Routing wars pending?
jnc at ginger.lcs.mit.edu
Wed Nov 15 19:40:03 UTC 1995
<CIDRD is the wrong list for this: CIDRD is for *deployment*, not
architectural debate. Please follow-up on Big-Internet.>
From: Tim Bass
Then, in parallel, CIDR was hailed as the 'way to help save B space
[depletion] problems'. ... very surprised to learn that our vision of
"completely portable" CIDR address space have been overshadowed by the
success of CIDR in another problem area that only those with keen insight
at the time could predict, routing table explosion.
You keep saying this, but it is *NOT TRUE*. You didn't need "keen insight" to
know it was coming, you only needed to be able to *read*, viz (from
"Supernetting: an Address Assignment and Aggregation Strategy" RFC-1338, June
As the Internet has evolved and grown over in recent years, it has
become painfully evident that it is soon to face several serious
scaling problems. These include:
2. Growth of routing tables in Internet routers beyond the
ability of current software (and people) to effectively
It has become clear that the first two of these problems are likely
to become critical within the next one to three years. This memo
attempts to deal with these problems by proposing a mechanism ...
So, the routing table problem was well known to be coming at the time that
CIDR was under discussion, and the effects of CIDR on address allocation were
pointed out in *great* detail in a discussion on the *main* IETF list (look in
the archives for the thread "Re: Vote NO on R-L-G IP Address Allocation
proposal", and in particular my message of "Sat Oct 31 19:26:04 1992", the
infamous "fnortz" message, which pointed out in some detail why renumbering
was inevitable). So, if anyone who are around then missed it, they have only
themselves to blame.
I am damned tired of people rewriting history. Please cease and desist before
I become extremely upset.
after all, CIRD was only to be an *interim solution* for a few years for B
space depletion. IPv6 would take care of that. ... aggregation was
now the accepted practice for solving most I problems and was not an
*interium* or temporary fix, but was to be a core Internet solution.
There is a certain amount of truth to this. CIDR did assume that some "better"
fix was coming as part of IPng (and let's not forget, the CIDR debate predated
the IPv6 debate - SIP only started to be discussed late that summer).
However, as is now I hope obvious to everyone, it's impossible to have a
single namespace which is both i) used directly for routing, and ii)
identifies hosts directly. To get rid of "renumbering", the Internet needed to
split "addresses" as host-identifiers from "addresses" as routing-names,
and map one into another.
No matter how hard I and some others argued for doing this, though, people
didn't want to take that "radical" step of two namespaces. Everyone's moaning
now about the painful consequences? Tough.
(I take great delight in the fact that one of the principal opponents of
splitting off the host-identification function is also one of the people most
upset at renumbering. I expect by now, with hindsight to help his understanding
along, the irony will have dawned on him.)
Technically, the aggregation advocates were correct. Socially and
politically, aggregation on a global cooperative scale has problems.
Which is why we need *two* namespaces: one for the routing to do what
mathematics forces it to, and one for the humans to be able to dork with.
there are future social and political implementations of global aggregation
that are negative.
There are some very painful routing consequences, even with two separate
name-spaces (e.g. things like inbound traffic bias), but these are technical
problems which will only admit of technical fixes. We have to investigate
various possible technical solutions, and weigh the costs of them against the
benefit of doing it the way we'd like, but that debate has to be a purely
technical one, *not* a policy debate.
Now, let's see, where are my winterized, flame proof, long johns? After
this email, I'm sure to need numerous layers :-) ;-)
Hah! When I get *really* grumpy, you better have something better than
miserable protective clothing! Try a bunker reinforced to +125 PSI blast
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