. A VM-level chart focuses on that specific workload rather than the host's total network activity.

For example, select an ESXi host when investigating whether the host is handling unusually high network traffic. Select an individual virtual machine when determining whether one workload is primarily receiving or transmitting data. Do not interpret a host chart as a cluster-wide or datacenter-wide chart.

Inventory Objects That Support Network Counters

Network performance counters are available for individual ESXi hosts and virtual machines. They are not available as network-counter sources for datacenters, clusters, or resource pools.

Inventory object | Network counters available | Notes

ESXi host | Yes | Shows network activity for the selected host.

Virtual machine | Yes | Shows network activity for the selected VM.

Datacenter | No | Select an individual host or VM instead.

Cluster | No | Select an individual host or VM instead.

Resource pool | No | Select an individual host or VM instead.

Selecting a supported object is necessary before configuring the chart because the available counters depend on the object type. If you start with a datacenter, cluster, or resource pool, the required network counters will not be available for selection.

Open the Advanced Performance View

In the vCenter Server inventory, select the target ESXi host or virtual machine.
Open the Monitor area for the selected object.
Open Performance.
Choose the Advanced performance view.
Open Chart Options to create or customize the performance chart.

The Advanced performance view is the chart area used to choose the metric, timespan, chart type, object, and individual counters.

Configure a Real-Time Network Chart

Use the following settings to observe current or recent network behavior:

In Chart Options, choose Network as the metric or performance category.
Set the chart timespan to Real-time.
Choose Line Graph as the chart type.
Select the intended ESXi host or virtual machine as the chart object.
Add the Data receive rate counter.
Add the Data transmit rate counter.
Add the Usage counter.
Apply or display the chart.

A Line Graph plots each selected counter over time. Using Real-time makes the chart suitable for observing current activity rather than examining a long-term historical trend.

Network Performance Counter Reference

Counter | What it indicates | Typical monitoring use

Data receive rate | The rate of network data received by the selected ESXi host or virtual machine. | Identify inbound traffic, download activity, request responses, or receive-side bursts.

Data transmit rate | The rate of network data transmitted by the selected ESXi host or virtual machine. | Identify outbound traffic, uploads, replication, backups, or transmit-side bursts.

Usage | A network utilization-related indicator for the selected object. | Assess the object's overall network-use level alongside receive and transmit rates.

Interpret the Network Line Graph

Start by identifying the lines for Data receive rate and Data transmit rate. Compare their relative levels and changes over time:

If the receive line is higher, inbound traffic is dominant during that interval.
If the transmit line is higher, outbound traffic is dominant during that interval.
Short spikes indicate brief bursts of network activity.
Sustained high activity indicates that the selected object is continuously handling a large amount of traffic.
Low-activity periods indicate little network data movement for the selected object during those intervals.

Use the Usage counter as an additional overall indicator, but interpret it together with the receive and transmit lines. A high Usage value is more useful when you can also see which traffic direction is contributing to the activity.

Always relate the result to the object selected before opening Chart Options. A VM chart describes that VM's observed network activity. A host chart describes the selected host's activity. Neither chart should automatically be treated as a measurement for the entire cluster or datacenter.

Example: Check Current Host Network Traffic

Select an ESXi host in the vCenter inventory.
Open Monitor, then Performance, and choose Advanced.
Open Chart Options.
Choose Network, set the timespan to Real-time, and select Line Graph.
Confirm that the selected chart object is the intended ESXi host.
Add Data receive rate, Data transmit rate, and Usage.
Review whether inbound or outbound traffic is dominant and whether the activity remains consistently high.

Example: Check Network Activity for a Virtual Machine

Select the virtual machine instead of an ESXi host.
Open Monitor, Performance, and Advanced.
Open Chart Options and choose Network.
Set the timespan to Real-time and the chart type to Line Graph.
Confirm that the VM is the selected chart object.
Add Data receive rate, Data transmit rate, and Usage.
Compare the receive and transmit lines to determine whether the VM is primarily receiving or sending data.

Real-Time and Historical Monitoring

Real-time is a short-term performance-chart timespan intended for observing current or recent activity. It is useful when validating whether traffic is occurring now, checking a suspected burst, or watching a workload while a test is running.

Performance statistics can also be considered over historical time ranges when investigating recurring patterns, changes in workload behavior, or earlier incidents. The historical views and level of detail depend on the performance statistics retained by vCenter Server. Use an appropriate historical range when the question concerns behavior over hours, days, or another longer period.

Troubleshooting Network Charts

Network counters are not shown

The selected object may be a datacenter, cluster, or resource pool. These objects do not provide the required network counters.

Select an individual ESXi host or virtual machine, open its Advanced performance view again, and configure the network chart from that object.

The desired traffic measurements are missing

The Network metric or one or more required counters may not have been selected in Chart Options.

Open Chart Options, choose Network, verify the selected host or VM, and add Data receive rate, Data transmit rate, and Usage.

The chart is not suitable for immediate activity

A non-real-time timespan may be selected. Set the chart timespan to Real-time when you need to observe current or recent traffic behavior.

Exam-Relevant Notes

Network performance counters are available for ESXi hosts and virtual machines.
Datacenters, clusters, and resource pools are not valid sources for these network counters.
The navigation path is Monitor > Performance > Advanced, followed by Chart Options.
Choose Network, Real-time, and Line Graph for a real-time network chart.
Data receive rate represents incoming traffic.
Data transmit rate represents outgoing traffic.
Usage provides an overall network-use indicator for the selected object.
Interpret the chart according to the selected host or VM, not as an automatic cluster or datacenter summary.

For broader vSphere administration study, see the VMware ESXi online course. If a host is not yet managed by vCenter Server, review how to add an ESXi host to the vCenter Server inventory.