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Re: [RRG] NAT-PT and other approaches to IPv6 adoption - Dual Stack Lite
[This is going a bit far afield from routing research topics, so it'll
be my last message on this thread]
Robin,
On Aug 4, 2008, at 7:40 AM, Robin Whittle wrote:
Currently, IPv6 is additive to the size of routing system, that is
IPv6
routes do not displace IPv4 routes. As such, it exacerbates the
routing
scalability problem.
I think they are two separate problems. IPv4 is a problem with 260k
advertised prefixes and IPv6 is nowhere near a problem with only a
thousand or so.
As far as I'm aware, they share the same resources.
Actually, it is a nice little informal protocol to enter "xxx sucks"
into Google and see what turns up. 30,800 pages for "Comcast
sucks" - but they have a huge number of customers, most of them
presumably happy.
Or, as in my case, there is no real alternative.
This gets into religion and questions of address
allocation policy that I suspect we don't want to get into here. If
you're interested in this sort of thing, I'd recommend ppml@arin.net
(and/or seeing a therapist).
Actually, I am trying to give up PPML.
Yeah, I bailed back in February. I have better walls to bash my head
against... :-)
Since IPv6 currently uses the same routing technology as IPv4, the
_Internet_ has a routing scalability problem.
These are two separate Internets.
Yes they are two separate Internets, but they are sharing the same
underlying resources (routers, bandwidth, engineers, etc).
I think the benefit of fixing IPv4 routing is primarily that a
billion or more people can continue for the foreseeable future using
the Internet the way they do today.
...
There is no prospect of moving everyone to IPv6 as far as I can see
- it is too disruptive.
Again, I'd argue a billion or more people simply don't care if they're
using IPv4 or IPv6. What they care about is getting to the services
and content they want/need. As I mentioned in my previous note, I
suspect the best case scenario we're looking at right now is for ISPs
migrate their own infrastructure over to IPv6 (tunneling IPv4 from
customer to edge through that IPv6 infrastructure), thereby allowing
them to reuse any IPv4 addresses they've used for internal
infrastructure for customer assignments. This has the side benefit of
allowing the ISP to provide IPv6 connectivity to their customers at no
(significant) additional cost. The economic incentives for an ISP to
migrate their infrastructure to IPv6 would come from avoiding the cost
of obtaining more IPv4 address space. "Dual stack lite" is a
variation of this, adding in the ability to do "carrier grade NAT"
within the ISP infrastructure. While some percentage of the existing
customer base won't like the implications of carrier-managed NAT,
there will likely be (extra cost) options that will keep those
customers mollified.
Of course, one of the problems with this scenario is that the IPv6
being deployed is straight "Deering IPv6", which means there will be
more "vast installed base" that will need to be dealt with if/when a
scalable IPv6 architecture is developed. Oh well.
I stand by all my arguments against the notion that ISPs will start
disconnecting their networks from certain portions of the Net, due
to marginal expense problems with running DFZ routers, due to desire
to urge people to use IPv6 or for any other purpose.
I'm not suggesting ISPs will filter for any other reason than self-
preservation. ISPs will filter out longer prefixes when they see
their infrastructure at risk. Having routers fall over, try to get
back up, and fall over again is not a lot of fun for anyone involved.
Given unconstrained routing system growth as implied by current
policies and technology and no deployable alternative, I'm not sure
what other options there are.
Regards,
-drc
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