North American Network Operators Group

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Re: The Gorgon's Knot. Was: Re: Verio Peering Question

  • From: Sean M. Doran
  • Date: Fri Sep 28 22:12:40 2001

Patrick writes:

|  >Wouldn't it have been easier for small ISP to just aggregate?
|  >I mean, /19s got through after all!
| No, it would not have helped.  Assume the prospective customer has a link 
| to UUNET and a /24, but wants a second link for [insert reason].  He now 
| goes to and asks for info on getting a second T1.  Then the 
| Sprint sales guy calls him and mentions that IF AND ONLY IF he buys a line 
| from Sprint, will Sprint hear his /24.

Let's see.  Firstly, this is a valid point, although I wonder how
Sprint's sales person could possibly know she or he should call
the customer in the first place.  Unless Sprint is known to employ
psychics, this seems like a bit of a stretch in producing a bete noire.

Secondly, /24 is not a small ISP, but wants a small ISP to back-up
connectivity to UUNET.  Valid goal.  However, asking small ISP
to ensure the world hears the hole in UUNET's CIDR block is not
a good solution.


	1. this is one reason why NAT was invented in the first place,
           and (hopefully) NAT is feasible for /24 (which is not an ISP)

	2. where NAT is impractical or even undesirable, Tony Bates and
	   Yakov Rekhter have a solution in RFC 2260 tailor-made to this

	3. the maximum 254 things in the /24 can be renumbered
           into small ISP's PA space and announced to UUWHO 
	   with a constraining (set of) community(ies)

	   (NAT, incidentally, was also invented to make renumbering easier)

	4. "creative value-added approaches to this problem are sold for $"

If the premise that /24 is not an ISP is false, then it should
renumber anyway into PA space which is readily available and
a generally understood cost of business for transit providers/ISPs.

Remember that the /19 boundary is both aligned with RIR policy,
which with its slow-start mechanism and fee structure is a really
low barrier for a prospective ISP while still putting some costs on
consumption of address space, and also small enough that it's
not a deadly pain to renumber anything containable by a longer prefix,
even without the assistance of NAT.

| NOTE: I am not saying this is good or bad, simply saying that what you 
| suggest would not be useful in this situation.

If I cover all the bases, exceptions, and gotchas I will write
fewer individual messages but my heaven will they ever be lonnnnnnng!

Market research indicates that this is not desired.


| "I realize that this is hard for you to wrap your brain around," but please 
| believe there may actually be other people on the planet who have the 
| brains to understand what they are doing and perhaps make a different 
| decision than you made for a good reason.

Requires evidence, and sometimes is undone by subsequent messages. I hope
you'll note my tone varies considerably in my various replies to people.