Re: [lwip-users] LLDP Implementation for lwIP

[Sergio R. Caprile]

I sent my response before you answered to Simon, so I couldn't know your 
problem was in the output path without violating causality. I think some 
states penalize that... ;^)

When the stack needs to send a frame, it will call netif->output. That 
pointer is usually setup at the init function for the netif driver (see 
ethernetif_init()). My driver sets up etharp_output() for that, and I 
followed the guidelines in the wiki link I sent you, I suggest you 
follow that. I'm using bare metal, not an OS, and I don't remember if 
there is a constraint for this (it is for input stage).

Anyway, that will eventually call netif->linkoutput() which is what you 
probably want to use. Remember you are using bare Ethernet over your 
driver in your port; you are not (yet) using lwIP.