Re: [lwip-users] eCos - PPP - TCP - LwIP

[Jonathan Larmour]

Ashish Anand wrote:
> Jonathan Larmour wrote:
> > Ashish Anand wrote:
> > > I turned on debugging. This is what I get when I try to telnet to the
> > > board
> > > (192.168.1.4) from 192.168.1.3...... (0x401a8c0 is 192.168.1.4, the
> > > board):
> > >
> > > ip_input: iphdr->dest 0xfb0000e0 netif->ip_addr 0x401a8c0 (0xe0, 0x1a8c0,
> > > 0xfb00000)ip_input: iphdr->dest 0xfb0000e0 netif->ip_addr 0x100007f
> > > (0xe0,
> > > 0x7f, 0xfb000000)
> > > ip_input: packet not for us.
> > > ip_forward: not bouncing packets back on incoming interface.
> > >
> > >
> > > So basically, the data link layer (PPP) is up. But I am not able to do
> > > much
> > > at the network layer (IP/ICMP).
> > Try debugging the netif layer. See if the PPP layer does set the IP
> > address 
> > for the ppp interface, and if so, to what.
>
> I have done that. The board is being assigned the correct IP as specified by
> my PPP Server. I am able to printf the board IP, the server IP and netmask
> also. So it's not a data link layer issue probably.

Sorry, yes, if I had read your earlier output more carefully I'd have seen 
that. The destination address in the IP header field above is 224.0.0.251

That's a multicast address (see 
http://en.wikipedia.org/wiki/Multicast_address ). In fact specifically that 
is Rendezvous/multicastDNS. Are you sure this only happens at the point you 
do the telnet? I suspect in fact this packet comes from some other process 
on your host which is sending them, and it's sending it to all connected 
interfaces including ppp.

If so, then that means IP connectivity in general is working as far as the 
target is concerned, and the problem may in fact be the host. Perhaps the 
routing tables? Perhaps using tcpdump or ethereal on the various interfaces 
on the host may show you where the packets are going, at the point you 
actually initiate the telnet.

Jifl
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