bandu wrote: > Hi, > > I'm a bit new to lwip. > > When I transfer data both side with network switch, it work fine. > > When I'm using hub, I can see avialable tcp_sndbuf going down to zero and > never coming back up to TCP_SND_BUF size. > > I'm checking tcp_sndbuf before tcp_write and I called tcp_output() > > When both TX and RX, I can see it happened more quickly than RX only. > > What would cause that tcp_sndbuf draining? i'm using lwip 1.3.0.
Using a hub will make no difference to lwIP itself. If there's any problem, it's at a lower layer. Are you sure the link is actually reliable? Are packets getting through? Are there retries? That's the most likely reason the send buffer is getting smaller. The only way a hub might affect what lwip sees at all is if your low-level ethernet driver is setting the ethernet MAC to promiscuous mode. It shouldn't be. Although even then, lwIP should happily be dropping the packets - I wouldn't expect it to cause the problem you see. If your driver was using promiscuous mode, all I would expect is that your software has to do more processing before discarding the packet. 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 _______________________________________________ lwip-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/lwip-users
