Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucbvax!A.ISI.EDU!CERF
From: CERF@A.ISI.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: Re: TCP Fletcher Checksum Option
Message-ID: <[A.ISI.EDU].9-Dec-89.11:15:42.CERF>
Date: 9 Dec 89 16:15:00 GMT
References: <8911302213.AA00404@volition.pa.dec.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 18

Dave,

times are changing. The kinds of corruption we once  fought: line noise,
are being replaced by packet loss due to congestion or slips and
peculiarities which David Tennenhouse (LCS/MIT) warns may be visited
upon us by improperly implemented or functioning ATM switches: packet
internal reordering at the cell level.

It is by no means clear that reordering at the cell level will be
detected by the ATMs or by links level algorithms sending the
packets assembled from cells to the hosts since the link level
checksums would be recomputed AFTER reassembly, most likely.

At any rate, considering the question of integrity checking
in the current and anticipated internet environment seems
timely.

Vint