While setting up a VEEAM Back-up & Replication infrastructure on VMware vSphere/ESXi hypervisors I ran into network performance issues.

VEEAM proxy’s (Hot-Add Mode) were connected to Port Groups/vSwitch holding multiple physical aggregated 1Gbps vmNIC’s. Since I had 4 physical vmNIC’s combined I should’ve roughly gotten about 480MBps , yet speeds kept below 120MBps.

VMware analytics pointed out that only 1 out of 4 physical NIC’s in the Link Aggregation Group (LAG) was being used for outbound traffic. Seems the load-balancing algorithm was causing this, being L2 IP Hash method (VMware KB1004048).

In the above example the combination of the Source and Target IP’s were causing this behavior. Which meant modifying one of the IP’s resulted into VMware sending out traffic over multiple NIC’s.

To avoid these situations in future cluster set-ups, I’ve modified an Excel Spreadsheet calculator to predict these outputs by modifying IP designs.

Download Excel Spreadsheet Calculator

VMware Link Aggregation (L2) Output Interface Calculator.xlsx