Re: question about TCP checksums
> Date: Tue, 20 Oct 1998 09:14:35 -0700Nothing, other than noting the fact in local statistics.
> From: "Eric A. Hall" <ehall@...>
> Subject: question about TCP checksums
> Various documents seem to be at odds with each other regarding the
> proper behavior for responding to a TCP segment that has an invalid
> checksum. Although STD 7 states that the segment should be discarded, it
> doesn't state what should happen next.
> Some material suggests that the recipient shouldn't do anything, waitingYes.
> for the sender to timeout and retransmit. Conversely, other materials
> suggest sending an ACK for the last successfully-received segment.The "other" scenario is wrong. Though you know that the IP source and
> Either method would seem to work, with the benefit depending on the
> exact scenario.
destination addresses are correct (since they are part of the IP header,
and IP would have tossed the packet if the IP checksum was bad), you
don't know that the TCP source/destination ports are correct, because
the TCP checksum is bad. Thus, you can't be 100% sure that you would
even know who to send the ACK to.
> The question is: what's the position of the group as to which method isSilently drop the packet, since when you have a TCP checksum error
> the enforcable STANDARD method?
you can't be 100% sure that you know for which connection the packet
was destined. TCP will retransmit the dropped data.
> Thanks-David Borman, dab@...
> Eric A. Hall ehall@...
> +1-650-685-0557 http://www.ehsco.com