I was recently working with a customer to load balance their Exchange CAG front end with a NetScaler. The NetScaler was using two of the Gig interfaces – one connected to the LAN and the other connected to the DMZ. Although all the routing looked correct we were seeing intermediate packet loss on the DMZ interface. After speaking with Citrix about the issue it was determined that we needed to enable MAC based forwarding.
MAC based forwarding insures that the traffic is forwarded out the interface that is was received. Mac-based forwarding is also used to avoid multiple ARP/route lookups. I may be required when the NetScaler is connected to multiple stateful devices.
To enable MAC- based forwarding using the CLI interface use the following…
- enable ns mode mbf
To enable using the configuration utility-
Expand System and click the -&gt; Settings -&gt; Configure modes.

&nbsp;