What is multihoming
Multi-homing is a function that can distribute the load over multiple routes to the same destination.
You can connect to multiple ISPs at the same time and distribute packets according to the line speed to each ISP. Provides fault tolerance compared to relying on a single ISP for connectivity.
If the line goes down, the packets can be sent out through another ISP.
You can also specify the outgoing ISP based on the source IP address (network address).
In order to use the multi-homing function, it is necessary to perform address conversion by IP masquerade for each interface connected to the ISP.
Some applications are incompatible with multihoming. For example, it is incompatible with FTP passive mode.
If the load is distributed and the interface to send packets is assigned to each packet, the result of address translation by IP masquerade will be different for each interface.
Therefore, it is not compatible with applications that communicate while linking multiple sessions because the source IP address is different.