Success of the Internet

[David Farber <dave () farber net>]

Begin forwarded message:

From: "David P. Reed" <dpreed () reed com>
Date: September 29, 2009 9:31:38 AM EDT
To: nnsquad () nnsquad org
Subject: [ NNSquad ] Success of the Internet

On 09/28/2009 10:25 PM, Richard Bennett wrote:
> The real rationale for the datagram network architecture was to  
> create a space for experimentation; that's why everybody embraced it  
> as soon as it was formulated. This internetting thing was actually a  
> flop; we actually have one big network made of self-similar parts,  
> not a bunch of different ones. Interconnection works best if  
> everybody runs all the same protocols, so we do.
Richard, this is what they call a "just so story".  A myth made up to  
explain origins.  Like Kipling's "How the Elephant got his trunk".

1) Asserting that "the real rationale" was to create a space for  
experimentation is historically wrong, as is the claim that "everybody  
embraced it as soon as it was formulated".  This is neither true of  
the project to design and build the Internet protocols, nor is it true  
about earlier datagram arguments.  I say this as one of the people who  
argued strongly for splitting TCP into two layers - TCP and IP, and  
creating the space for the User Datagram Protocol.  This decision,  
made by the group of TCP designers, and was hard fought for many  
reasons.  It was a good decision, but it was hardly "embraced by  
everybody" - in fact much of the Internet community continued to claim  
it was a mistake - that datagrams were a bad idea for congestion  
control and other things, in other words for "network management".

The same thing is true for Pouzin's arguments, of which we were *all*  
aware - at least those of us who fought to put first-class datagrams  
into the Internet.   Pouzin's ideas were resisted, in both the  
traditional "bell" community's approach to packet networking, and the  
research community, except by a few folks who saw that networks  
between computers that were only imagined would be much better suited  
by message-exchanges and complex multiparty protocols.

So much for that part of the "just so story" - "How the Internet got  
its architecture"

2) The idea that we actually have "one big network made of self- 
similar parts" is meaningless as a description of the Internet as it  
is.  Perhaps that is the "ideal" that is described as a desirable  
state of affairs in John Day's book.  But it's not real. First of all,  
the network functions are not present in the same form or the same way  
at all levels.  Day considers only routing and flow control to be  
"network functions", and even there he is wrong: the routing and flow  
control mechanisms of the 802.11 MAC (which I can't resist pointing  
out that *you claim to have been responsible for*, though most doubt  
your claim has much to it) are not "similar" in any respect to the  
routing and flow control within the DOCSIS access network or the  
original ARPANET that carried some of the Internet's traffic in its  
latter days.

In fact, the Internet is full of diversity, both below the neck of the  
hourglass (IP) and above it.  And the neck of the hourglass, while  
providing some unity among many diverse parts, hardly makes it a "one  
big network" - it retains a great deal of flexibility because the IP  
layer divides very clearly what endpoints can expect and what networks  
can do in a way that is universally adoptable.  But that layer implies  
a minimal set of agreements - each one crucial to creating the  
internetworking story.

3) Finally, your language in saying the "internetting thing was  
actually a flop" is absurd.  The entire history of the Internet was  
growth by including more and more networks into the overall thing.    
The design was specified to be able to run over any kind of network -  
for the reason of being able to integrate networks of many diverse  
types.  Unlike John Day and others who might think that we could throw  
all those old technologies (DSL designed for video dialtone, ISDN for  
smart phone instruments, Ethernet for local areas only, Bitnet, Frame  
Relay for backoffice interconnect, ...) away and build a new network  
from scratch, the Internet succeeded, and continues to succeed, by  
absorbing new technologies and networks, according to the relatively  
successful formula of transporting IP packets on top of any old kind  
of network that can be made to be:
   1) addressable by some kind of binding (ARP, ...),
   2) capable of forwarding IP datagrams between gateway routers,
   3) not needing to inspect the content of IP datagrams to do the job,
and
   4) capable of signalling congestion or failure by dropping (and  
optionally marking) IP datagrams.

It took a long time to sort out all the issues of the Internet's  
deployment, because of the diversity of infrastructure, not because of  
illusory "self-similarity"

This is actually not a "flop", but the opposite.  No other  
architecture for networking has been so successful.






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