Re: Internal WG Review: MIPv6 Signaling and Handoff Optimization (mipshop)

["James Kempf" <kempf@docomolabs-usa.com>]

Harald,

> I believe this is more correctly phrased as "If the mobile node no longer
> has link connectivity with the old subnet, any packets...."
>
> The obvious, but not always practical, solution to the problem (keeping
> both links during handover) is impliclity alluded to later, under "FMIPv6"
> (link preconfiguration), but is not mentioned explicitly anywhere.
>

"Not always practical" is the operative phrase here. I often hear this
solution proposed, unfortunately, to my knowledge, there is only one
wireless link protocol that supports multiple handover legs for IP today
(Flarion's OFDM protocol) and it is not a particularly big contender
commercially. In particular, the "soft handover" approaches of wCDMA and
cdma2000 don't work for this purpose, the handover legs are effectively
invisible at the IP layer.

> And of course the obvious common question: Where are the security
> requirements going to be developed....?
> (HMIPv6 introduces an obvious point for man-in-the-middle attacks, which
> may not even have to be on-link, for instance. So it's not security
> neutral....)
>

HMIPv6 has some security currently, not sure if it addresses your particular
concern since it's been a while since I looked at the document. The security
considerations in the current FMIPv6 draft are rather weak, there are some
approaches that have been discussed in the WG, most utilize IPsec in rather
cumbersome ways or depend on as-yet incomplete solutions like AAA key
exchange. Erik Nordmark mentioned the possibility of deferring specific
security solutions for FMIPv6 until and unless the work went from
Experimental to Proposed Standard, don't know whether that's a still viable
proposition, but I think it may be difficult to come up with anything clean
in the short time period during which this WG is expected to exist.

One of the intents of the WG is to get the work published as Experimental,
since it has been underway for 3 years now, then sort out integrating the
various bits of handover related technology that are being done in various
parts of IETF within the IP Mobility Research group in IRTF, filling in
holes where necessary and coming up with a clean, integrated handover
solution having strong security. That would then be a possible candidate for
PS.

            jak