Re: [lwip-users] [lwip]Stack crashing with huge ICMP packets

[Kieran Mansley]

On 24 Jan 2012, at 11:10, Dennis Borgmann wrote:

> Hi lwIP-users!
> 
> I am sorry, if this mail seems to be "old stuff" for most of you, but I could 
> not find any detailed information about what I am facing here.
> 
> I have lwIP 1.3.2 running combined with FreeRTOS on an AVR32UC3A0512. It 
> works fine, but as soon as I start a ping with packetsize 2000(or something 
> similar), the stack seems to crash - meaning, I can't reach the device via IP 
> anymore. As long as I stay below 1536, everything just runs fine.

I think it could just be that the ping code in that release assumes that the 
whole datagram will fit in a single packet.  When you exceed the MTU the 
datagram will be fragmented and I doubt the code has been written to cope with 
that.

> What could be the option, that I'd have to increase in order to get a 
> "stable" lwIP-stack with packets bigger than 1536(let's say even 65000...)?

I would try and see if (i) the more recent versions of lwIP do what you want, 
or (ii) if the problem is just with ICMP; I would hope that large UDP datagrams 
are handled correctly for example.

Kieran