Subject: Re: Status of the 16-bit AS Number space

From: Florian Weimer <[email-masked]>
Date: Tue, 05 May 2009 20:22:27 +0200

* Steve Crocker:

> I strongly advise against quick reallocation of returned AS numbers.
> Returned AS numbers should stay out of service for a substantial
> period of time.

Why?

It seems to be consensus among operators that it's fine to use other
people's ASNs in the global routing table, so such reuse shouldn't
pose any additional problems.

---

From: john heasley <[email-masked]>
Date: Tue, 5 May 2009 12:53:59 -0700

> pose any additional problems.

It IS fine to use an ASN that has been assigned or loaned to you.

The question is why there should be moratorium on returned ASNs.  I can
think of one reason that could be of dis-service to a new assignee, but
all we have so far is handwaving from the proponents.

---

From: Bill Manning <[email-masked]>
Date: Tue, 5 May 2009 21:02:50 -0700

> _______________________________________________

 a thought experiment.

	John is properly assigned AS 701
	John uses AS 701 for a number of years, then his project is 
		canceled and he decides to return it.
	John properly returns AS 701 to his RIR via the automated processes.
	The RIR notes the availability of this AS and in 15ms, reassigns it
		to, say VZB.
	VZB automated systems notice and promptly announce VZB prefixes from
		AS 701.

	Is the 15ms moritorium excessive?  

--bill
Opinions expressed may not even be mine by the time you read them, and
certainly don't reflect those of any other entity (legal or otherwise).

---

From: Mans Nilsson <[email-masked]>
Date: Wed, 6 May 2009 08:49:42 +0200

>  a thought experiment.

<snip>

> 	Is the 15ms moritorium excessive?  
 
No. Perhaps even short. A month should be appropriate. Those who update
their filters based on RIR data with some support system assistance do
so daily/weekly. Those who have manually updated filters are losing
this battle already, and those who accept any from any are utterly lost
(but in this particular instance in ignorant bliss). 

Only clue helps these cases; no moratorium will ever save them.

--

---

From: Florian Weimer <[email-masked]>
Date: Wed, 06 May 2009 21:26:52 +0200

> 	VZB automated systems notice and promptly announce VZB prefixes from

The consensus seems to be that VZB can use AS 701 while John is using
it (mainly for routing engineering purposes).

The situation is markedly different for addresses (where consensus
does not seem to exist at all).

---

From: john heasley <[email-masked]>
Date: Wed, 6 May 2009 14:37:55 -0700

> (but in this particular instance in ignorant bliss). 

That is the "disservice" that I had in mind.

ASNs I returned nearly 10 years ago have not been reassigned.  Surely
sufficient is far fewer than 10 years.  16 bit exhaustion is magnified by
policy.

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