Of course, every ASN would not be active. But if we'd have 32 bit ASNs, there would be "no need" (or so folks would argue) to be strict in the policies -- everyone and their uncle could have one. Folks could even get ones for their homes, theis SOHO deployments, or their 3-person, on-the-side consulting companies. And logically, each of these should have their own PI prefixes and a slot in the global routing table.
People might argue it, but, I am not convinced they would succeed in that argument. If you want an ASN for something other than connecting to the internet for multihoming or other unique routing policy, then, make one up. Doesn't matter whether it's 16 or 32 bits. Also, there are a whole slew of private ASNs reserved for just such a purpose if you want to retain compatibility with existing ASN numbering. As such, I think that argument becomes specious in general. OTOH, I have a SOHO with a legitimate ASN and protable IPv4 space. Who are you to tell me that it isn't legitimate for me to use it in this manner? Why do you get to decide that my SOHO is less worthy of PI space and the ability to reliably multihome just because my organization is small?
Scalable? NO. Not just the number of routes, but also the churn those routes would make.. Oh god.
So we return to the need to separate the end-point identifier from the routing identifier and come up with a routing scheme that allows routing assignments to be dynamic and flexible independent of the layer 3/4 endpoint identifier.
It's better to try to stick to 16 bit ASNs for now, and make stricter policies and reclaim the space if needed.
No, it's not. It's better to expand to 32 bit ASNs now and realize that this is really just the most convenient way to get the necessary 20 bit ASNs that will happen whether we reclaim or not. Think about the difference between coding 20 bit ASNs and 32 bit ASNs and then ask yourself is there really any legitimate technical reason to code 20 bits instead of 32? Obviuosly, you don't subscribe to the premise that regardless of reclamation, we will run out of 16 bit ASNs soon enough. That's fine, you may be right. However, from where I'm sitting, I think we will. I also think that the $500 up front cost and $100 annual renewal associated with an ASN are decent incentive for people not to get them unless they have a legitimate use for them. Private ASNs are too easy and cost nothing. Owen