Messages in this thread |  | | Date | Sun, 14 Oct 2001 20:26:01 +0300 | From | Mika Liljeberg <> | Subject | Re: 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/
|  |