Mailinglist Archive: opensuse (5130 mails)

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Re: [SLE] ipv6? -- IPv6 is actually a dream (and there's common FUD)
  • From: "Bryan J. Smith" <b.j.smith@xxxxxxxx>
  • Date: Sun, 28 May 2006 08:03:31 -0400
  • Message-id: <1148817812.2724.39.camel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
On Sun, 2006-05-28 at 09:40 +0200, Per Jessen wrote:
> Support for using IPv6 addresses everywhere - configuration etc.

Okay, there's a _lot_ of "FUD" out there about IPv6. Why? Because
people have _never_ used it. IPv6 was designed for
_less_administration_, and it _is_.

First off, every IPv6 system has an automatically configured LINK LOCAL
address. It's FE80::/64, with the lower 64-bits being based on the
48-bit IEEE802 MAC address.

E.g., my Ethernet MAC is:

My IPv6 LINK LOCAL address is:
^^^^ ^^ ^^ ^^ ^^^^ MAC Address
fe80::/64 (LINK LOCAL subnet)

If "LINK LOCAL" sounds familiar, it's because the IPv6 concept was
backported to IPv4 as well -- 169.254/16. *BUT* in IPv6, you _always_
have a "LINK LOCAL" address. I.e., the _local_, layer-2 IPv6 address is
_always_ "LINK LOCAL."

If you have a routed IPv6 address, then you have a _second_ IPv6 address
on a system. IPv6 was _purposely_ designed for 3 "context" IPs:
- LINK LOCAL (layer-2)
- SITE LOCAL (layer-3, internal -- deprecated, see below), NOW PRIVATE

Many _large_ and even _medium_ size enterprises are using IPv6 LINK
LOCAL and PRIVATE addresses. Why? Because it solves a _lot_ of issues.
Traditionally, interconnected enterprises use 1:1 NAT to hide their
schemes and avoid IPv4 address conflicts (i.e., I've worked in large,
interconnected defense and financial firms) -- but IPv6 handles it
_much_ better.

> Really? I wasn't aware of that. I though it worked the other way round.

Huh? _Every_ Linux distribution that enables IPv6 by default _also_ has
the system come up with a IPv4 address.

> So, if I were to get an IPv6 range from my provider

First off, you need to go research how IPv6 works. You _can_ use IPv6
_internally_, and then NAT/PAT IPv6 to IPv4 for the Internet. If you
are interconnecting enterprises, IPv6 typically _eliminates_ the
requirement for 1:1 IPv4 NAT.

Secondly, you have LINK LOCAL (layer-2) and PRIVATE (layer-3) addresses.
There _are_ reserved IPv6 ranges for private use. LINK LOCAL is an
absolute _dream_ to have on the same subnet.

> (there are some providers here that offer it),

Why are you talking "providers"? I'm _not_ talking about "providers"!
Anytime someone like myself talks of IPv6, _why_ do people think the

Oh, that's right, because they have _never_ used IPv6. ;-> IPv6 is a
_dream_ for enterprises! It was _not_ merely designed to address the
Internet, it was designed and _chosen_ by the IETF _because_ it solves
many issues for _enterprises_internally_!

> there's no reall need to worry?

Worry about what?

> Would people on plain IPv4 networks have access to e.g. my mail-server
> on IPv6 or would I need to provide some sort of gateway?

IPv4 maps into IPv6 and IPv6 maps into IPv4.
Again, _read_ up on IPv6 -- don't assume and spread FUD.

> Currently, I occasionally see AAAA records returned for some Swiss hosts
> - these I don't have access to without a IPv6-4 tunnel or something.
> (fortunately, they also have IPv4 addresses).

We *ARE* using IPv6 in the US at Fortune 100 companies, as well as
organizations that connect to them. Even if only the Internet2 is IPv6
publicly, IPv6 is very, very _common_ in the US.

It's one of the reasons why I'm pushing _hard_ to make IPv6 knowledge
_standard_ in the next round of LPI exam updates.

Bryan J. Smith Professional, technical annoyance
Americans don't get upset because citizens in some foreign
nations can burn the American flag -- Americans get upset
because citizens in those same nations can't burn their own

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