Large global enterprises, multi-homing, and inconsistent announcements

[Craig A. Huegen]

On Wed, 18 Apr 2001, Richard Jimmerson wrote:

> It is ARIN's understanding that the community prefers ARIN not become
> involved in establishing global routing guidelines.  Does this continue to
> be true with IPv6?

The reason I bring this up is because regardless of whether it's desirable
or not, service providers today are basing their v4 routing filters upon
allocation size.  Address space in 64/8 is much more flexible from the
perspective of an end user's ability to divide the block into regional
chunks, compared with 128/2 space.  Cisco ran into this in the past year
where, in an attempt to efficiently use the space granted to us over the
years, we wanted to announce portions of 163.213.0.0/16 as 4 sub-blocks,
each from one of our access points within the Asia-Pacific theatre.  This
would have resulted in a handful of providers not accepting the
announcements.

We had two choices:

* we could contact those providers we knew that filtered, and ask them to
  make exceptions for us.  Some of them refused, citing their legal
  departments would not let them make the necessary exceptions.  The other
  issue with this approach is that it's impossible to find out, except
  through a reactive approach, which providers are filtering and then make
  the necessary contacts to allow the blocks through; or,
* we could renumber into another block.  We did this, taking on
  significant expense to renumber into a like-size block that wasn't as
  tightly filtered.

I believe that through the adoption of the IAB/IESG recommendations, ARIN
is affirming some of the concepts that pertain to routing.  Whether or not
it's believed that ARIN should be involved in establishing them, it's
happening as the guidelines exist today.

Perhaps this could wait until the whole debacle surrounding multihoming
settles; I recognize that it may drive some of the decisions made
regarding these large enterprise networks.  Until some of those decisions
are made, any planning that's done by these enterprises (and therefore,
later: adoption) is going to be a dartboard throw.  It's harder to justify
within many of these enterprises.

/cah

---
Craig A. Huegen  CCIE #2100                       C i s c o  S y s t e m s
Sr Network Architect, GCTS                              ||        ||
Cisco Systems, Inc., 400 East Tasman Drive              ||        ||
San Jose, CA  95134, (408) 526-8104                    ||||      ||||
email: chuegen at cisco.com                           ..:||||||:..:||||||:..