RE : [DNA] [Announce] DNA in IPv6 Goals I-D Update

[NJEDJOU Eric FTRD/DMR/REN <eric.njedjou@francetelecom.com>]

Hello JinHyeock, hello DNA,

I am having a couple of comments and remarks on the dna goal update
document.
I will quote the paragraph in the document then provide my remark
underneath

SECTION 1 Introduction 
"Today a link change necessitates an IP configuration change.
   Whenever the host detects that it has remained at the same link, it
   can usually assume its IP configuration is still valid.  Otherwise,
   the existing one is no longer valid and a new configuration must be
   acquired.  Hence a host only needs to check for link change to
   examine the validity of its IP configuration."

Comment: I am surprised at such an assumption. When a 802.22 STA
reassociates to a new AP, the IP subnet behind could possibly be the
same as that of the previous AP. Unless you define a link change
differently from the way people generally think of it.

SECTION 2 DNA in existing IPv6 systems
   "When a host changes its attachment point, for efficiency, a host
   should examine whether its IP configuration is still valid before
   initiating the process of acquiring a new IP configuration."

Comment: It should be precised that change of attachmment here refers to
change of link-layer attachment for clarity purpose

SECTION2 DNA in existing IPv6 systems
  "Link-layer hints are indications from lower
   layers that IP connectivity may have changed.  With suitable
   hysteresis, these hints may be used to initiate IP based reachability
   checks."

Comment: 
I do not agree with this definition of a link layer hint. 
Link layer hints could just indicate that a new link is present without
the IP configuration on current link being no more valid. I think there
is a confusion throughout this document between presence of a new link
and IP connectivity change. The first does not necessarily implies the
second.  

Link layer hints could also just indicate that an L2 handover has
happened without affecting the IP cnfiguration.

Actually, the only situation where link layer hints would strongly
advise about IP connectivity change will be the knowledge of a current
link going down while a new one is coming up.