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Re: [lwip-users] UDP packet sending problem

From: patrick Deflandre
Subject: Re: [lwip-users] UDP packet sending problem
Date: Tue, 30 Jun 2009 12:08:15 +0200

2009/6/29 Kieran Mansley <address@hidden>
On Mon, 2009-06-29 at 15:41 +0200, patrick Deflandre wrote:

> None of the packet are compliant with the tftp protocol. This will
> surely make wireshark in trouble when checking an expected checksum...

No: the UDP checksum is independent of the next protocol layer, and so
won't care if the TFTP bit is correct or not.

I was wrong, Thank for the precision.

I notice that in the udp_echo.trace.txt there is the following:

<LF>find_entry: selecting empty entry 1
<LF>etharp_request: sending ARP request.etharp_raw: sending raw ARP
packet.etharp_query: queued packet 215bf0 on ARP entry 1

This is odd for two reasons: (i) it should already have an entry for the
PC's MAC address as it's updated that entry lots already from the other
ARP requests seen on the network earlier; and (ii) the packet it sends
is not an ARP request for the PC's MAC, but a gratuitous ARP of its own
MAC.  I think there is definitely something going wrong here.

Do you have ARP_QUEUEING on?

Yes, I have ARP_QUEUEING on. But I did not bother until now. Is this good or not ? Should I change this value ?

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