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 the
    Network Prevent for Email
    Server VIP.
  • The load balancer rewrites the destination address of each packet in each SMTP session as the IP address of one of the
    Network Prevent for Email
    Servers.
  • The
    Network Prevent for Email
    Server creates a connection to the MTA VIP (specified in the
    RequestProcesser.NextMTA
    field in the advanced settings of the
    Network Prevent for Email
    Server).
  • 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.