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[lwip-users] Routing error in lwip 1.3.0

From: Muhamad Ikhwan Ismail
Subject: [lwip-users] Routing error in lwip 1.3.0
Date: Thu, 10 Jul 2008 10:20:06 +0000


I have seen something weird with my implementation of 1.3.0. My test case looks like this.

1. Lwip appl task sends a telegram with string + a telegram no. lets call this packet packet  A.
2. It then receive from a java program an echo of the same string.
3. the application checks the no of the telegram and compare with the one it just sent. If equal then increments the no and send the next one. if not
it still send the next one, but report an error.
4. In case a telegram gone missing and the echo cycle disrupted, the java program will timeout (after 7 s) and resend the last packet it sent.

At the same time there is another task in the lwip device that sends a random packet (packet B) into the network every 10 s.

When the packet A and B were sent in a short amount of time between each other,following were observed.

1. Either the packet A was not sent at all. As if it is dropped from the stack. The task that sends packet A did the sendto correctly. The counter was incremented.
2, Or packet A was sent but to an address of (routing problem ?)

I have an example of the trace here. I have not debugged this problem yet, but I am just wondering if anyone heard of such a bug.
I am thankful for any tipps.

Thanks in advance.

M Ikhwan Ismail

Platform : PowerPC MPC852T
lwip : 1.3.0 (released)

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