From: <otroan@xxxxxxxxxxxxx> To: "james woodyatt" <jhw@xxxxxxxxxx> Cc: <draft-ietf-6man-rfc4291bis@xxxxxxxx>; "6man WG" <ipv6@xxxxxxxx>; "IETF-Discussion Discussion" <ietf@xxxxxxxx>; <6man-chairs@xxxxxxxx> Sent: Friday, February 17, 2017 7:44 AM > James, > > 4291: > 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. > > 4291bis: > 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] > > Proposal: > 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 recognised > in IETF standards track documents. > > I think that's a good proposal. > Perhaps with s/is generally required to be/are/ Ole I would go further on the grounds that this is still somewhat woolly. I would say Proposal': 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 required to be 64 bits in length; any exceptions must be specified in IETF standards track documents. It would be nice to have something IANA-like with different categories of what can update what, with this being at the higher level, the bar set higher for an Interface ID that is not 64 bits in length, but when we say 'standards track' we are calling for IETF consensus and IESG approval and it is hard to see what more could be called for, unless we say that this is architectural and so the IAB must approve it! Tom Petch > Best regards, > Ole > >