In message <aanlktimsb6uj-jpoglg08q-rzdub-+c9c5kmzcktq...@mail.gmail.com>, Chri stopher Morrow writes: > On Sun, Oct 31, 2010 at 2:01 PM, George Bonser <gbon...@seven.com> wrote: > >> ula really never should an option... except for a short lived lab, > >> nothing permanent. > > > > I have a few candidate networks for it. =A0Mostly networks used for > > clustering or database access where they are just a flat LAN with no > > "gateway". =A0No layer 3 gets routed off that subnet and the only things > > talking on it are directly attached to it. > > why not just use link-local then?
If you had actually every tried to use link-local then you would know why you don't use link-local. > eventually you'll have to connect > that network with another one, chances of overlap (if the systems > support real revenue) are likely too high to want to pay the > renumbering costs, so even link-local isn't a 100% win :( > globally-unique is really the best option all around. 2^40 is 1099511627776. The chances of collision are so low that one really shouldn't worry about it. You are millions of times more likely of dieing from a asteroid 1-in-500,000[1]. If you merge thousands of ULA and don't consolidate then you start to have a reasonable chance of collision. Even if you do have colliding ULA prefixes you don't necessarially have colliding subnets when merging companies. Just allocate subnet randomly. It's not like 2^16 internal subnets is going to be a major routing problem. Mark [1] http://www.livescience.com/environment/050106_odds_of_dying.html -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
