Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!agate!ucbvax!NSIPO.NASA.GOV!medin
From: medin@NSIPO.NASA.GOV ("Milo S. Medin", NASA ARC NSI Project Office)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: fragmenting broadcasts
Message-ID: <8905062121.AA03774@cincsac.arc.nasa.gov>
Date: 6 May 89 21:21:30 GMT
References: <8905041715.AA00694@braden.isi.edu>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 33

>Date: Thu, 4 May 89 10:15:25 PDT
>From: braden@venera.isi.edu

...
>I gather your application will be used ONLY across a single Ethernet, with no
>gateway hops, in an environment which is sufficiently constrained that
>you assume reliable delivery from the link layer.  You're sure no site
>will ever try to run it through a gateway (leading to congestive losses).
>There is an enormous amount of experience that such ideal enironments
>don't last; customers want to use the fact that these are INTERNET
>protocols, and your assumptions collapse into a "puddle of glup."
>You then discover you have to provide some reliable delivery in the
>application, in which case the fragmentation/reassembly needs to be
>in the same layer, or performance becomes terrible.

...

>Bob Braden

It's not just only on an Ethernet without ever going through a gateway.
Many people these days bridge ethernets together with low cost bridges
that may drop packets under severe load.  Also, other bridge
ethernets with low speed (56 Kb) serial lines.  I am aware of
certain circumstances where some bridges will drop packets in
bridge queues in cases involving topology changes, and in cases
of congestion.  Also, losses on serial lines between bridges can
also introduce lossage...

So it's any sort of packet switch involved.  Gateways certainly
aren't the only source of packet attenuation!

					Thanks,
					   Milo