Re: [lwip-users] size of packet

[Kieran Mansley]

On Thu, 2010-03-04 at 12:58 +0100, Oscar F wrote:
> Hello everybody,
> 
> 
> My application use lwip 3.1. with AVR32 EVK1100
> 
> I have a important question. i want to send 50Kbytes, and use the
> fuctions send(....). 
> 
> why in the sniffer did i see the packet divided in several sizes.

Because lwIP is allowed to chop your sends up into packets in whatever
way is most convenient.  It might for example only have 100 bytes of
spare TCP window and decide to send a 100 byte packet to fill the window
instead of waiting for more space.  It might only have 100 bytes in the
send queue and so decide to send a 100 byte packet to use it up.  It
might not want the hassle of merging separate send calls together into
one packet.  And so on.  

> is there any possibility to put the packet full in the network?

To always only send MTU packets?  No, that's not really possible.

> What is the maximun size on the packet that i can use, because the
> library the function size, has a length 64 bit?

The maximum packet size is set by the network: it's the MTU of the
interface.

Kieran