[lwip-users] Re: [lwip] lwip [linux]

[Adam Dunkels]

Hi!

On Thursday 08 November 2001 15.26, you wrote:
> I tried to run the latest lwip-0.4.1 on a linux machine (2.4 kernel).To
> test lwip (unixsim), I found that there are two executables that I can use.
> Simrouter to run first a unix server. Then simnode the unix client.
[...]
> To my understanding,
> When a packet is received on the network side of the TapX, it is read by
> the Simrouter from the character side of the TapX.
> If the packet is destined for the interfaces of the Simrouter, then the
> response is sent back through the network side of the TapX to the Linux
> side. If the packet is destined for the Simnode then the Simrouter sends
> the packet to the Simnode. The Simnode sends the response over the socket
> connection to the Simrouter which inturn sends to the Linux side over the
> network side of the TapX.

You are absolutely correct, the problem is with version 0.4.1 of lwIP which 
doesn't work very well on Linux. It appears as version 0.4.2 works better 
with Linux, so you could try with that instead.

The problem is that the wrong argument was given to the "ifconfig" command 
when the tap0 interface is configured. In Linux 2.2, the tap interface was 
configured as a point-to-point link with two IP addresses, but in Linux 2.4 
the tap interface works as an emulated Ethernet. Since the Linux adaptation 
of lwIP/unixsim was written and tested for Linux 2.2, things broke with 2.4 
and the tap interface was configured to have the same IP address as simrouter 
(192.168.0.2). 

You might also try running the single binary "simhost", which is one instance 
of lwIP running with IP address 192.168.0.2.

Cheers,

/adam
-- 
Adam Dunkels <address@hidden>
http://www.sics.se/~adam
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