Kerio Tech Firewall6 - Manual (Page 94)

Chapter 7 Traffic Policy
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Setting of NAT in the rule for email services is shown in figure 7.31 . It is recommended to
allow use of a back-up link for case that the reserved link fails. Otherwise, email services will
be unavailable when the connection fails.
Figure 7.31 Policy routing — setting NAT for a reserved link
Let us suppose that the mailserver provides also Webmail and CalDAV services which use
HTTP(s) protocol. Adding these protocols in the first rule would make all web traffic routed
through the reserved link. To reach the desired goal, the rule can be modified by reserving the
link for traffic with a specific server — see figure 7.32 .
Figure 7.32 Policy routing — a link reserved for a specific server
Note: In the second rule, automatic interface selection is used. This means that the Internet
4Mbit link is also used for network traffic load balancing. Email traffic is certainly still re-
spected and has higher priority on the link reserved by the first rule. This means that total
load will be efficiently balanced between both links all the time.
If you need to reserve a link only for a specific traffic (i.e. route other traffic through othe
links), go toConfiguration → Interfaces and set the speed of the link to 0 Mbit/s. In this case
the link will not be used for load balancing. Only traffic specified in corresponding traffic rules
will be routed through it.