[ipv6-wg] /127 for point to point links

On Fri, 12 Feb 2010, Vegard Svanberg wrote:

> Hello. We've stumbled across a problem with a router manufacturer, which
> won't implement support for /127 prefix lengths. Now, we do have
> peering/transit partners using /127 on their p2p links. The result is
> that we either cannot peer with them, or will have to get new routers.
>
> RFC 3627 states that /127 is considered harmful, however I do feel this
> RFC confuse people since it doesn't propose a definite solution. It
> suggests a number of solutions and indicates using /64 is the right
> thing. I must say I strongly disagree on that conclusion. Wasting so
> much address space on point to point links just makes no sense to me.
>
> So I'm not sure what to do here. I have to convince someone; either our
> partners or the router manufacturer. I have the impression that /127 is
> used widely out there.

RFC 3627 is informational RFC. Does not describe any strict rules. Read 
the RFC and understand /127 is harmful only in certain cases: 
poin-to-point link + usage of subnet anycast. Other problems might exist 
as described in section 5.

Also Have a look at:

http://www.ietf.org/id/draft-kohno-ipv6-prefixlen-p2p-00.txt


Janos Mohacsi
Head of HBONE+ project
Network Engineer, Deputy Director of Network Planning and Projects
NIIF/HUNGARNET, HUNGARY
Key 70EF9882: DEC2 C685 1ED4 C95A 145F  4300 6F64 7B00 70EF 9882