Subject: [DMM] Comment on Req2 transparency for DMM

From: Alexandru Petrescu <[email-masked]>
Date: Tue, 31 Jul 2012 16:18:01 -0700

DMM coleagues,

I would like to comment on the REQ2 "Transparency to Upper Layers when
Needed".  The slide 4 of slides-84-dmm-1.pptx at
https://datatracker.ietf.org/meeting/84/materials.html says:

> The DMM solutions MUST provide transparency above the IP layer when
> needed. Such transparency is needed, when the mobile hosts or entire
> mobile networks [RFC3963] change their point of attachment to the
> Internet, for the application flows that cannot cope with a change
> of IP address. Otherwise the support to maintain a stable home IP
> address or prefix during handover may be declined.

Such transparency is needed indeed.  But I suggest moving the part "when
the mobile hosts or entire mobile networks" outside of this paragraph -
maybe as a common denominator as part somewhere earlier in the draft.

Most if not all requirements of DMM would be good to deal with mobile
hosts as well as groupings of computers (mobile networks).

This transparency aspect we discuss here is about the stack - its
effects are within the stack of a single computer.  When this
transparency is offered it means the existing applications which are
unaware of mobility events (changes in IP address) do not need to be
modified in order to deal with these mobility events.

There is another transparency aspect when we discuss outside a single
computer's stack - the mobility management performed by a Mobile Router
on behalf of LFNs in a moving network is also transparency - the LFNs
are not implementing any mobility software - the world looks fixed to them.

So this would require both transparency1 and transparency2.  I wonder
what happens in cases when only transparency1 or only transparency2 are
required and the other is relaxed - maybe a new scheme pops up.
Or maybe it doesnt make any sense...

Alex