nanog mailing list archives
Re: TCP time_wait and port exhaustion for servers
From: Owen DeLong <owen () delong com>
Date: Wed, 5 Dec 2012 11:31:14 -0800
On Dec 5, 2012, at 10:58 AM, William Herrin <bill () herrin us> wrote:
On Wed, Dec 5, 2012 at 12:09 PM, Ray Soucy <rps () maine edu> wrote:Like most web traffic, the majority of these connections open and close in under a second. When we get to a point that there is enough traffic from users behind the proxy to be generating over 500 new outgoing connections per second, sustained, we start having users experience an error where there are no local ports available to Squid to use since they're all tied up in a TIME_WAIT state. Here is an example of netstat totals on a box we're seeing the behavior on: 481947 TIME_WAITStupid question but how does 500 x 60 = 481947? To have that many connections in TIME_WAIT on a 60 second timer, you'd need more like 8000 connections per second, wouldn't you?
Isn't TIME_WAIT based on disconnections, not connections? Sure, assuming all connections are for equal durations, then the disconnection rate would be roughly equal to the connection rate, and, of course over the long term they will eventually trend towards equality, but that doesn't mean that the peak of connections in TIME_WAIT will not be greater than the incoming connection rate would suggest. Owen
Current thread:
- TCP time_wait and port exhaustion for servers Ray Soucy (Dec 05)
- Re: TCP time_wait and port exhaustion for servers JÁKÓ András (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Ray Soucy (Dec 05)
- Re: TCP time_wait and port exhaustion for servers joel jaeggli (Dec 05)
- Re: TCP time_wait and port exhaustion for servers William Herrin (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Owen DeLong (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Ray Soucy (Dec 05)
- Re: TCP time_wait and port exhaustion for servers William Herrin (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Mark Andrews (Dec 05)
- Re: TCP time_wait and port exhaustion for servers William Herrin (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Mark Andrews (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Ray Soucy (Dec 06)
- Re: TCP time_wait and port exhaustion for servers Miquel van Smoorenburg (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Mark Andrews (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Mark Andrews (Dec 05)
- Re: TCP time_wait and port exhaustion for servers William Herrin (Dec 05)
- Re: TCP time_wait and port exhaustion for servers Ray Soucy (Dec 05)
- Re: TCP time_wait and port exhaustion for servers JÁKÓ András (Dec 05)