Using /126 for IPv6 router links

Mark Smith nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org
Sat Jan 23 20:03:18 CST 2010


On Sat, 23 Jan 2010 20:08:05 -0500
Christopher Morrow <morrowc.lists at gmail.com> wrote:

> On Sat, Jan 23, 2010 at 7:52 AM, Mathias Seiler
> <mathias.seiler at mironet.ch> wrote:
> > Hi
> >
> > In reference to the discussion about /31 for router links, I d'like to know what is your experience with IPv6 in this regard.
> >
> > 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 ? ;)
> 
> <cough>draft-kohno-ipv6-prefixlen-p2p-00.txt</cough>
> 
> (<http://tools.ietf.org/id/draft-kohno-ipv6-prefixlen-p2p-00.txt>)
> 

<cough>Internet Draft</cough>

No disrespect to the people who've written it, however it's a draft at
this point, not an RFC.

The current IP Version 6 Addressing Architecture RFC (RFC4291) says,

"  For all unicast addresses, except those that start with the binary
   value 000, Interface IDs are required to be 64 bits long and to be
   constructed in Modified EUI-64 format"

If that draft is going to go anywhere, then I would expect there also
needs to be a new version of RFC4291.

> why not just ping your vendors to support this, and perhaps chime in
> on v6ops about wanting to do something sane with ptp link addressing?
> :)
> 
> -Chris
> 




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