Re: [lwip-users] TCP checksum error for big sized packets on lwip 1.3.0

[Jonathan Larmour]

Muhamad Ikhwan Ismail wrote:
>          
> Hi,
> 
> I found out the problem already. My driver was set up to transfer out
> one buffer per frame only (1520 bytes) since
> we want to spare processing power as much as we can and also due to the
> fact we have ample memory,
> and the 1.3.0 seems to chain the TCP packets to form frames(multiple
> buffers per frame). Is there any thing i can setup to force
> TCP packs 1520 bytes per buffer (pbufs) ?

lwIP can chain pbufs, but the total size (pbuf->tot_len) should always be
less than the MTU i.e. one packet. So if you get a pbuf chain to send, it
should still be less than 1520 bytes. If your driver can only send packet
data from contiguous memory, then you may need to copy the packet data into
a special large buffer. You will only be able to handle one packet at a
time then obviously.

Jifl
-- 
eCosCentric Limited      http://www.eCosCentric.com/     The eCos experts
Barnwell House, Barnwell Drive, Cambridge, UK.       Tel: +44 1223 245571
Registered in England and Wales: Reg No 4422071.
------["Si fractum non sit, noli id reficere"]------       Opinions==mine