Re: [lwip-users] Limited packet size on netconn_recv

[address@hidden]

Peter Murphy wrote:

I’m developing a FTP server to run under lwip and freeRTOS. I can send directory info and files over the FTP data port but when I go to receive a file I get a 20 second delay. WireShark shows the first packet is sent milli-seconds after the ‘150 Opening connection’ message is sent but lwip ignores this packet until the client resends the data with a shorter packet length. The first packet sent is 1460 and the following two retransmits are 1460. The third and subsequent packets are 536 in length. Lwip picks up these short packets and returns them to my thread but only after the delay.

That really does look strange. Unless the netif driver discards the bigger packets, there's no reason lwIP should reject these (having set TCP_MSS to 1460). It might help to turn on debug output or have a look at the stats to see at which point packets are rejected (if they are received at all). Also, a wireshark trace might show up something?

Simon