nanog mailing list archives
Re: IPv6 fc00::/7 — Unique local addresses
From: Ray Soucy <rps () maine edu>
Date: Thu, 21 Oct 2010 07:33:37 -0400
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). 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. 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. On Wed, Oct 20, 2010 at 5:48 PM, Jeroen van Aart <jeroen () mompl net> wrote:
<IPv6 newbie> 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. Thanks, Jeroen -- http://goldmark.org/jeff/stupid-disclaimers/ http://linuxmafia.com/~rick/faq/plural-of-virus.html
-- Ray Soucy Epic Communications Specialist Phone: +1 (207) 561-3526 Networkmaine, a Unit of the University of Maine System http://www.networkmaine.net/
Current thread:
- Re: IPv6 fc00::/7 — Unique local addresses, (continued)
- Re: IPv6 fc00::/7 — Unique local addresses Matthew Kaufman (Oct 20)
- Re: IPv6 fc00::/7 — Unique local addresses Mark Andrews (Oct 20)
- Re: IPv6 fc00::/7 — Unique local addresses Matthew Kaufman (Oct 20)
- Re: IPv6 fc00::/7 — Unique local addresses Mark Andrews (Oct 20)
- Re: IPv6 fc00::/7 — Unique local addresses Mark Smith (Oct 20)
- Re: IPv6 fc00::/7 — Unique local addresses Owen DeLong (Oct 21)
- Re: IPv6 fc00::/7 — Unique local addresses Matthew Kaufman (Oct 21)
- Re: IPv6 fc00::/7 ??? Unique local addresses Steve Meuse (Oct 21)
- Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Jeroen Massar (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Ray Soucy (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) William Herrin (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Joel Jaeggli (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Jack Bates (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Joe Hamelin (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Owen DeLong (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Owen DeLong (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Jack Bates (Oct 21)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) Joel Jaeggli (Oct 21)