[131189] in North American Network Operators' Group
=?windows-1252?Q?Re:_IPv6_fc00::/7_=97_Unique_local_addresses?=
daemon@ATHENA.MIT.EDU (Owen DeLong)
Thu Oct 21 07:49:49 2010
From: Owen DeLong <owen@delong.com>
In-Reply-To: <AANLkTikhbiXoYTT=wryKBQUx464QDnuo724mYHykv7s_@mail.gmail.com>
Date: Thu, 21 Oct 2010 04:47:13 -0700
To: Ray Soucy <rps@maine.edu>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Oct 21, 2010, at 4:33 AM, Ray Soucy wrote:
> For for all intents and purposes if you're looking for RFC1918 style
> space in IPv6 you should consider the block FD00::/8 not FC00::/7 as
> the FC00::/8 space is reserved in ULA for assignment by a central
> authority (who knows why, but with that much address space nobody
> really cares).
>=20
> People may throw a fit at this, but as far as I'm concerned FD00::/8
> will never leave the edge of our network (we null route ULA space
> before it can leak out, just like you would with RFC1918 space). So
> you can pretty much use it has you see fit. If you want to keep your
> ULA space short there is nothing stopping you from using something
> like FD00::1 as a valid address.
>=20
I have no problem with that. My concern is that people will use FD00::/8
space in OTHER ways, and, since it has potential uniqueness if you
follow the RFC, it has greater potential for undesired success than
RFC-1918.
> You could embed your ASN into it or some other identifier if you want
> to avoid conflicts with other non-routed address space which should
> never enter or leave your network from the outside, but I'm just not
> seeing the practical application for this.
>=20
That only avoids conflicts if everyone within the networks to which
you may communicate uses the same system of uniqueness.
Think beyond today to the future possibility of M&A of other companies
also using ULA, etc.
Owen
> On Wed, Oct 20, 2010 at 5:48 PM, Jeroen van Aart <jeroen@mompl.net> =
wrote:
>> <IPv6 newbie>
>>=20
>> According to =
http://en.wikipedia.org/wiki/IPv6_address#Special_addresses an
>> fc00::/7 address includes a 40-bit pseudo random number:
>>=20
>> "fc00::/7 =97 Unique local addresses (ULA's) are intended for local
>> communication. They are routable only within a set of cooperating =
sites
>> (analogous to the private address ranges 10/8, 172.16/12, and =
192.168/16 of
>> IPv4).[12] The addresses include a 40-bit pseudorandom number in the =
routing
>> prefix intended to minimize the risk of conflicts if sites merge or =
packets
>> are misrouted into the Internet. Despite the restricted, local usage =
of
>> these addresses, their address scope is global, i.e. they are =
expected to be
>> globally unique."
>>=20
>> I am trying to set up a local IPv6 network and am curious why all the
>> examples I come accross do not seem to use the 40-bit pseudorandom =
number?
>> What should I do? Use something like fd00::1234, or incorporate =
something
>> like the interface's MAC address into the address? It'd make the =
address
>> quite unreadable though.
>>=20
>> Thanks,
>> Jeroen
>>=20
>> --
>> http://goldmark.org/jeff/stupid-disclaimers/
>> http://linuxmafia.com/~rick/faq/plural-of-virus.html
>>=20
>>=20
>=20
>=20
>=20
> --=20
> Ray Soucy
>=20
> Epic Communications Specialist
>=20
> Phone: +1 (207) 561-3526
>=20
> Networkmaine, a Unit of the University of Maine System
> http://www.networkmaine.net/
