IPv6 allocations, deaggregation, etc.

George Bonser gbonser at seven.com
Tue Dec 22 19:44:56 CST 2009

We have decided to initiate the process of becoming IPv6 capable.  We
have requested and received a block of addresses which, after reading
some of the discussion here, I fear may be too small to suit our needs
(a /48).  To better understand how to proceed and in an attempt to get
it right (or close to right) the first time, I am soliciting opinions
and comments from other network operators.

It appears from earlier discussions on this list that while many
networks will not filter a /48 announcement in their routing tables,
others will.  We have data centers and offices in three regions of the
globe; North America, Europe, and Asia/Pacific.  We are also multihomed
as well as having some direct peering.  I can break my /48 into /56 nets
for each facility.  My thought process here being that if I have the
same transit providers at all sites, I can announce the /48 from my
primary location and that would get announced by the transit provider.
They would also accept my more specific routes but not announce them
outside of their AS.  So traffic originating outside of my transit
provider would flow toward them following the /48 and they then move the
traffic to the final destination based on the more specific and in the
case the traffic has no more specific route, hand the traffic to my main
location for me to sort out or just black hole it.  There are two
problems with this approach.  1: We are unreachable from anyone
filtering a /48 and 2: I could see a situation where traffic crosses the
Pacific, is handed to my transit provider, and then crosses the Pacific
again to get to the destination resulting in poor performance.

So it now seems to me that maybe a larger block might be the best answer
but being an "end user" the policies seem pretty restrictive on getting
a /32 though I might qualify for several /48 blocks (at least one in
each registry region).  So how does one reconcile having a diverse,
multihomed organization on several continents while at the same time
trying to do the right thing, not requesting more resources than we
need, and trying to be friendly to the various networks' operations by
advertizing only what we need to?  Is it unreasonable to get separate
/48 blocks for operations in Europe, North America, and Asia or possibly
two for Asia (one in China and one for Asia outside of China)?  While
that still won't help us with connectivity from networks filtering
/48's, it might relieve much of the back and forth transit across oceans
to get traffic originating from and destined for the same continent to
stay there.  I don't have a problem with regional backhaul tying an
office /56 to a data center announcing a /48 and using that data center
as a communications hub for the region.  It also assumes a transit
provider I am paying to haul my traffic will take "more specifics" for
internal use even if they aren't advertizing them.

I am just trying to minimize the stupidity and barriers to scale on my
side of the equation.

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