VMware ESXi and vSphere Cluster Management
Configure Traffic Shaping Policies on VMware ESXi Standard Switches
Learn how to configure ESXi standard-switch traffic shaping, understand bandwidth and burst settings, apply port-group overrides, and troubleshoot outbound bandwidth limits.
Traffic shaping on an ESXi standard virtual switch controls how quickly virtual machines can transmit network traffic. It is useful when a workload should not consume all available uplink capacity or when administrators need a predictable outbound bandwidth policy.
This lesson covers standard virtual switches, not distributed-switch-specific traffic-control features. You should understand ESXi host administration, vSphere Client navigation, port groups, virtual network adapters, and the difference between inbound and outbound traffic.
Purpose of Virtual Switch Traffic Shaping
A standard virtual switch is an ESXi host-local virtual switch that connects virtual machines, port groups, and physical uplinks. A virtual NIC is the network adapter presented to a virtual machine. When a virtual NIC is connected to a standard switch, it can normally use the available capacity of the switch's associated physical uplink.
Traffic shaping is a policy that controls permitted network transmission rates for virtual network traffic. Traffic shaping is disabled unless an administrator enables and configures it.
Common reasons to enable it include:
- Preventing a noncritical workload from consuming excessive bandwidth.
- Controlling short-lived traffic bursts.
- Applying a predictable outbound bandwidth limit to a workload or group of workloads.
- Protecting capacity for latency-sensitive or business-critical applications.
Traffic Shaping Parameters
Three values define the policy: Average Bandwidth, Peak Bandwidth, and Burst Size. Bandwidth values use kilobits per second (Kbps). Burst Size uses kilobytes (KB).
How the Values Work Together
Think of the settings as a sustained rate, a short-term ceiling, and a burst allowance:
- Average Bandwidth establishes the long-term transmission rate.
- Peak Bandwidth sets the ceiling for short-term higher-rate transmission.
- Burst Size determines how much burst data can be sent before traffic is constrained toward the average policy.
A policy is valid only when Peak Bandwidth is equal to or greater than Average Bandwidth. For example, an Average Bandwidth of 50,000 Kbps and a Peak Bandwidth of 25,000 Kbps is invalid. Raise Peak Bandwidth to at least 50,000 Kbps.
Example: Limiting a Noncritical Virtual Machine
Suppose a noncritical virtual machine should normally use about 10 Mbps but may briefly transmit faster when it has available burst capacity:
This policy permits approximately 10 Mbps of sustained outbound transmission, allows temporary transmission up to approximately 20 Mbps during an allowed burst, and then constrains transmission as the burst allowance is consumed.
These values are policy limits, not a guarantee that the workload will always receive the average rate. Physical uplink congestion, host load, guest operating system behavior, and other network controls can still affect observed throughput.
Policy Scope and Precedence
You can configure traffic shaping at two scopes:
- Standard virtual switch scope: establishes a default policy for ports using that switch.
- Port group scope: establishes a policy for virtual machine network adapters connected through that port group.
A port group policy overrides the policy configured on its parent standard virtual switch. This makes switch-level settings useful for a default policy and port-group settings useful for exceptions.
Capabilities and Limitations
Configure a Standard Virtual Switch in the vSphere Web Interface
The exact labels can vary slightly between vSphere releases, but the workflow is generally as follows.
- Select the target ESXi host.
- Open Manage, then open Networking.
- Select the target standard virtual switch.
- Choose Edit for the switch.
- Open the Traffic Shaping settings.
- Enable traffic shaping.
- Enter Average Bandwidth in Kbps.
- Enter Peak Bandwidth in Kbps. Confirm that it is equal to or greater than Average Bandwidth.
- Enter Burst Size in KB.
- Save the changes.
After saving, check the resulting switch configuration and confirm that the intended virtual machines use this switch policy rather than a more specific port-group policy.
Configure a Port-Group-Specific Override
Use a port-group policy when only selected workloads need a different limit. For example, you might apply a general policy to the standard switch and lower values to an application-network port group.
- Select the target port group on the standard virtual switch.
- Edit the port group's traffic shaping settings.
- Enable traffic shaping for the port group.
- Define Average Bandwidth, Peak Bandwidth, and Burst Size with the correct units.
- Verify that Peak Bandwidth is not lower than Average Bandwidth.
- Save the port-group configuration.
Virtual machines connected to that port group use the port-group policy, which overrides the parent standard virtual switch policy.
Policy Planning and Validation
- Identify the target: Determine which workload, virtual NIC, or port group needs bandwidth control.
- Choose the sustained rate: Set Average Bandwidth from the workload's required normal throughput.
- Choose burst behavior: Set Peak Bandwidth and Burst Size according to acceptable temporary bursts.
- Confirm direction: Decide whether the requirement is egress-only. Standard virtual switch shaping does not limit ingress traffic.
- Check both scopes: Review the standard switch and the relevant port group to find the effective policy.
- Test representative traffic: Generate normal and burst-like workload traffic, then monitor throughput and application behavior.
- Review unintended effects: Confirm that throttling is intentional and distinguish policy limits from physical uplink congestion.
Troubleshooting
The Virtual Machine Exceeds the Expected Average Rate
- Determine whether the observed rate is a permitted temporary burst below Peak Bandwidth.
- Review Burst Size. A larger burst allowance permits more temporary high-rate transmission.
- Confirm that traffic shaping is enabled at the effective scope.
The Restriction Does Not Affect Traffic Entering the Virtual Machine
- Confirm the direction of the observed traffic.
- Remember that standard virtual switch traffic shaping affects outbound traffic only.
- Use an appropriate alternative networking control when inbound limiting is required.
The Interface Rejects the Rate Values
- Verify that Peak Bandwidth is not lower than Average Bandwidth.
- Verify units: Average Bandwidth and Peak Bandwidth use Kbps, while Burst Size uses KB.
A Port Group Does Not Follow the Switch Policy
- Inspect the port group's own traffic shaping configuration.
- Determine whether a port-group-level policy is overriding the switch-level policy.
Outbound Throughput Is Lower Than Expected
- Compare Average Bandwidth, Peak Bandwidth, and Burst Size with application requirements.
- Check for a more restrictive port-group override.
- Confirm that the limitation is intentional.
- Distinguish policy throttling from congestion or capacity limits on the physical uplink.
Exam-Relevant Notes
- Traffic shaping is disabled by default.
- Average Bandwidth and Peak Bandwidth are measured in Kbps.
- Burst Size is measured in KB.
- Peak Bandwidth cannot be lower than Average Bandwidth.
- Standard virtual switch traffic shaping is outbound-only.
- A port-group traffic shaping policy overrides the policy on its parent standard virtual switch.
For the complete configuration topic, use Switch Traffic Shaping Policies.