This is due to pcbs being placed in a TIME_WAIT state; i.e. when you close a connection they're not really freed yet, they're hanging around waiting for enough time to pass to make sure no stray packets come in and screw up a future connection. Note that the default 'enough time' is like two hours, so an automatically refreshing web page will eat up pcbs very quickly. (This is TCP standard behavior as defined in the RFQs, though it makes little sense in today's high-speed networks.)
Even though the error count gets incremented, lwIP will (upon finding no free pcbs) allocate a pcb from the TIME_WAIT list and use it, so this may not actually be a problem for your implementation. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jonathan Larmour Sent: Wednesday, August 27, 2008 8:48 AM To: Mailing list for lwIP users Subject: Re: [lwip-users] Lwip 1.3.0 Running out of TCP PCB's fast B B wrote: > Now when i connect to the devices webpage, the number of used tcp_pcb > goes up. > And after 10 page hits, the stats say the following: > > TCP_PCB avail: 10 > TCP_PCB used: 10 > TCP_PCB max: 10 > TCP_PCB err: 5 > TCP_PCB_LISTEN avail: 3 > TCP_PCB_LISTEN used: 1 > TCP_PCB_LISTEN max: 1 > TCP_PCB_LISTEN err: 0 > > > i've thought that "TCP_PCB used" should be 2, one for each connection. > But that is not the case. > Is there anything i can do to avoid this situation ? > > here is my code for my webserver task: > [snip] > > Should the above cause this behaviour ? I didn't notice anything incorrect in what you posted. But does handleDHCP() allocate any PCBs? 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 _______________________________________________ lwip-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/lwip-users
