RE: Status summary on multiple connections

["Lyndon Ong" <long@nortelnetworks.com>]

At 08:05 AM 10/2/2000 -0700, Y P Cheng wrote:
>Randall and Mark:
>
>Both of you forget about the case when multiple PDUs are inflight, say N,
>N+1, and N+2, and one of them has CRC error, say N+1.  The receiver throws
>away N+1 because the bad CRC.  N+2 is received long before N+1 is
>retransmitted after a timeout by the sender.  Of course, a sequence number
>inside the PDU will ensure sequentially.  However, as I stated in another
>posting, all software realize such problem and will not count on sequential
>delivery by a transport.
>
>Y.P.

This confuses me.  Why would the application ever see the N+2 PDU, wouldn't 
it be queued by TCP until N+1 is delivered correctly?  It shouldn't matter 
if N+2 was delivered first or if it contains a sequence number at the 
higher layer, the higher layer would not get N+2 before N+1.

TCP would presumably not be aware of the boundaries between messages at the 
higher layer, but deliver what it sees as a stream of bits.

Cheers,

L. Ong