Private use of non-RFC1918 IP space (IPv6-MW)

Seth Mattinen sethm at rollernet.us
Wed Feb 4 20:00:38 CST 2009


TJ wrote:
>> Some devices will refuse to work if you subnet smaller than a /64. (Yes, poorly designed, etc.)
> 
> Actually, no - not poorly designed.  The spec says it must be a /64 (excluding those starting with 000 binary) so that is what devices (rightfully) expect.  Ref: http://tools.ietf.org/html/rfc4291#section-2.5.1 
> 

I was just trying to head off the flood of "poorly designed" comments
last time I said such a thing on a different list. ;)

I find /64 convenient because it ends on a nice boundary out of my /48
and for my purposes it's more than enough space. The only annoyance I've
come across was my Cisco devices will only accept an EUI-64 address as a
host address in an ACL. Not a big deal though.

~Seth




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