RFC4291bis

[Brian E Carpenter <[e-mail]>]

Hi,

Assuming that we adopt draft-farmer-6man-exceptions-64
for the standards track or BCP, I suggest that we should
also update draft-ietf-6man-rfc4291bis as proposed below,
and plan for the two documents to be published as RFCs
simultaneously:

OLD:
   Interface Identifiers are 64 bit long except if the first three bits
   of the address are 000, or when the addresses are manually
   configured, or by exceptions defined in standards track documents.
   The rationale for using 64 bit Interface Identifiers can be found in
   [RFC7421].  An example of a standards track exception is [RFC6164]
   that standardises 127 bit prefixes on inter-router point-to-point
   links.

      Note: In the case of manual configuration, the Prefix and
      Interface Identifier can be any length as long as they add up to
      128.

NEW:
   Interface Identifiers for stateless address autoconfiguration
   are 64 bits long except if the first three bits
   of the address are 000, or when the addresses are manually
   configured, or by exceptions defined in standards track documents.
   The rationale for using 64 bit Interface Identifiers can be found in
   [RFC7421].  An example of a standards track exception is [RFC6164]
   that standardises 127 bit prefixes on inter-router point-to-point
   links. The relationship between prefix length and Interface Identifier
   length is discussed in [I-D.farmer-6man-exceptions-64].

      Note: In the case of manual configuration, the Prefix and
      Interface Identifier can be any length as long as they add up to
      128. In all cases, routing and forwarding processes must be
      designed to process prefixes of any length up to /128 [BCP198].

Comments:

1. This change makes it clear that the 64-bit IID length is for SLAAC.
2. It specifically send the reader to draft-farmer for details.
3. It underlines that routing must work for any length prefix.

    Brian