On Jan 24, 2010, at 4:29 PM, Nathan Ward wrote: > > On 24/01/2010, at 5:28 PM, Leo Bicknell wrote: > >> In a message written on Sat, Jan 23, 2010 at 01:52:21PM +0100, Mathias >> Seiler wrote: >>> I use a /126 if possible but have also configured one /64 just for the link >>> between two routers. This works great but when I think that I'm wasting >>> 2^64 - 2 addresses here it feels plain wrong. >>> >>> So what do you think? Good? Bad? Ugly? /127 ? ;) >> >> I have used /126's, /127's, and others, based on peers preference. >> >> I personally have a fondness for /112's, as it gives you more than >> 2 addresses, and a DNS bit boundary. >> >> For all the pontification about how there are enough /64's to number >> all the grains of sand, or other nonsense, I think that ignores too >> much operational information. >> >> rDNS is important, and becomes harder in IPv6. Making it easier >> is importnat. >> >> Having a scan of a /64 fill your P2P T1 is poor design, all because >> you assigned 2^64 addresses to a link that will never have more >> than 2 functional devices. >> >> Most importantly, we should not let any vendor code any of these >> into software or silicon, in case we need to change later. > > I too prefer /112s. I can take the first /64 in any assignment or allocation > and set it aside for networking infrastructure. > The first /112 is for loopbacks, the remaining /112s are for linknets. > > Then I can filter this /64 at my border, and it's easy. > > You can do the same thing with /64 linknets, but then you have to set aside a > block of them, and that might get hard if you have a /48 or something. Maybe > not. What if you have a /56? > If you have link nets, you probably shouldn't have just a /48 and you CERTAINLY shouldn't have just a /56.
Owen