Example of bi-directional load balancing
Load balancing with
Network Prevent for Email
Servers in forwarding mode shows an architecture that includes a bi-directional load balancer and a cluster of Network Prevent for Email
Servers operating in forwarding mode. After receiving and analyzing messages, the Network Prevent for Email
Servers forward them to a virtual IP address (VIP) specified in the advanced settings of each Network Prevent for Email
Server (in the RequestProcesser.NextMTA field).For details on configuring forwarding mode and on configuring the
Network Prevent for Email
Server in general, see the Symantec Data Loss Prevention
Help.Load balancing with Network Prevent for Email Servers in forwarding mode

Details about load balancing with
Network Prevent for Email
Servers in forwarding mode are as follows:- An upstream MTA creates an SMTP connection to theNetwork Prevent for EmailServer VIP.
- The load balancer rewrites the destination address of each packet in each SMTP session as the IP address of one of theNetwork Prevent for EmailServers.
- TheNetwork Prevent for EmailServer creates a connection to the MTA VIP (specified in theRequestProcesser.NextMTAfield in the advanced settings of theNetwork Prevent for EmailServer).
- The load balancer rewrites the destination address of each packet in the SMTP session as the IP address of one of the MTAs in the cluster.
Note that you can also operate the
Network Prevent for Email
Servers in reflecting mode with a bi-directional load balancer. One way to do this is to configure the load balancer to rewrite the source IP address to point to the second (return) VIP on the load balancer. The Network Prevent for Email
Servers would then reflect messages back to the return VIP.