Re: [lwip-devel] How to understand TCP_SND_BUF

[Simon Goldschmidt]

narke <address@hidden> wrote:

> I found the value of TCP_SND_BUF was assigned directly to snd_buf
> attribute when a new pcb was allocated.   Then I lost understanding
> why this variable should be used.
> 
> It's different with snd_wnd,  which is dynamically changed after a new
> value is advertised from the peer end.
> It's also has nothing to do with memory space of sending pbufs, which
> is determined by MEM_SIZE constant.

You got the point without noticing it: snd_buf does limit the memory space of 
sending pbufs, not for the whole stack but for single connections. It is used 
to prevent one connection from using up all memory.

Simon