nanog mailing list archives
Re: IPV6 planning
From: Saku Ytti <saku () ytti fi>
Date: Sun, 6 Mar 2016 13:53:27 +0200
On 6 March 2016 at 03:08, Karl Auer <kauer () biplane com au> wrote:
To support SLAAC with prefix lengths other than 64 you would have to break numerous standards. RFC2464 is very clear on the matter, at least for Ethernet interfaces, though RFC 4862 is carefully non-committal.
Yes, SLAAC, 4862 clearly does not forbid it, and there is no technical reason. But as you state, 2464 does not specify other behaviour. Writing new draft which specifies behaviour for arbitrary size wouldn't be a challenge, marketing it might be.
From implementation POV, arbitrary prefix-size from 4862 is fairly
obvious and logical, and dictating 64 is very weird, with no obvious benefits at all. I suspect the 64 must have come into IPv6 ethernet standard before people thought of DAD, and assumption was uniqueness was guaranteed by use of BIA (HAH!), that's only background that I can imagine where mandating /64 might be remotely sane thought process. Post-DAD it's just artificial complexity which reduces expressiveness.
Even if the router supports it, as far as I know a standards-conforming host MUST ignore such prefixes for purposes of SLAAC on Ethernet.
I can't recall where it would be worded so harshly. But I agree that it's not good idea /NOW/ to use it, even if it works on some implementations. -- ++ytti
Current thread:
- IPV6 planning Laurent Dumont (Mar 05)
- Re: IPV6 planning Mark Tinka (Mar 05)
- Re: IPV6 planning Valdis . Kletnieks (Mar 05)
- Re: IPV6 planning Baldur Norddahl (Mar 05)
- Re: IPV6 planning Hugo Slabbert (Mar 05)
- Re: IPV6 planning Valdis . Kletnieks (Mar 05)
- Re: IPV6 planning Owen DeLong (Mar 07)
- Re: IPV6 planning Mark Tinka (Mar 05)
- Re: IPV6 planning Karl Auer (Mar 05)
- Re: IPV6 planning Saku Ytti (Mar 05)
- Re: IPV6 planning Karl Auer (Mar 05)
- Re: IPV6 planning Saku Ytti (Mar 06)
- Re: IPV6 planning Tore Anderson (Mar 06)
- Re: IPV6 planning Karl Auer (Mar 06)
- Re: IPV6 planning Baldur Norddahl (Mar 06)
- Re: IPV6 planning Karl Auer (Mar 06)
- Re: IPV6 planning Owen DeLong (Mar 07)
- Re: IPV6 planning Alarig Le Lay (Mar 07)
- Re: IPV6 planning Owen DeLong (Mar 07)
- Re: IPV6 planning Bjørn Mork (Mar 08)
- Re: IPV6 planning Enno Rey (Mar 08)
- Re: IPV6 planning Saku Ytti (Mar 05)
- Re: IPV6 planning Baldur Norddahl (Mar 07)