vSphere 5.1 distributed switch health check helps identify and troubleshoot configuration errors in vSphere distributed switches.
vSphere runs regular health checks to examine certain settings on the distributed and physical switches to identify common errors in the networking configuration.
The following errors are common configuration errors that health check helps identify.
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.
Health check monitors the following:
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 jumbo frame setting based on per VLAN matches the vSphere distributed switch MTU setting.
Teaming policies. Checks whether the physical access switch ports EtherChannel setting matches the distributed switch distributed port group IPHash teaming policy settings.
Health check is limited to only the access switch port to which the distributed switch uplink connects.
For VLAN and MTU checks, you must have at least two link-up physical uplink NICs for the distributed switch.
For a teaming policy check, you must have at least two link-up physical uplink NICs and two hosts when applying the policy.
Depending on the options that you select, 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 Network health check feature limitations in vSphere 5.1 and 5.5 (2034795). After you disable vSphere Distributed Switch Health Check, the generated MAC addresses age out of your physical network environment according to your network policy.