IPv4 address shortage? Really?

Steven Bellovin smb at cs.columbia.edu
Tue Mar 8 07:43:53 CST 2011

On Mar 8, 2011, at 8:32 59AM, Valdis.Kletnieks at vt.edu wrote:

> On Tue, 08 Mar 2011 07:37:27 EST, Steven Bellovin said:
>> No.  It  was rejected because routers tended to melt down into quivering
>> puddles of silicon from seeing many packets with IP options set -- a fast
>> trip to the slow path.  It also requires just as many changes to applications
>> and DNS content, and about as large an addressing plan change as v6.  There
>> were more reasons, but they escape me at the moment.
> Steve, you of all people should remember the other big reason why:
> pathalias tended to do Very Bad Things like violating the Principle of Least
> Surprise  if there were two distinct nodes both called 'turtlevax' or whatever.
> That, and if you think BGP convergence sucks, imagine trying to run pathalias
> for a net the size of the current Internet. :)
It wouldn't -- couldn't -- work that way.  Leaving out longer paths (for many,
many reasons) and sticking to 64-bit addresses, every host would have a 64-bit
address: a gateway and a local address.  For multihoming, there might be two or
more such pairs.  (Note that this isn't true loc/id split, since the low-order
32 bits aren't unique.)  There's no pathalias problem at all, since we don't
try to have a unique turtlevax section.

		--Steve Bellovin, http://www.cs.columbia.edu/~smb

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