Multipath rules control uplink balancing (with the uplink balancing function you can combine more than one Internet uplink, either for having backup uplinks available or for using load balancing among multiple uplinks).
The multipath rules are applied to the active interfaces on the 'Uplink balancing' tab of the WebAdmin when there is more than one interface to balance traffic between. Without multipath rules, all services are balanced by source, i.e., all traffic coming from one source uses the same interface, whereas traffic from another source can be sent to another interface. Multipath rules allow you to change this default interface persistence.
With the release of Sophos UTM version 9.1 it is possible to set multipath rules as 'sticky' which enforces a multipath rule at all times (e.g, a SMTP 'sticky' multipath rule would ensure that SMTP traffic is always routed over a specific IP address, even if the interface is down).
This article explains how to make a multipath rule sticky when being created.
Known to apply to the following Sophos product(s) and version(s) Sophos UTM
Operating systems UTM 9.1 or higher
The multipath rule will be applied even if there is a problem detected with the interface.
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