moving to IPv6

Phil Howard phil at
Sat Nov 1 15:07:13 UTC 1997

In the big spam thread, David R. Conrad writes...

> >Until IPv6 is widely used 
> Are any ISPs seriously considering deploying IPv6 in the forseeable future
> (e.g., what level of demand are ISPs in the US seeing for IPv6)?

What backbone providers offer it?

The transition to IPv6 is clearly going to have some difficulties.  We are
waiting on:

1.  Network equipment, with translation

2.  End user software

3.  Address space assignment

Either everything has to suddenly change to IPv6, or there has to be
translation tools in place.  The translation between the IPv4 subblock
of IPv6 will be easy.  But how much infrastructure will be ready to
go by the time customers have to use IPv6-only space?  Sure, proxy
servers can allow some access, but many people will want full access.

IPv6-only space is of less value than IPv4-private space until IPv6
becomes at least fully routeable over the Internet.  So the backbone
networks are going to have to take the lead to make it happen.  Even
when it is routeable, it has to work on all the ends, which will thus
have to have translations to make their IPv4 space appear as IPv6sub4

The best workable scenario I can see so far is one where IOS and other
routing software includes translation between IPv4 and IPv6s4 (I'll use
this term for the IPv4 equivalent sub block of IPv6 until someone tells
me there is a preferred term).  Backbones need to become IPv6 capable
first, including the MAEs and NAPs, then any IPv6 interfaces can reach
other IPv6.

Step two is to transition the IPv4 services, like major web sites, to
IPv6s4.  These services want to be full reachable, so as soon as we can
get users on IPv6, they will want to be on IPv6s4.  To get users into
the IPv6 space, it may require a pricing differential.  It will require
something.  We still have many users running Windows 3.1 and some even
running just DOS.

If ISPs drop the IPv6 price, they lose money.  They'd rather their
customers just stay on IPv4 (or IPv6s4) in that case.

If ISPs raise the IPv4 (or IPv6s4) price, they lose customers to some
other ISP that didn't.

Something is thus needed to encourage customers to move into IPv6 even
when it is fully routeable.

Since this is a network operation issue forum, the focus here should be
on how to handle this in the networks.  To me, this part doesn't seem
all too technically difficult, once the software is available to handle
it.  But just having IOS translating IPv4 <-> IPv6s4 is not enough.
We will need to manage the new IPv6 network.  All the various tools we
use will need to understanding IPv6 and how it it configured on the
network.  Routing will have to work right even during the transition
to this, which means BGP4v6 has to be there capable of understanding
IPv6 space at some point in time.

Routing issues will become different in IPv6.

If IPv6 allocations will have varying sizes like CIDR, then we might
continue to have issues of size based route filtering.  OTOH, with the
right methods of allocating IPv6 space, no one should ever have to come
back to get more space.  Eventually that should mean fewer routes as
IPv4/IPv6s4 closes down.  Route filtering should be encouraged on IPv4
space and prohibited on IPv6 space, at that point, IMHO.

Phil Howard | eat60me8 at eat1this at no5way37 at
  phil      | eat8this at stop6342 at w4x5y4z8 at
  at        | stop7it4 at die1spam at no1spam6 at
  milepost  | no75ads0 at no5spam4 at stop1736 at
  dot       | no23ads8 at stop6it3 at blow4me1 at
  com       | w0x5y9z7 at no9spam5 at stop5722 at

More information about the NANOG mailing list