It is merely another approach on vlan tags. The two interfaces come from a device driver, that splits incoming traffic based on vlan tags and tags outgoing traffic accordingly.
I would argue that this is a common technique if you do not want to put your faith in routing.
I am aware, there are more lines of code to add to achieve this design throughout the project and I am willing to supply further patches, however I do not see, how this adds immoderate complexity.
>While I understand your setup, I just do not see it as a common use case to
>justify adding code for it.
>Since lwip is open source, you're of course free to do this in your local
>sources.
>
>Simon
>
>> Hello Simon,
>> in our case the routing mechanism can be ambiguous.
>>
>> We have several devices in the internal network that have static ips.
>> However the netmask/ip addresses of the external net are not known, it is
>> likely they overlap.
>>
>> There are other ways to solve this, but I think binding pcbs to netifs is
>> the clean one and can be beneficial in other setups with more than one
>> interface.
>>
>> Also, as a user, you can route one time in the initialization of a pcb,
>> bind it accordingly and thus save many calls to ip_route().
>>