We have briefly talked about NIC teaming in VMware vSphere before, and why it is such a powerful tool in our vSphere aresenal. If you need a quick refresher, NIC teaming in VMware vSphere is important for both redundancy and load balancing. Now, we are going to simplify NIC teaming to the most basic form in vSphere, the default settings. I call it simple since we do not need to change anything out of the box.
Ready to take a look at how this works?
Route Based on Originating Virtual Port
The default load balancing algorithm is called “Route based on originating virtual port”. This simply means vSphere will assign the virtual ports of the virtual machines to the next uplink, as illustrated in the following diagram. When I say uplink, I am talking about the physical network port on the ESXi host which is connected to a software based virtual switch.
VM A connects to uplink 1, VM B connects to uplink 2, and VM C once again connects to uplink 1 since we have begun to cycle through the list of uplink ports after we have reached the end. If we had a VM D, it would connect to uplink 2.
This is great, because virtual machines will be evenly distributed across our available uplink ports. This is not so great, because because this simple load balancing method has no idea bout the utilization of the uplink ports.
vSphere Enterprise Plus Saves the Day
If you are a vSphere Enterprise Plus customer, you are in luck! As we mentioned previously, vSphere Enterprise Plus has an additional load balancing algorithm called “Route based on physical NIC load”, commonly referred to as LBT or Load Based Teaming. LBT is available when using a distributed virtual switch. It is also quite simple because it starts out working the same way as the default load balancing algorithm. Remember what we said the big problem was with that? LBT solves this by becoming aware of the load on each uplink port. If an uplink port reaches 75% utilization over a 30 second period, the busy VM is moved to another uplink.
While using LBT does require minimal configuration on your virtual switch (simply selecting “Route based on phyiscal NIC load”), it is still quite simple since it provides load balancing without needing to configure any upstream components. Once it is selected, virtual machines will be evenly balanced across your uplink ports, and VMs will be moved to another uplink port if they get busy.
If you are still are trying to decide the best way to configure your vSphere networking, be sure to take a take a moment to think about Making vSphere Networking Design Choices.