[131124] in North American Network Operators' Group
=?UTF-8?Q?Re=3A_IPv6_fc00=3A=3A=2F7_=E2=80=94_Unique_local_addresses?=
daemon@ATHENA.MIT.EDU (Jay Ford)
Wed Oct 20 17:54:50 2010
Date: Wed, 20 Oct 2010 16:54:43 -0500 (CDT)
From: Jay Ford <jay-ford@uiowa.edu>
To: Jeroen van Aart <jeroen@mompl.net>
In-Reply-To: <4CBF63BF.2000101@mompl.net>
Cc: NANOG list <nanog@nanog.org>
Reply-To: Jay Ford <jay-ford@uiowa.edu>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Wed, 20 Oct 2010, Jeroen van Aart wrote:
> According to http://en.wikipedia.org/wiki/IPv6_address#Special_addresses an
> fc00::/7 address includes a 40-bit pseudo random number:
>
> "fc00::/7 ? 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."
>
> 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.
Use the cool tool at http://www.sixxs.net/tools/grh/ula/ to generate a ULA,
then use it for local-scope stuff. Slick.
________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: jay-ford@uiowa.edu, phone: 319-335-5555, fax: 319-335-2951
