The PPP interface is on serial port and without modem. I’d want to send the TCP/IP traffic from PPP interface to the Ethernet port with a static route. Is it possible?
It might be possible to forward the PPP traffic to a single destination IP on the Ethernet interface, but I think it would require low-level changes to the library.
What are you trying to accomplish? Setting up a Rabbit to share a PPP connection with multiple hosts on the Ethernet? Doing that would require NAT (network address translation) and tracking of connections between the Ethernet hosts and the PPP link.
In that case, it sounds like you just want to allow for TCP/IP communications on both interfaces. In that case, you don’t need to make any changes to the libraries. You can configure the Rabbit to establish a PPP connection and/or connect to an existing Ethernet network.