You can isolate the network traffic of vSphere Replication from all other traffic in a data center's network.
Isolating the replication traffic helps you ensure that sensitive information is not routed to the wrong destination, and helps you enhance the network performance in the data center, because the traffic that vSphere Replication generates does not impact other types of traffic. You isolate the network traffic to the vSphere Replication Server by dedicating a VMKernel NIC on each ESXi host on the primary site that sends data to the vSphere Replication Server. See Set Up a VMkernel Adapter for vSphere Replication Traffic on a Source Host.
If you are using a distributed network switch, you can take advantage of the vSphere Network I/O Control feature to set limits or shares for incoming and outgoing replication traffic on each ESXi host. The feature allows you to manage the network resources that vSphere Replication uses.
- Management traffic between vSphere Replication Management Server and vSphere Replication Server.
- Replication traffic from the source ESXi hosts to the vSphere Replication Server.
- Traffic between vCenter Server and vSphere Replication Management Server.
In the combined vSphere Replication appliance, the IP address that is used for management traffic between the vSphere Replication Management Server and vSphere Replication Server is localhost 127.0.0.1. Therefore, you do not need to add network adapters for this type of traffic.
When the vSphere Replication Management Server and the vSphere Replication Server run on separate appliances, you can specify a non-localhost IP address to be used by the vSphere Replication Management Server.
In addition you must configure static routes on each ESXi host at the source site with how to communicate with the target site and the reverse. See http://kb.vmware.com/kb/2001426. For replications to flow in the opposite direction, you must configure reverse routes on the target site ESXi hosts.