Re: [lwip-users] Netifs routing

[Sergio R. Caprile]

Do you actually have a VM running lwIP ???
I don't think so, you probably have a VM running an OS and lwIP running
inside that. Do you ?
This is important, because the lwIP "netif" low-level driver you are
using depends on the OS you have underneath.

So, if your scenario is as I guess, then follow me, otherwise, I'm
sorry, please enlighten me on how you have lwIP running by itself on a VM.

VM-lwip:
        eth0:

        lwIP:
                netif-0 -> TUN/TAP -> eth0
                netif-1 -> tty0

VM-0 shares an ethernet with VM-lwip and lwIP in netif-0
VM-1 connects to lwIP in netif-1

Your first problem is that, unless you configure it as a bridge, you do
it properly, and it works OK, the most probable scenario you have is
that netif-0 and eth0 belong to different networks, the TUN/TAP
interface acts as a router interface and VM-lwip needs to be configured
to route (IP-forward if it is a Linux box) and BOTH lwIP and VM-0 need
no know VM-lwip as a router, default gateway is the easiest.

Since you say "it works", you probably managed to have it right. Please
write down your network configuration, which subnets you have on every
interface and if you have set default gateways.


Regarding PPP... your lwIP should have got its IP address and gateway
from VM-1 acting as a PPP server... or did you statically configure both
? What did you do ?
If you know lwIP processes the PPP packet, then you should be able to
tell why it sends it to the other interface by following it.
If you have a default gateway to the ethernet, it will send packets to
that one by default. There are hooks to do some sort of routing if you
need it, but I can't help further.