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).
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.
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.
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>
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/