> > Why has this mail taken 5 days to reach? And isn't this the second time
> > it's coming through?
>
> It came through only once for me, and on time:
Actually, it was not the only mail that came through twice for me. There
were three of them (all deleted now so I can't check.)
Can anyone explain this? I figure, once a mail gets into the send queue,
it waits there until a route is available. At that point, it is sent
to the destination through all routers.
For a mail to reach 5 days late, it would have to be stuck up either for a
really long time in the queue, or be bouncing around routers for a long
time.
If it was stuck in the queue, it would not have been received the first
time, there fore that option is ruled out.
If it were bouncing around a lot of routers, it would definitely time out
before 5 days.
I can think of one more possibility albeit highly improbable. (Frankly, I
don't think it's true, but is interesting nonetheless).
The mail is sent to the recipients on the list.
The particular copy that has to get to me takes a different route. On
it's way, some router does not receive one packet, so sends a NACK to the
previous router. This NACK takes long to reach because of network
traffic. Now, the route between these two routers is so clogged, that the
previous router decides to send the mail along a different route. It
resends all the packets, because the ACK's for them haven't gotten back
yet.
Meanwhile, the original route has cleared up, and the last packet reaches
the original router. Thus, we have two copies of the same mail, both
addressed to me, taking two different routes. The first arrives
immediatedly (allowing for propagation delay), while, the other (original)
was stuck in router buffers for 5 days waiting to get out.
It was a low priority packet (as are all mails regardless of the priority
flag.) so kept getting pushed back into the queue everytime a higher
priority packet (like SETI data) came through.
Highly unlikely, but what do you think of my theory?
Philip
:)
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