RE: The state of IPv6 multihoming development

["Tony Li" <Tony.Li@procket.com>]

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Back when we were doing the CIDR work, we asked a bunch of
ISPs and they came back with about 10% of their customer
base being multihomed.  And typically, the second 
provider wasn't part of the sample, so that we felt that
about 10% of all enterprises were multihomed.

During the bubble, it looked like that number was increasing,
but post-bubble, I'd make the educated guess that it's 
back to 10%.  This may well increase as more enterprises
find that the net is mission critical to them.

A side point: another result that we got from CIDR is that
even at 10% of the enterprises being multihomed, that their
contribution to the DFZ tables would come to dominate the
size of the table and push us back into exponential growth
extremely quickly.  Or, another way of looking at it is
that when you have exponential growth, dividing the problem 
by 10 only gets you about one growth cycle of relief.  It
doesn't solve the issue entirely.

Will homes, academia and non-enterprises multihome?  Some
academic sites already are.  I know of some sick netgeeks
who are already multihomed.  All of it hangs in the balance
between the economic cost and the perception of mission 
critical importance.

Bottom line: we need a multihoming solution that allows
the DFZ table to scale reasonably even if everyone is multihomed.
Because that might happen and the net must continue to work.

Tony

p.s. In the past I have certainly been an opponent to IPv6.
However, my position has changed somewhat.  I can see the
pressure to go down the IPv6 path and I would like to see
some good come out of the exercise.  If v6 turns out to be
simply v4 with a bigger address space but it still collapses
due to the poor routing architecture, then we will have
failed miserably.  So I am pushing for scalability for the
routing layer and hoping that we don't make the same mistakes
again.  -- t


|   -----Original Message-----
|   From: Tim Chown [mailto:tjc@ecs.soton.ac.uk]
|   Sent: Tuesday, October 22, 2002 4:27 PM
|   To: Tony Li
|   Cc: Multi6 Working Group
|   Subject: Re: The state of IPv6 multihoming development
|   
|   
|   On Tue, Oct 22, 2002 at 04:08:56PM -0700, Tony Li wrote:
|   > 
|   > It's vitally important in the sense that if we deploy
|   > the wrong solution (or no solution), then we end up back
|   > on the exponential curve and it will be that much harder
|   > to change later because we would then have an installed
|   > base.
|   > 
|   > In other words, the sequence should not be: ready, fire, 
|   > aim.
|   > 
|   > ;-)
|   
|   OK, containment (of the DFZ table size) is certainly a good goal.
|   
|   But who is actually going to be multihoming with IPv6, and 
|   to what extent?
|   Perhaps there are now 50,000 large enterprises doing so 
|   with IPv4.  Is the
|   number of such enterprises going to rise?   What's the 
|   change in terms of
|   the types of sites multihoming that's pushing the DFZ size 
|   up so much?
|   Small ISPs?  Smaller enterprises?
|   
|   I'm just curious as to who the multihomers are, and best 
|   guesstimates of
|   future growth.   Do we foresee home users multihoming to 
|   multiple ISPs?
|   I don't pay for resilience now with two telephone lines, or 
|   having DSL and
|   cable lines; paying double isn't economic for Joe User.   
|   The same I assume 
|   would be true for mobile handsets.   Academia + home users 
|   + mobile (3G) users
|   is (or will be) a large chunk of the Internet;  all three 
|   can benefit from 
|   IPv6 now, or in the near future.
|   
|   The crux seems to be projected top limits on who will 
|   demand multihoming,
|   and what clas of users those people/sites are?   Of course, 
|   predicting 10
|   years ahead is a tad tricky :)
|   
|   Any pointers to research/stats on this would be interesting.
|   
|   Tim
|