TCP time_wait and port exhaustion for servers

Ray Soucy rps at maine.edu
Wed Dec 5 20:00:44 UTC 2012


There is an extra 7 on that number, it was 48194 (was sitting on a
different PC so I typed it instead of copy-paste).

On Wed, Dec 5, 2012 at 1:58 PM, William Herrin <bill at herrin.us> wrote:
> On Wed, Dec 5, 2012 at 12:09 PM, Ray Soucy <rps at 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_WAIT
>
> Stupid 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?
>
> Regards,
> Bill Herrin
>
>
>
>
> --
> William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
> 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
> Falls Church, VA 22042-3004



-- 
Ray Patrick Soucy
Network Engineer
University of Maine System

T: 207-561-3526
F: 207-561-3531

MaineREN, Maine's Research and Education Network
www.maineren.net



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