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Re: BGP Question - how do work around pigheaded ISPs

  • From: Craig A. Huegen
  • Date: Sat Feb 10 00:36:13 2001

On Fri, Feb 09, 2001 at 07:35:31PM -0800, Roisman, Dani wrote:

==>- The Premis:
==>A parent organization has an unused /16 of address space, for arguments
==>sake, let's say it's 172.16.0.0/16.  It's out of the old "class B" address
==>range.  Two groups within the organization want to bring up independant
==>Internet datacenters, and need /18 of address space, each.  Since the parent
==>organization owns an unsed /16, the IP registry refuses to give the child
==>organizations any address space - they insist all address blocks assigned to
==>the parent organization be used, first.

This is a frequent problem for those who have had address space from some
of the older blocks and are trying to go back and better handle.

You don't have to allude to who these ISP's are, they publically state
their policies.  Typically, for these ISP's, one premise is that
filtering based on the minimum prefix size that the registry allocated
in that particular /8 shields them from legal challenges related to
having any sort of filtering policies in the first place.  IMO, it just
makes the liability greater.

After all, what's the difference between 171.16.0.0/19, 171.16.32.0/19 and
64.255.0.0/19, 64.255.32.0/19, as long as the companies who are announcing
the blocks are doing so responsibly and for good reason?  Why should the
first set be filtered but the second not?

The next answer that you'll receive are "some of the older companies don't
know how to responsibly announce their address space", because some do
announce them as /24's.  I think that a responsible policy which limits the
announcements in the old B space to the minimum allocation ARIN is
currently utilizing, or even /19, is perfectly sufficient.  It keeps
routing tables under control and protects against the infamous UUnet
de-aggregation disaster or bad announcements with lengths longer than,
say, /20.

Yet another off-the-wall answer you'll get is that some ISP's have
taken it into their own hands to stop announcements longer than /16's
because some old companies might want to sell portions of their /16's to
make money.  With all the dot-coms closing, I think I'd be more worried
about 209+ and 62/63/64... =)

And finally, there's always the "there might be a chance someone will
pay us to amend our filters for their slot" argument.

/cah





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