pfSense

As of Plus 23.05.1 and CE 2.7.0, the OS supports multipath routing (i.e. ECMP).

However, outside of FRR, there isn't a way to configure it in the GUI yet.

There are a few hurdles to add this into the GUI and it's not clear what the best way to handle them might be, so it's open for debate:

• system_routes_edit.php disallows multiple entries for the same remote destination network -- would it be better to remove that limitation OR would it be better to allow the user to select multiple gateways on a single entry?
• Each destination+gateway pair can have a unique weight that controls the proportion of traffic which will use each route. The weight is not a property of the gateway but of the destination+gateway combination. This complicates the first point as allowing multi-select would then also need to have a way to set a weight for each gateway in the list. A rowhelper for the gateway+weight may work.
• in system.inc, the function delete_static_route() would need to account for the fact that there may be multiple gateways and delete only the entries which are no longer needed. The exact differences here would vary a bit depending on which method is used for the first point.
• It's not clear if/how the OS would ever take a gateway out of use if it's "down" -- that may mean we need to remove route entries for down gateways in some automated way, so a couple of the points in the original description are not viable.

Note: Even the same gateway used for multiple destination lands in a "nexthop" group based on each destination. The weight of each gateways inside each "group" determine the proportion of traffic that will take the gateway, with higher weights receiving more traffic. Equal weights get equal traffic. These groups and weights are visible in netstat -4OnW and netstat -6OnW

It's also unclear what effect, if any, this might have on OpenVPN instances with conflicting routing configurations (multiple instances with overlapping remote network lists, for example).