The Equal Cost Multi-Path Routing is a new feature available on SonicOS 6.5 and later.
This feature enhances SonicWall routing and allows for the ability to load balance traffic across equal cost routes for a given destination. You can now configure up to four equal cost routes for a given destination and you can use both static and dynamic routes.
Together with Load Balancing, this feature will also provide route redundancy.
Additional information to keep in mind:
Each gateway within a same ECMP entry has same chance to be selected as the next-hop. E.g, if there are 4 GWs in an ECMP entry, generally in production each gateway will take 25% connections/traffics.
Selection happens on new connection only. For packets belonging to an existed cache, they will use the gateway from the cache.
If one gateway is down at runtime, it will be excluded from the selection until it’s back again. E.g, a gateway down is determined by egress interface link status connected to the gateway.
The Equal Cost Multi-Path Routing can be easily configured from the static route configuration.
Login to the firewall and navigate to the Manage tab
Click Network | Routing and add a Static Route
Configure it as needed and select Multi-Path Route
Specify the number of gateways you want to use
Select the equal cost gateways and interfaces
Now the traffic will be equally passed across the gateways.
NOTE: This feature can only be used with custom routes. For Default Static Routes, you can use the WAN Load Balancing feature.