On Mon, Jan 24, 2011 at 02:10:48PM +0100, Marco Hogewoning wrote: > > While reading up on IPv6, I've seen numerous places that subnets are now > > all /64. > > > > I have even read that subnets defined as /127 are considered harmful. > > RFC3627, with a lot of discussion in the IETF on this. See also > https://datatracker.ietf.org/doc/draft-ietf-6man-prefixlen-p2p/ > > > However while implementing IPv6 in our network, I've encountered several > > of our peering partners using /127 or /126 for point-to-point links. > > I personally don't any benefit in using /126 subnets. > > > What is the Best Current Practice for this - if there is any? > > > > Would you recommend me to use /64, /126 or /127? > > > > What are the pros and cons? > > >From an operational point of view there is a risk that be using /64 somebody > >can eat away a lot of memory by either scanning or even changing addresses. > >This is also described in the draft above... > > I would personally recommend to at least always assign the /64, even if you > would decide to configure the /127. RFC 3627 has been around long enough that > you will keep running into equipment or software that won't like the /127. In > which case you can always revert back to /64. > This will also allow you to use easy to remember addresses like ::1 and ::2, > saving you the headache of a lot of binary counting. > > Grtx, > > Marco
this results in -very- sparse matrix allocation - which is fine, as long as you believe that you'll never run out/make mistakes. personally, i've use /126 for the past 12 years w/o any problems. there was never supposed to be a hard split at /64 - it was done as a means to simplify autoconfig. --bill