lkml.org 
[lkml]   [2001]   [Oct]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: TCP acking too fast
kuznet@ms2.inr.ac.ru wrote:
>
> Hello!
>
> > Not very hard at all. It could be done easily with a couple of extra
> > state variables.
>
> Does current heuristics not work? :-)

Well, you should read the preceding messages to understand how we got
here.

Andi had some reservations and I tend to agree. The current heuristic
assumes specific TCP behaviour, which is left as an implementation issue
in specifications. Conclusion: it works if you're lucky.

But it's true I can't show you any data to the contrary, either. This is
not the issue that started this thread.

> > state variables. The following is a rough pseudo code (ignores
> > initialization of state variables):
>
> You missed one crucial moment: stream may consist of remnants
> for long time or even forever. It is normal case. And rcv_mss is used
> not only and mostly not for ACKing, it is used in really important places
> (SWS avoidance et al), where specs propose to use your advertised MSS,
> which does not work at all when you talk over high MTU interfaces.

I don't think I missed that point.

> The approach (invented by Andi?) provided necessary robustness,
> checking for two segments in row and suppressing MSS drops below 536.
> Check for PSHless segments allows to detect really low mtu reliably.

When you say "reliably", you should recognize the underlying assumptions
as well.

> Alexey

Regards,

MikaL
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:08    [W:0.045 / U:0.520 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site