[arin-ppml] IPv4 is depleted today - unrealistic statements about IPv6 inevitability

Howard, W. Lee Lee.Howard at stanleyassociates.com
Tue Sep 2 17:40:09 EDT 2008


> -----Original Message-----
> From: arin-ppml-bounces at arin.net 
> [mailto:arin-ppml-bounces at arin.net] On Behalf Of Robin Whittle
> Sent: Monday, September 01, 2008 9:42 PM
> To: ppml at arin.net
> Subject: Re: [arin-ppml] IPv4 is depleted today - unrealistic 
> statements about IPv6 inevitability
> Short version:   I think that the routing scaling problems will not
>                  be so severe as to lead to widespread IPv6-only
>                  adoption in the foreseeable future.

The people I speak to who operate large network think differently.

>                  The only routers which will be affected
>                  significantly by the growing number of DFZ routes
>                  will be those of transit providers and large ISPs
>                  where the routers have the highest number of
>                  neighbours.  I believe the operators of those
>                  routers will always find it better to upgrade or
>                  replace those routers, or to limit the number of
>                  neighbours they connect to, rather than drop some
>                  DFZ routes and therefore provide a second-rate
>                  service.

Those operators tell me there are no routers available or planned
that can handle the projected volume of routes and updates.  One
of the engineers for a router company you'll recognize told us about
a year ago that Moore's Law is approaching its limits regarding
routing scalability.

Look for "MR. LI".

The problem is not that transit providers and large ISPs don't want
to upgrade.  They do like to test their equipment before they put
it into production, but mostly, they like that equipment to exist
before they design their network around it.

Buy Jason Schiller a drink and ask him about "routing to the left."
>                  The most likely response to the IPv4 routing
>                  scaling problem and the related shortage of
>                  IPv4 space (caused largely by the current BGP
>                  only system being unable to slice the space
>                  up finely without bloating the DFZ routing table)
>                  is a Core-Edge Separation solution such as LISP,
>                  APT, Ivip or TRRP.  (Six/One Router is also a
>                  Core Edge Separation solution, but it only works
>                  for IPv6.)  This could be used as the basis for a
>                  new kind of IPv4 global mobility.

Many people have advocated here for a split between routing 
identifier and host identifier.  Most were discussing IPv6.  I
don't think this forum can help much in that debate, look over 
there --------------------->  IETF

[long version read and skipped, because the short version was so

> > will need IPv6 because other networks have run out of space, and 
> > because new deployments will have no choice.
> I don't think they will "need" IPv6, because IPv6 does not 
> give them what their customers need: IPv4 connectivity.

No, they want "Internet" connectivity.  

> I think the costs of running dual stack and making it work 
> would be pretty high.  There are plenty of apps which don't 
> work with IPv6 and there are few servers on IPv6.

Yep, we've gotten ourselves into a fine mess.

> But what sort of configuration work, software upgraded, 
> complexities, flakiness, support calls etc. would be required 
> for ordinary end-users to run their home networks dual stack 
> successfully?

Any OS released after 2006?

> too high.  All a competitor has to do is advertise full IPv4 
> support, rather than the second-rate "Dual Stack Lite" 
> approach, and it would be much more difficult to attract and 
> retain customers, including those who didn't need uPnP IGD.

Yep, it's a fine mess.

> It could get this bad if there is no widely deployed 
> Core-Edge Scheme to solve the routing scaling problem (LISP, 
> APT, Ivip, TRRP or Six/One Router).  I predict it would get 
> this bad and still it would be cheaper to keep using IPv4 
> directly, or via "Dual Stack Lite" than to try and sell 
> customers a pure IPv6 service which is for an Internet most 
> people don't connect to.

Er, why is that the only translation mechanism you're including?

> I think you are saying that while networks would be able to 
> get IPv4 space for quite a long time, as people split it more 
> finely and use it more intensively, that this will cause 
> widespread adoption of
> IPv6 (either without any IPv4 NAT arrangement, or with the 
> address-efficient "Dual Stack Lite" approach), because the 
> RIB or perhaps FIB limitations of DFZ routers cause many 
> networks not to carry the whole DFZ routing table.
> However, I have argued above that this is only likely to kick 
> in with the RIB of the transit routers with the most 
> neighbours - and that the providers who operate those will 
> always find it more viable to upgrade the router, or restrict 
> the number of neighbours, rather than offer incomplete connectivity.

Routing does not scale to 4 billion routes.  Don't know exactly
where hardware can't do it anymore.

If large network operators have to:
* spend millions for these new routers that I'm told don't exist, and 
* implement Dual Stack Lite, and 
* buy addresses from some market created out of a possible 
liberalized transfer policy, and
* NAT aggressively,

will that always be cheaper and provide better connectivity than 
IPv6 with translation technologies (tunnels, NAT-PT, teredo, 6to4, 
whatever: http://www.getipv6.info/index.php/Planning_IPv6_Deployment)


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