[Standards-JIG] Re: The Ack Hack.
m at tthias.eu
Sat May 13 21:44:37 UTC 2006
Michal vorner Vaner schrieb:
> No, it just forces TCP to be sending something and discover it is dead.
> Connection that does not send anything will look like alive even if long
> time dead.
That's not always true. TCP knows (optional) ways to discover broken
connections even if nothing is transfered.
>> Some people told me that there are difficulties working with tcp under
>> different OSes. That you sometimes can't get the info about what was sent and
>> what was not sent.
> No, this is the same on all OSes. You put data to the socket and expect
> it to get there. And TCP is designed to either deliver it or die. So, if
> it ends OK, you are sure everything got there. If it dies in unclean
> way, you shuold consider the whole stream as invalid. TCP was not
> designed to keep long-term connection, but to transfer data and
The problem with have "with TCP" is not really a problem with TCP but
with the design of a "socket" which is our typical interface to a TCP
connection. TCP knows exactly what has been transfered (and ACKed) and
what hasn't. It's just the socket interface, that does not give this
information to the upper layers.
Therefore you can say that this is a problem with the OSes (which
implement the socket) and not with the TCP protocol.
Matthias Wimmer Fon +49-700 77 00 77 70
Züricher Str. 243 Fax +49-89 95 89 91 56
81476 München http://matthias.wimmer.name/
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