Using /126 for IPv6 router links

Sun Jan 24 02:11:30 UTC 2010

On Sat, Jan 23, 2010 at 9:03 PM, Mark Smith
<nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org> wrote:
> 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.

absolutely. so... if it's of interest, speak up (on the v6 wg  mailing
list) or let the authors know.

> 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.

I believe the authors know this as well.

-Chris

>
>> 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
>>
>