Alan Cox wrote:
> > Machine is web serwer with reather big traffic. Why there is
> > so much connections in TIME_WAIT state ?
> Its quite normal. A tiny fragment of a TCP session has to remain for 2 minutes
> after use at least at one end of a TCP connection to avoid corruption.
"2 mintues" may be how the Linux kernel does it, but it's not the way
TCP says it should be done.
TIME_WAIT should last for 2*MSL (maximum segment lifetime). I know it's
hard to calculate MSL, and if you make up a hard-coded value it has to
be long enough for the slowest connections. It could be that FreeBSD
4.0 does do this calculation. If we can calculate semi-accurate MSLs
for each connection, TIME_WAIT states would be minimized.
Even over a slow Internet link, the MSL can't be much longer than 10
seconds or so. By then a segment has either been TTL'd out, or is
lost. I don't buy "MSL == 1 minute" at all.
-- = Warren Young, maintainer of the Winsock Programmer's FAQ at: = http://www.cyberport.com/~tangent/programming/winsock/ = = ICBM Address: 36.8274040 N, 108.0204086 W, alt. 1714m
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This archive was generated by hypermail 2b29 : Fri Jun 23 2000 - 21:00:22 EST