On Feb 16, 2017, at 13:25, otroan(_at_)employees(_dot_)org wrote:
On Feb 13, 2017, at 14:32, David Farmer <farmer(_at_)umn(_dot_)edu> wrote:
I have concerns with the following text;
IPv6 unicast routing is based on prefixes of any valid length up to
128 [BCP198]. For example, [RFC6164] standardises 127 bit prefixes
on inter-router point-to-point links. However, the Interface ID of
all unicast addresses, except those that start with the binary value
000, is required to be 64 bits long. The rationale for the 64 bit
boundary in IPv6 addresses can be found in [RFC7421]
The third sentence seems to limit exceptions to 64 bit IIDs to exclusively
addresses that start with binary vale of 000. There are at least two other
exceptions from standards track RFCs, that should be more clear accounted
for in this text. […]
[…]
The challenge is to find text that enforces the 64-bit boundary policy
(ignoring the technical arguments for a moment), and at the same time ensures
implementors do the right thing and make their code handle any prefix length.
Of course these are interdependent and doing the latter makes it harder to
enforce the first.
I propose the following:
IPv6 unicast routing is based on prefixes of any valid length up to 128
bits [BCP198]. However, as explained in [RFC7421], the Interface ID of
unicast addresses is generally required to be 64 bits in length, with
exceptions only provided in special cases where expressly recognized in
IETF standards track documents.
Trying to help out here.
--james woodyatt <jhw(_at_)google(_dot_)com <mailto:jhw(_at_)google(_dot_)com>>