WGLC ent-analysis-03: DSTM

[Pekka Savola <pekkas@netcore.fi>]

Hi,

(I'll put two most separable & possibly most discussable items in 
separate mails.)

In 8.1:

 Later in the transition process, after the enterprise has
 transitioned to a predominately IPv6 infrastructure, the architect
 should implement the Dual-IP Transition Mechanism [DSTM, DSTM+]. Or
 in the case of early deployment of IPv6-dominant networks DSTM can
 be used too.

and in 8.4:

DSTM [DSTM, DSTM+] is a useful tunneling mechanism for later in the
enterprise transition or deployment of IPv6-dominant network links
is desired. DSTM is to being submitted as an IETF Experimental RFC.

==> as it is, DSTM is a way too overloaded a mechanism to be referred to
without more disclaimers or description.  As it is, different people use
"DSTM" to mean at least the following things:
 a) v4-in-v6 tunnels
 b) automatically set-up v4-in-v6 tunnels
 c) automatic set up of v4-in-v6 tunnels when the host
    doesn't have v4 address and an app wants to create a v4 socket
 d) automatic monitoring and tear-down of said v4-over-v6 tunnel
    when the host detects it no longer needs the address/connectivity
 e) plus a number of extensions for even more colorful setups.

a) doesn't require DSTM; b) can be achieved using a tunnel broker; c)
does not require IETF interoperability (a local implementation choice
when/how to launch the v4-in-v6 activation).  d) could also be considered in
the same category (there are no bits in the wire or anything requiring
interoperability AFAICS on when the host removes the tunnel), though I'm
skeptical whether even providing that would be a good engineering choice.

My point is that I'm having hard time figuring out:
 1) what the document means when it's recommending DSTM, and
 2) based on my analysis above, I do not believe that DSTM (in the way that
    I think it's being referred to) is even needed.

Therefore my suggestion is to remove references to DSTM (preferable) or
greatly clarify the assumptions and the requirements on why it should
be necessary. (On the other hand, if the DSTM spec only described the
algorithms for doing c) and d) above in my list, I would have a lot fewer
concerns -- but as it is, I believe a reference would confuse more than
help.)

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