nanog mailing list archives
Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses)
From: Jeroen Massar <jeroen () unfix org>
Date: Thu, 21 Oct 2010 13:47:13 +0200
On 2010-10-21 13:33, Ray Soucy wrote: [..]
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.
And then your company gets bought and you need to merge networks, that is: renumber as they picked the same prefix. There is nothing wrong with RFC1918 per se, the big problem with it is that everybody else uses the same prefix, thus when you need to merge two networks you have collisions. I at one time also though that 'merging networks' and 'renumbering' is easy, till I heard stories from folks who where doing that for really large networks, who basically told that they where introducing 7+ layers of NAT to solve that issue, as renumbering is simply not doable if you have a global organization and if you are merging things like banks, for some magic reason they want to be able to talk to eachother. That is why there is ULA: low chance of collisions if one wants to stay in the RFC1918 mindset. And if you want a guarantee of no collisions: go to your favorite RIR and get a prefix from them. Greets, Jeroen
Current thread:
- Re: IPv6 fc00::/7 — Unique local addresses, (continued)
- 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)
- Re: Why ULA: low collision chance (Was: IPv6 fc00::/7 — Unique local addresses) William Herrin (Oct 22)