bradg@zaphod.UUCP (Brad Gorzitza) (02/07/91)
I have two tcp questions for this news group. My apo-
logies if the answers appear in the RFC's somewhere or if
these questions have been answered here before. Anyway,
here goes.
First question: consider the following setup.
--------------- ------- ------- ---------------
| Application | | TCP |==================| TCP | | Application |
| A |+++++| A | Lan | B |++++| B |
_______________ _______ Connection _______ _______________
Application A stops accepting data from TCP A. Appli-
cation B continues sending data via TCP B until TCP A runs
out of buffers and advertises window of 0. After a while,
Application B closes the connection. What should TCP B do?
According to RFC 793, SYN and FIN are included in the
window (to give them retransmission protection). Hence, TCP
B supposedly cannot send a FIN until TCP A opens its window
again. Is this the case? If I want TCP B to exit could I
simply have it do so, perhaps after sending a RST? Or am I
bound by the RFC's to let things run their course?
Second question: consider the following. TCP A is
sending data to TCP B. *No* data is being sent the other
way.
TCP A TCP B
----- -----
send X bytes of data ---> <received>
seq # = Y ack # = Z
<lost> <----- seq # = Z ack = X+Y
send X bytes of data ---> <Old data already
seq # = Y ack # = Z acked; silently
discarded>
. . .
. . .
. . .
. . .
<connection reset at this
end due to no response>
My question is should TCP B retransmit its ack upon
receiving a retransmission of data?
Anyway, thanks in advance to any and all who reply. As
this might be of interest to others, it might be an idea to
reply to this newsgroup.
--
____________________________________________________________________________
Brad Gorzitza bradg@zaphod.uucp
Develcon Electronics "If this is the road we take to our dreams,
Saskatoon, Sask. do we walk in vain?" T'Pau