IPv6 prefixes longer then /64: are they possible in DOCSIS networks?

Wed Nov 30 04:22:45 UTC 2011

A /112 is almost as bad for the ND attacks as a /64, so, I don't see any reason to use a /112 at all.

IMHO, the preferred link network sizes for IPv6 are, in order, /64, /127, /126, /112.

Since there's no downside to the first one so long as you take proper precautions about ND attacks,
most environments can stop there. If you are actually worried about ND, then consider /127. The
only reason to avoid it is if you have routers with code implementing RFCs that have been
deprecated for more than 5 years. Better to update your code, but, if you can't, move to /126.
It's a silly number, but, at least it's a little less silly than /112.

Owen

On Nov 29, 2011, at 9:00 AM, McCall, Gabriel wrote:

> Note that /127 is strongly discouraged in RFC5375 and RFC3627. 3627 suggests using /112 for router links, or /126 at the very most.
> 
> -----Original Message-----
> From: Fred Baker [mailto:fred at cisco.com] 
> ...
> I see no reason you couldn't use a /127 prefix if the link was point to point.
> ... 
> 