A non-routing problem.


1017263%MCMASTER.BITNET@WISCVM.WISC.EDU
26 MAY 86 13:44-EDT


Here is a problem from the world of TCP/IP. Why does the Vax retransmit a
packet which has been acknowledged ? Also if the PC does window shrinking and
the window size becomes zero at the point of transmitting the character, the
retry time can be about 30 seconds.

The following is a true log of packets between the Vax and the PC. Only the
names have been changed to protect my innocence.

              From PC From Unix/Vax
           (Using BWTEL)

                                                Characters = 82
                                                Seq # = 207
                                                Ack # = 32
Characters = 0
Seq # = 32
Ack # = 289
                                                Characters = 82
                                                Seq # = 289
                                                Ack # = 32

*** Character transmitted before last packet processed

Characters = 1
Seq # = 32
Ack # = 289

                                                Characters = 0
                                                Seq # = 371
                                                Ack # = 33

This packet is in response to second to last packet, last packet not yet
processed.

Characters = 1 same character as above
Seq # = 32
Ack # = 371
                                                Characters = 0
                                                Seq # = 371
                                                Ack # = 33

                                                Characters = 82
        *** Seq # = 289
                                                Ack # = 33

*** Why Does the Vax retransmit ???? ***

Characters = 0
Seq # = 33
Ack # = 371

                                                Characters = 82
                                                Seq # = 371
                                                Ack # = 33
Characters = 0
Seq # = 33
Ack # = 453

                - Carl Beame 1017263@MCMASTER.BITNET or
                             BEAME@MCMASTER.BITNET

P.S> Any comments or explanations are very welcome.



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