Re: [lwip-users] ping with packet size greater than MSS

[Bernhard 'Gustl' Bauer]

address@hidden schrieb:
> Bernhard 'Gustl' Bauer wrote:
> > Hi,
> >
> > how does LWIP treat these pings?
> >   
>
> Incoming or outgoing? For incoming, IP_REASSEMBLY must be set to 1. For 
> outgoing, IP_FRAG must be set to 1. If so, the pings should be handled 
> correctly. If not, some error counter in LWIP_STATS should be increased.
>
> What Kieran remembered was a problem where the incoming ping packet did 
> not have enough memory to be re-used as an outgoing packet (which is the 
> default implementation of ping). However, since 
> LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN defaults to 1 and is not exposed in 
> opt.h, there should be no need to change it.


IP_REASSEMBLY and IP_FRAG are set to 1 by default. I did not change 
this. I cannot find LWIP_ICMP_ECHO_CHECK_INPUT_PBUF_LEN!! But I'm using 
some 1.3 version. How can I verify which one? init.h contains no version 
info.

My TCP_MSS is 1460. A ping -s1472 does work, but a ping -s1473 does not! 
 A large ping can even crash my program.