Re: [RRG] incrementally deployable

[David Williamson <dlw+rrg@tellme.com>]

On Wed, Nov 07, 2007 at 11:25:21AM +1100, Robin Whittle wrote:
> Incremental deployment means (perhaps amongst other things) that
> there are immediate overall benefits for the early adopters of a new
> technology.  Any scheme which requires complete upgrades of all BGP
> routers, all hosts etc. is not at all incrementally adoptable.
> Likewise, a scheme in which the address space managed by the new
> system is unreachable from non-upgraded networks is not
> incrementally deployable, because virtually all of the people who
> might initially adopt this new space would find the loss of
> connectivity a far greater problem than whatever benefits the new
> system provided.

I wanted to chime in on this point.  Incremental deployment is vital to
the success of any new routing methodology.  It doesn't matter how much
of an improvement any of the available proposals produce if it cannot
offer incremental deployment, as operators will simply not use it.

For non-incrementally deployable methods, there are only two choices
for a service provider like my organization.  We can either build
another instance of our entire service that uses the new method while
the old one continues to use traditional routing until our last
customer moves to the new scheme, or we can depend on a third-party for
some sort of proxy service between the two routing regimes.  The former
is clearly financially impractical, and the latter would require a
third-party capable of essentially zero downtime.  Neither option is
particularly palatable.

I haven't read deep enough into all of the proposals to figure out
which ones are incrementally deployable.  While I slowly work on that,
I hope that everyone involved keeps the practical requirements in
mind.

Thanks!

-David

-- 
David Williamson
Operations Architecture
Tellme, a Microsoft subsidiary 
<dlw@tellme.com> <dwilliam@microsoft.com>

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