"Kieran Mansley" <[email protected]> wrote:
On Thu, 2009-06-18 at 11:00 +0200, Lou Cypher wrote:
Simon Goldsmith <[email protected]> wrote:
> What you are seeing is that the PCBs are remaining in a wait-state for
> some time. This is to prevent packets from the old (closed) connection
> being possibly accept on a new connection. The port stays known to the
> stack and it can send RST packets when new packets for that port are
> received. However, while these PCBs are not yet freed, they are *not*
> in
> an active state any more, thus tcp_slowtmr is correct.
Everything is clear, does make sense to me.
How long can be "some time"? :)
2 * TCP_MSL
See tcp_slowtmr() where it handles the "TIME-WAIT" pcbs
For the default TCP_MSL, that would be 2 minutes.
One thing I don't understand about this discussion: the tcp_alloc() function
tries to allocate a new PCB, but if that fails, it tries killing a PCB in
the TIME_WAIT state (picking the oldest one), then it retries the
allocation.
This should mean that even if all PCBs are used, it will be possible to
start a new connection as long as at least one recent connection has closed
(and has got far enough through the FIN/ACK handshakes, but hasn't reached
the 2 * TCP_MSL timeout).
This code is similar in LWIP 1.2.0, 1.3.0 and CVS-head, and it works fine
for us using the raw API, but I haven't looked at implications for higher
level APIs.
What piece of information am I missing, and why isn't it working for Lou?
_______________________________________________
lwip-users mailing list
[email protected]
http://lists.nongnu.org/mailman/listinfo/lwip-users
