Enabling vSphere Distributed Switch health check in the vSphere Web Client

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

This article provides information on and steps to enable the vSphere Distributed Switch health check in the vSphere Web Client. Also follow these steps to disable the vDS Health Check.

Environment

VMware vSphere ESXi 

Resolution

The network configuration for the vSphere infrastructure is a two-step process, whereby users must configure the physical network switches to which the vSphere host is connected and then configure the VDS. There are key network parameters, such as VLAN, network adapter teaming, and MTU, that should be configured properly on physical and virtual switches.

However, there are occasions when there are network connectivity issues in the user environment because these parameters are not configured properly. Network connectivity issues caused by configuration errors are often difficult to identify. This particularly is the case in an organization where the network administrators and vSphere administrators take management ownership of physical network switches and vSphere hosts respectively. In earlier versions of vSphere, there were no tools available that could help resolve such misconfigurations across the physical and virtual switches.

These are some of the common configuration errors that health check identifies:

• Mismatched VLAN trunks between a vSphere distributed switch and physical switch.
• Mismatched MTU settings between physical network adapters, distributed switches, and physical switch ports.
• Mismatched virtual switch teaming policies for the physical switch port-channel settings.

The network health check in vSphere monitors the following three network parameters at regular intervals:

• VLAN: Checks whether vSphere distributed switch VLAN settings match trunk port configuration on the adjacent physical switch ports.
• MTU: Checks whether the physical access switch port MTU setting based on per VLAN matches the vSphere distributed switch MTU setting.
• Network adapter teaming: Checks whether the physical access switch ports EtherChannel setting matches the distributed switch distributed port group IP Hash teaming policy settings.

The default interval for performing the configuration check is one minute. At this regular interval, layer 2 Ethernet probing packets are sent and received across the physical uplink interfaces of the VDS. Depending on the configuration of the network device, which is connected directly to the VDS through the physical uplink interfaces, REQ and ACK packets are received or dropped. When packets are dropped, it indicates that there is a configuration issue and a warning is displayed in the vSphere Web Client view.

For the network health check feature to work, ensure that these requirements are met:

• VLAN and MTU check – There must be at least two physical uplinks connected to the VDS.
• Teaming policy check – There must be at least two active uplinks in the teaming and at least two hosts in
  the VDS.

Enabling or disabling the vSphere Distributed Switch health check in the vSphere Web Client

1. Browse to a vSphere distributed switch in the vSphere Web Client.
2. Click the Configure tab.
3. Under Settings select Health Check.
4. To enable or disable health check, click Edit.
5. Select from the dropdown to enable or disable health check options.
   
   The options include:
6. • VLAN and MTU: Reports the status of distributed uplink ports and VLAN ranges
   • Teaming and Failover: Checks for any configuration mismatch between ESXi and the physical switch used in the teaming policy.
      
7. Click OK.

Viewing the vSphere Distributed Switch health check information

Note: After enabling health check, you can view the vSphere distributed switch health check information in the vSphere Web Client.

1. Browse to a vSphere distributed switch in the vSphere Web Client.
2. Click the Monitor tab and click Health.
3. In the Health Status Details section, click one of these tab to view the health status:
    
   • VLAN
   • MTU
   • Teaming and Failover

Additional Information

Depending on the options that you select, the vSphere Distributed Switch Health Check can generate a significant number of MAC addresses for testing teaming policy, MTU size, VLAN configuration, resulting in extra network traffic. For more information, see vDS Health Check reports unsupported VLANs for MTU and VLAN

After you disable vSphere Distributed Switch Health Check, the generated MAC addresses age out of your physical network environment according to your network policy.

Impact/Risks:
Review the vDS health Check limitations, which can be found in the "Additional Information" section of vDS Health Check reports unsupported VLANs for MTU and VLAN.

Depending on the options that you select, the vSphere Distributed Switch Health Check can generate a significant number of MAC addresses for testing teaming policy, MTU size, VLAN configuration, resulting in extra network traffic.
Ensure the number of MAC addresses to be generated by the health check will be less than the size of the physical switch(es) MAC table. Otherwise there is a risk that the switches will run out of memory, with subsequent network connectivity failures. After you disable vSphere Distributed Switch Health Check, the generated MAC addresses age out of your physical network environment according to your network policy.