Prior to vSphere 6, the replication traffic was sent and received using the management interfaces of ESXi and VRA appliances. With vSphere 6 it is possible to send the replication traffic over a separate dedicated interface.
By default, the vSphere Replication appliance has one VM network adapter that is used for various traffic types.
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Management traffic between vSphere Replication Management Server and vSphere Replication Server.
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Replication traffic from the source ESXi hosts to the vSphere Replication Server.
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Traffic between vCenter Server and vSphere Replication Management Server.
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NFC (Network File Copy) traffic which is used to copy VM replication data from the vSphere Replication Server appliance at the target site to the destination datastores.
VR Traffic Flow
We will use below image for understanding the flow of replication traffic
Typically these are the sequence of events that take places when a VM is configured for replication and initial sync has completed:
- As data is written to VM disks, the writes pass through the vSCSI filter on the host where the VM is running
- The vSCSI filter monitors all I/O to the VMs disks and tracks those changes.