Subject: Re: (!) Vint Cerf designing network for solar system (!)

From: Vince Fuller <[email-masked]>
Date: Fri, 12 Mar 99 15:30:52 PST

[I'm probably going to regret this but at least there's some hope that use
 of a different email address will avoid my being added to yet another set
 of spammer lists...]

> It's quite simple.  And it all stems from the fact that we can never use
> address space in a dense fashion.  Remember that routing and addressing are
> inevitably tied.  If there is no structure to the address, then we have a
> flat network, which is clearly not scalable.  On the downside, as you
> structure the address, you lose efficiency.
> 
> You can see this today with an IPv4 prefix.  Utilization of a particular
> prefix can and historically has been quite poor.  You can find many numbers
> in the 10% to .1% range, depending on where you look.
> 
> Now, as you grow the network, the amount of state that you can support at
> any level is relatively constrained and must not outstrip Moore's Law.  It
> may be even more constrained if you want an economically viable solution.
> 
> So...  you need to have multiple levels of hierarchy, or what we know today
> as multiple levels of aggregation.  Each of these levels of aggregation is
> also, in turn, inefficient.  Note that this inefficiency is multiplicative
> with each level of aggregation that you perform.
> 
> Given these constraints, it's clear if the network is to scale, there needs
> to be many levels of aggregation, and that we're quickly looking at
> addressing efficiencies that are on the order of 10^-5 to 10^-12.  Sad but
> true.  

I'm surprised Noel hasn't already flagged this one - maybe he didn't want to
re-open this can of worms (though it is at least a technical can of worms,
unlike most of the recent flamage on this list...)

There is an unstated assumption in the above that "addresses" and any structure
that they have are relatively static objects. The "address" (at least in the
current IP architecture) serves two different purposes: one as an "endpoint
identifier" for host-to-host or application-to-application session definition
and one as a "locator" for describing where something is in the network
topology. By being forced to provide two very different functions, it does
neither particularly well. One could imagine separating these functions and
allowing more dynamic reconfiguration of the "locators" so that they map
exactly to the network topology. One might also imagine that such "locators"
could be relatively compact objects.
> 
> I think that it's clear that the next version of IP needs to be regarded as
> permanent infrastructure.  That means that it will be installed once, and
> persist indefinitely.  Like 120V 60Hz AC.  Like POTS.  
> 
> The problem with ubiquity is that it gives you a huge installed base
> problem.  And if there's no mechanism for incremental upgrades, you have no
> real hope of replacement.

Full agreement. This is why many people don't believe that IPv6 is the
right answer: it doesn't offer enough flexibility or enough of an improvement
over IPv4 to be a real, long-term solution. But you already know that...

	--Vince

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From: Keith Moore <[email-masked]>
Date: Fri, 12 Mar 1999 20:45:53 -0500

> There is an unstated assumption in the above that "addresses" and any 
> structure that they have are relatively static objects. The "address" 
> (at least in the current IP architecture) serves two different 
> purposes: one as an "endpoint identifier" for host-to-host or 
> application-to-application session definition and one as a "locator" 
> for describing where something is in the network topology. By being 
> forced to provide two very different functions, it does neither 
> particularly well. One could imagine separating these functions and
> allowing more dynamic reconfiguration of the "locators" so that they 
> map exactly to the network topology. One might also imagine that such 
> "locators" could be relatively compact objects.

only problem is, as soon as you separate addresses and locators, you
need a cheap, reliable, and reasonably secure (hard to spoof) way to 
map locators back to addresses.  afaik, nobody has demonstrated a good 
way to do this.  DNS is almost certainly not the answer - it's too 
unreliable, too slow, and too easy to get out of sync with reality.  

Keith

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From: Keith Moore <[email-masked]>
Date: Fri, 12 Mar 1999 20:45:53 -0500

Keith

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From: Bob Hinden <[email-masked]>
Date: Fri, 12 Mar 1999 19:20:06 -0800

>unreliable, too slow, and too easy to get out of sync with reality.  

A good analysis of the issues involved in separating identifiers and
locators in addresses can be found in:

	Title		: Separating Identifiers and Locators in Addresses:  
                       An Analysis of the GSE Proposal for IPv6
	Author(s)	: M. Crawford, A. Mankin, T. Narten, 
                      J. Stewart, L. Zhang
	Filename	: draft-ietf-ipngwg-esd-analysis-04.txt
	Pages		: 50
	Date		: 17-Feb-99

Bob

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From: Bob Hinden <[email-masked]>
Date: Fri, 12 Mar 1999 19:20:06 -0800

Bob