Re: TCP connection tracking timeout

[Patrick McHardy <kaber@trash.net>]

Herbert Xu wrote:
> On Tue, Jul 29, 2008 at 07:00:46AM +0200, Patrick McHardy wrote:
>>> That sounds like a pretty neat idea. I'm testing a patch now, I'll
>>> send it over in a few minutes if it survives :)
>>>       
>
> Awesome! I'll try this out on my router.
>
>   
>> This seems to work. I'm wondering however if this will really help.
>> We already track retransmissions and decrease the timeout on the
>> 3rd retransmission, so this should only help if both the sender and
>> the receiver went down.
>>     
>
> The problem with requiring a 3rd retransmit is that once a socket
> is orphaned (closed) on Linux, we fast-track the retransmit timeout
> process.  In particular, if it's already maxed out the RTO prior
> to closing, we'll kill it straight away.
>
> This is in violation of the RFCs but it's an important optimisation.

Thanks for this explanation. Unless Jozsef sees something wrong with this
patch, I'll queue it with a proper changelog. Its small enough, so perhaps
we can even put this in 2.6.27.