Re: 6MAN WG Last Call: <draft-ietf-6man-prefixlen-p2p-00.txt>

[Pekka Savola <[e-mail]>]

On Thu, 18 Nov 2010, Bob Hinden wrote:
> as a Proposed Standard.  Substantive comments and statements of 
> support for advancing this document should be directed to the 
> mailing list.  Editorial suggestions can be sent to the authors. 
> This last call will end on December 6, 2010.

I think the document needs work before it can be progressed. I do 
think this is a useful document (esp section 5.1 and 5.2).

The document should probably mark in its header RFC3627 obsolete, and 
mark itself as updating RC4291 (in practise Section 6 appears to do 
so).

Section 3, second paragraph does not reflect operational reality:

    For the purposes of this document, an inter-router point-to-point
    link is a link to which only two routers and no hosts are attached.
    This may include Ethernet links which are configured to be point-to-
    point.  In such cases, there is no need to support Neighbor Discovery
    for address resolution, and other general scenarios like the use of
    stateless address autoconfiguration are not relevant.

.. Please educate me on implementations that allow you to configure 
Ethernet link as point-to-point (in ifconfig IFFLAGS sense).

Section 4 does not describe the root cause (i.e. why /127 can be used 
successfully) i.e. that Subnet-router anycast addresses have not been 
implemented, or if they have been implemented, it has been done only 
with prefixlen=64 (similar to what was suggested in RFC3627 point 4):

4. Problems identified with 127-bit prefix lengths in the past
..
    Though the analyses in the RFCs are correct, operational experience
    with IPv6 has shown that /127 prefixes can be used successfully.

Section 6 should probably be renamed "Conformance" instead of 
recommendations (it's giving out MUST advice etc.)

I think there will be pushback on the brief security considerations 
section.

I think the document could be clearer wrt terminology of 
'point-to-point'.  In some context it means a link where there should 
be only two nodes connected.  In some contexts it means a link which 
by its nature can only have two nodes connected and does not perform 
neighbor discovery.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings