Configure Network Interface for Witness Traffic

Virtual SAN data traffic requires a low-latency, high-bandwidth link. Witness traffic can use a high-latency, low-bandwidth and routable link. To separate data traffic from witness traffic, you can configure a dedicated VMkernel network adapter for Virtual SAN witness traffic.

You can separate data traffic from witness traffic in supported stretched cluster configurations. The VMkernel adapter used for Virtual SAN data traffic and the VMkernel adapter used for witness traffic must be connected to the same physical switch.

You can add support for a direct network cross-connection to carry Virtual SAN data traffic in a two-host Virtual SAN stretched cluster. You can configure a separate network connection for witness traffic. On each data host in the cluster, configure the management VMkernel network adapter to also carry witness traffic. Do not configure the witness traffic type on the witness host.

Prerequisites

• Verify that the data site to witness traffic connection has a minimum bandwidth of 100 MBps and a latency of less than 200 ms RTT.
• Verify that Virtual SAN traffic can be carried over a direct Ethernet cable connection with a speed of 10 GBps.
• Verify that data traffic and witness traffic use the same IP version.

Procedure

1. Open an SSH connection to the ESXi host.
2. Use the esxcli network ip interface list command to determine which VMkernel network adapter is used for management traffic.
   For example:

   esxcli network  ip interface list
   vmk0
      Name: vmk0
      MAC Address: e4:11:5b:11:8c:16
      Enabled: true
      Portset: vSwitch0
      Portgroup: Management Network
      Netstack Instance: defaultTcpipStack
      VDS Name: N/A
      VDS UUID: N/A
      VDS Port: N/A
      VDS Connection: -1
      Opaque Network ID: N/A
      Opaque Network Type: N/A
      External ID: N/A
      MTU: 1500
      TSO MSS: 65535
      Port ID: 33554437
   
   vmk1
      Name: vmk1
      MAC Address: 00:50:56:6a:3a:74
      Enabled: true
      Portset: vSwitch1
      Portgroup: vsandata
      Netstack Instance: defaultTcpipStack
     VDS Name: N/A
      VDS UUID: N/A
      VDS Port: N/A
      VDS Connection: -1
      Opaque Network ID: N/A
      Opaque Network Type: N/A
      External ID: N/A
      MTU: 9000
      TSO MSS: 65535
      Port ID: 50331660
   

3. Use the esxcli vsan network ip set command to configure the management VMkernel network adapter to support witness traffic.

   esxcli vsan network ip set -i vmkx -T=witness 

4. Use the esxcli vsan network list command to verify the new network configuration.
   For example:

   esxcli vsan network list
   Interface
      VmkNic Name: vmk0
      IP Protocol: IP
      Interface UUID: 8cf3ec57-c9ea-148b-56e1-a0369f56dcc0
      Agent Group Multicast Address: 224.2.3.4
      Agent Group IPv6 Multicast Address: ff19::2:3:4
      Agent Group Multicast Port: 23451
      Master Group Multicast Address: 224.1.2.3
      Master Group IPv6 Multicast Address: ff19::1:2:3
      Master Group Multicast Port: 12345
      Host Unicast Channel Bound Port: 12321
      Multicast TTL: 5
      Traffic Type: witness
   
   Interface
      VmkNic Name: vmk1
      IP Protocol: IP
      Interface UUID: 6df3ec57-4fb6-5722-da3d-a0369f56dcc0
      Agent Group Multicast Address: 224.2.3.4
      Agent Group IPv6 Multicast Address: ff19::2:3:4
      Agent Group Multicast Port: 23451
      Master Group Multicast Address: 224.1.2.3
      Master Group IPv6 Multicast Address: ff19::1:2:3
      Master Group Multicast Port: 12345
      Host Unicast Channel Bound Port: 12321
      Multicast TTL: 5
      Traffic Type: vsan
   

Results

In the vSphere Web Client, the management VMkernel network interface is not selected for Virtual SAN traffic. Do not re-enable the interface in the vSphere Web Client.