On Oct 20, 2010, at 10:28 PM, Mark Andrews wrote: > > In message <4cbfc1d0.60...@apolix.co.za>, Graham Beneke writes: >> On 21/10/2010 02:41, Owen DeLong wrote: >>> On Oct 20, 2010, at 5:21 PM, Jeroen van Aart wrote: >>>> Someone advised me to use GUA instead of ULA. But since for my purposes th >> is is used for an IPv6 LAN would ULA not be the better choice? >>>> >>> IMHO, no. There's no disadvantage to using GUA and I personally don't think >> ULA really serves a purpose. If you want to later connect this >>> LAN to the internet or something that connects to something that connects t >> o something that connects to the internet or whatever, GUA provides >>> the following advantages: >>> + Guaranteed uniqueness (not just statistically probable uniquene >> ss) >>> + You can route it if you later desire to >>> >>> Since ULA offers no real advantages, I don't really see the point. >> >> Someone insisted to me yesterday the RFC1918-like address space was the >> only way to provide a 'friendly' place for people to start their journey >> in playing with IPv6. I think that the idea of real routable IPs on a >> lab network daunts many people. >> >> I've been down the road with ULA a few years back and I have to agree >> with Owen - rather just do it on GUA. > > Your throwing the baby out with the bath water here. > > ULA, by itself, is a painful especially when you have global IPv4 > reachability as you end up with lots of timeouts. This is similar > to have a bad 6to4 upsteam link. Just don't go there. > > ULA + PA works and provides stable internal addresses when your > upstream link in down the same way as RFC 1918 provides stable > internal addressing for IPv4 when your upstream link is down. > I keep hearing this and it never makes sense to me.
If your provider will assign you a static /48, then, you have stable addresses when your provider link is down in GUA. Who needs ULA? > You talk to the world using PA addresses, directly for IPv6 and > indirectly via PNAT for IPv4. These can change over time. > Or, if you don't want your IPv6 addresses to change over time, you can get a prefix from your friendly RIR. > Similarly, ULA + 6to4 works well provided the 6to4 works when you > are connected. When your IPv4 connection is renumbered you have a > new external addresses but the internal addresses stay the same. > That's a big "provided that"... One over which you have little or no control unless you are running a 6to4 gateway of your own and can guarantee that nobody pretends to be one that is topologically closer to any of your users. >> I was adding IPv6 to a fairly large experimental network and started >> using ULA. The local NREN then invited me to peer with them but I >> couldn't announce my ULA to them. They are running a 'public Internet' >> network and have a backbone that will just filter them. >> >> I think that the biggest thing that trips people up is that they think >> that they'll just fix-it-with-NAT to get onto the GUA Internet. Getting >> your own GUA from an RIR isn't tough - rather just do it. > > If your big enough to get your own GUA and have the dollars to get > it routed then do that. If you are forced to use PA (think home > networks) then having a ULA prefix as well is a good thing. > home network: 2620:0:930::/48 Try again. Owen
