Ensure vmnic uplink redundancy with Link State Tracking / Smart Links
A vSphere cluster is redundant in many aspects. The loss of one component may not lead to a loss of functionality. Therefore we are building RAID sets from multiple disk drives, have redundant controllers in our storages, have multiple paths, redundant LAN- and SAN-switches and multiple uplinks from a host to the physical network.
VMware vSphere uses multiple physical NICs to form a logical NIC in order to gain redundancy. This is crucial for kernelports, which are responsible for vMotion, Management Network, FT, iSCSI and Heartbeats.
But there are scenarios where all vmnics have physical uplink, but a path loss further downstream towards the core lets packets wander into a black hole.
We will now discuss some network architectures and how to work around the issue.