[ NNSquad ] Success of the Internet

["David P. Reed" <dpreed@reed.com>]

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.