Re: [lwip-devel] Missing initialization somewhere?

[address@hidden]

Sergey Kubushyn wrote:
> Yes, I do have ARP_QUEUING turned on. Why it is not responding to other
> packets is simple -- netif (i.e. whatever this pointer points to) has it's
> UP flag bit set to zero. So for all practical purposes the interface is down
> and there is no way for the stack to send a packet out.
So does this mean the board responds to ICMP packets when the netif is 
down or is it up before that? A netif should be up for any communication 
other than DHCP or AutoIP negotiation.
> It doesn't look like it has something to do with ARPs but I might be wrong.
> The sequence is:
>
>         - Remote sends ARP for the MCU IP;
>         - MCU (lwIP) responds to ARP request properly;
>         - Remote sends SYN initiating 3-way TCP handshake;
>         - MCU sends ARP request for the remote IP (only once, not
>           for every SYN packet);
>         - Remote responds to that ARP;
>         - MCU generates a proper SYN/ACK packet and attempts to send it;
>         - That attempts fails in ip_route() because is_netif_up() tells the
>           netif is not up so there is no route out;
>         - After a timeout remote resends that initial SYN;
>         - MCU again generates a proper SYN/ACK packet and again attempts to
>           send it out with exactly the same result.
>         - That netif is down for ALL packets that is why nothing is going
>           out of the MCU. And there is nothing there to bring it back up.
At which point does the netif go down here?

Simon