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vSAN Multicast performance test fails (2135495)

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  • The vSAN (formerly known as Virtual SAN) Multicast performance test fails showing a received bandwidth of 0.00 MB/s. This can be seen by running this RVC command at the cluster level: 0

  • Running the Proactive test on the Web client also shows it as Failed for certain hosts in the cluster. The list of hosts will not include the host from which  the test is initiated.
  • Running the tcpdump command shows each host receiving multicast traffic from each host in the cluster.


To work around the failure of vSAN Multicast performance test, create a private network on 2 ESXi hosts in the cluster, set a mulitcast group address in that network, and then monitor the results using iperf.


This is a known issue affecting the vSAN Health plugin for vSAN 6.1/6.2.

Note: In this example the vmk2 interface is set up on a private network 192.168.0.*

: This test should not be run in a production environment. This should be tested before any production virtual machine is added to the vSAN cluster. 

To work around the issue and test the multicast performance, you need to create a private network on 2 ESXi hosts in the cluster, set a mulitcast group address in that network, and then monitor the results using iperf.

To run the test:
  1. Manually create a private network on two  hosts and set the static IPs as and
  2. On each host, run this command to check the current routing table:

    esxcli network ip route ipv4 list

    At this point the routing table looks similar to:

    default  vmk0       DHCP        vmk0       MANUAL        vmk2       MANUAL

  3. Create a temporary multicast group within the private network to test performance. On each host, bind the multicast group address to this network using this command: 

    esxcli network ip route ipv4 add -n -g

    Where is the vSAN Network and is the default multicast network used for vSAN.

    Check the routing table again, it should look similar to:

    default  vmk0       DHCP        vmk0       MANUAL        vmk2       MANUAL    vmk2       MANUAL

  4. Run iperf server and client to test that the new multicast group is working:

    On server side (

    [root@sc-rdops-vm02-dhcp-38-134:/usr/lib/vmware/vsan/bin] ./iperf.copy -y C -s -B -u -i 1

    Note: The iperf.copy file is not present in a newly provisioned ESXi host, it is created by the vSAN health plug-in at first start up.

    On client side (

    [root@sc-rdops-vm02-dhcp-58-79:/usr/lib/vmware/vsan/bin] ./iperf -y C -c -u -w 1M -b 1M -t 10 -i 5

  5. Run the multicast performance test from the vSAN Health, monitor and note the results.
  6. Remove the temporary  multicast group route using this command:

    esxcli network ip route ipv4 remove -n -g

Additional Information

This issue is mentioned in the VMware Virtual SAN 6.1 Release Notes.
For more details on the multicast performance test, see section 7.2 in the Virtual SAN Health Check Plug-in Guide.


vSAN Multicast performance test

See Also

Update History

02/03/2017 - Added vSAN 6.5 to Products.

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.


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