Subj : V4 to V6
To   : Neil Croft
From : Lawrence Garvin
Date : Wed Jan 31 2001 10:55 pm

Neil Croft said in a message to All:

 NC> Hiya All,

 NC> Does anyone have any views on how the world (and the rest of us)
 NC> will move from IPv4 to IPv6 given I haven't yet seen an operating
 NC> system or a router (Cisco or 3Com) that will accept a 16 byte
 NC> address?

Actually, Neil, most of all of the new hardware supports IPv6 and the major OC 
backbone providers claim to already be using IPv6 -- however, I must admit, 
I've not made any effort to actually implement IPv6 addressing on any networks 
I work with.

However, my personal take is that with the advent of NAT, firewalls, etc. that 
the need for IPv6 has been significantly delayed over the panic that was 
achieved a few years ago. I see that most people have realized that we're not 
really running out of IPv4 addresses anymore.. well not as fast as we might 
have been 3 years ago.. and the hype to get the new system in place is less 
critical.

On the other hand.. depending on how we integrate all of these wireless devices 
that are about to spring up on us, it may become an issue again. If the 
wireless companies use their internal telephone addressing systems to deliver 
wireless data, rather than actual IP addresses (and even if they did use IP 
addressed, they'd still be using a private network behind a firewall), then 
it's still not very likely we'll "run out of" IPv4 addresses.

Just to put things in perspective... try doing a ping with the following script 
on a open-Internet-connected host:

   for k = 255 to 1

     for j = 255 to 1

       for i = 223 to 200

         ping -n 1 $i.$j.$k.1

       next

     next

   next

While this test is certainly not conclusive, and, you probably won't even have 
to go all the way through it.. what you can get from it is a rough idea of 
where in the Class C address space we still have available space.

And then remember that most of this address space is now being broken up into 
one of two realms:

      (a) DHCP for PPP connections (Dialup, ISDN, DSL)
      (b) 8-host subnets for LAN-Internet connectivity using NAT & Firewalls

Remember, also, that Classless addressing is now in place and functional, and 
as responsible organizations surrender (client) or reclaim (provider) unused 
Class B address space and reallocate it in much smaller chunks, the 
possibilities grow.

While we're functionally "out" of Class B address space.. try using the above 
script for i = 128 to 191 and see how many of those Class B subnets actually 
respond to an Internet ping -- and that will tell you how much Class B space is 
being wasted either:

   (a) not in use at all
   (b) in use behind firewalls, inappropriately
   (c) in use on non-Internet connected networks


To answer your basic question, though, how will we "convert" from IPv4 to 
IPv6.. it'll most likely happen from the top down. As I mentioned, the major OC 
backbone providers are already using IPv6. From there, it'll happen on a 
cooperative level from each tier to the next, first within an organizations 
internal structure, and then in cooperation with their "downstream" links.

Of course... as more and more upstream providers implement IPv6, and then 
middle guys, and ISPs internally, that also frees up more and more address 
space for the little guys... I suppose it's theoretically possible that doing 
so could create a situation in which we never do actually run out of IPv4 
addresses.

Which, of course, begs the question.. how will anybody actually FORCE the SOHO 
or small commercial office to do away with their NT 4 DHCP-based 8-port LAN?

--- 
 * Origin: lawrence@fido.eforest.net | The Enchanted Forest (1:106/6018)

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