[e2e] New approach to diffserv...
Jonathan M. Smith
jms at central.cis.upenn.edu
Mon Jun 17 08:33:08 PDT 2002
> At 09:31 AM 6/17/2002 -0400, Jonathan M. Smith wrote:
> >This whole discussion has been highly amusing.
> >Let's just clarify some things that need to be clarified, perhaps with
> >some help from the high priests of e2e on the list :-)
> >1. Why is routing done with middleboxes?
> It isn't. A middlebox interprets data outside the IP layer. Often based
> on presumptions and heuristics that may or may not be valid.
But aren't routers middleboxes? The contain both routing functionality and
forwarding (the "IP" stuff). It seems to me, compared say to the
venerable source routing technology(!) that they are!
> >2. Where is the financial incentive to build networks if the basic
> >network architecture FORCES you to deliver a commodity with no value-added?
> There's lots of value added in delivering data more reliably, with lower
> latency, jitter, and ability to reach more destinations more quickly.
> Small rant: all businesses involve competition, except for those where the
> government grants monopolies (patents, rights-of-way, franchise
> laws). People invest in building them all the time, on the theory they can
> deliver the service more efficiently than others. The idea that no one
> would invest in a commodity business is so much horses**t, and is belied by
> the entire history business. It is the case, however, that this line
> about "no one would invest in a commodity business" is often used in
> regulated industries (telecom, historically) to con governments into
> granting exclusive monopolies, capturing their regulators. Whole
> generations of engineers then start to buy into this line.
> What is true is that no one will invest in someone who provides a service
> that is more expensive than its competition unless they have some way to
> rape their customers (er, add value) by what economists call "rent
> seeking". But networks have no special claim on "added value" - in fact,
> users would probably move off those networks that try to impose "added
> value" if there were no laws on every state and country's books granting
> exclusive licenses to rights of way, etc.
Well I didn't say that no one would invest in a commodity business - it's
clear that's not true. But here is the more relevant question - will innovation
occur as quickly without big enough profits to sustain risks? What do
you think? I think in commodity businesses the margins are thin - so it's
tough to sustain such luxuries as forward-looking R&D. Thoughts?
> >3. Why is the network engineered in isolation from applications?
> It's called modularity. The network is useful for a wide variety of
> applications, most of which are not known, or their future value is not
> known. Thus we do a general purpose network that allows a wide variety of
> uses. Especially important because large parts of the economic value of
> networks comes in the form of increasing returns to scale and
> interoperation, so dividing the network up and optimizing each piece for a
> different use destroys value.
> It's not fair to say it is engineered "in isolation", by the way. In
> fact, the last network that was engineered "in isolation" was X.25, which
> ignored applications entirely to create a perfect virtual circuit
> architecture layered on packets. The Internet had strong input about the
> general characteristics of computer-computer communication that differed
> from telephony's isochronous circuits. But this was balanced by a strong
> desire to bind *any* particular application's requirements into the network
> - if we had observed the dominant use of the ARPANET (remote login to
> timesharing systems) and optimized around that, the Internet would have
> failed completely.
Sure. I was being extreme to provoke discussion. But I think of distributed
applications with multicast semantics and how hard it has been to get
multicast into place in the network, in spite of (what appear to be)
good designs? How can you explain that?
> >4. Isn't e2e just a clever logical deception? It's of course obvious that
> >an engineered artifact will have the maximum longevity it if it avoids
> >any concession to current needs, but very few of us buy wheels, chassis
> >and motor, instead opting for value-added services such as seats and a
> >roof. E2e is just rhetorical "argumentum ad absurdum" wrapped up like
> >some engineering mystique, no?
> Read "Design Rules" by Baldwin and Clark. It explains the economic linkage
> between modularity and economic success.
> Following their approach one can see a lot of the value of the e2e argument
> (and Mark Gaynor did just this in his recent Ph.D. thesis). The end-to-end
> approach is an approach to maximizing the value of an architecture in the
> face of large market uncertainty. It does not apply when the market
> requirements for all time are precisely known. But in the case of
> internetworking, that does not seem to be anytime soon. Perhaps when the
> world information economy is mature and unchanging in scale or structure -
> but is that 50 years or 1000 years hence?
/* irritating statement warning */
But of course doing nothing is safe!
/* end irritating statement */
Granted. But you seem to ignore that risk is a continuum, no?
I will follow up your reading suggestions - they sounds fun.
Is Gaynor's thesis on-line? I'll have a look before I continue in this
More information about the end2end-interest