On 02/23/2017 07:43 PM, David Farmer wrote:
On Wed, Feb 22, 2017 at 10:16 PM, Lorenzo Colitti
<lorenzo(_at_)google(_dot_)com
<mailto:lorenzo(_at_)google(_dot_)com>> wrote:
Help he understand, then. There is widely-deployed code that assumes
that the interface ID is 64 and does not work on anything other than
64 bit prefix lengths. Currently that code is correct on all unicast
space. If you change RFC 4291, won't that code be incorrect?
OK, what if we said something like this;
IPv6 unicast routing is based on prefixes of any valid length up to
128 [BCP198]. However, all implementations of IPv6 are REQUIRED to
support an IID length of 64 bits, other IID lengths are OPTIONAL.
Subnet prefixes of /64 are RECOMMENDED for general purpose use,
subnet prefixes of /127 are RECOMMENDED for point-to-point router
links [RFC6164], other subnet prefix lengths are NOT RECOMMENDED,
as their use could be incompatible with some implementations of IPv6.
The rationale for the 64 bit boundary in IPv6 addresses can be found
in [RFC7421].
I'd remove a few sentences here, as in:
IPv6 unicast routing is based on prefixes of any valid length up to
128 [BCP198]. Subnet prefixes of /64 are RECOMMENDED for general
purpose use, subnet prefixes of /127 are RECOMMENDED for point-
to-point router links [RFC6164]. The rationale for the 64 bit
boundary in IPv6 addresses can be found in [RFC7421].
Thanks,
--
Fernando Gont
SI6 Networks
e-mail: fgont(_at_)si6networks(_dot_)com
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