Harald Tveit Alvestrand wrote:
But on mobility, I think we blew it.
I don't know if I agree with this -- most users that I
know are pretty mobile and certainly wireless. So I think
we do have some kind of a "Mobile Internet" already and
there's obviously more to come.
I do not want to comment on the specific mobility protocols.
But I'd like to suggest that we tend to think of Mobile
Internet issues in a too narrow sense. IP layer mobility
is just one part of the complete picture. What we really
need is an Internet that works transparently, seamlessly,
and securely in a world where connectivity is over wireless
and changing all the time. And yes, more work will be needed.
Here are some of the necessary components:
o Is our infrastructure ready to provide network access
to a large number of users, roaming across different
types of providers? Some of you may not be aware that
IETF provides much of the infrastructure components that
link layers use to grant access, such as AAA. And yes,
ubiquitous network access requires that providers get paid
for their service.
o What are the protocols that are used at the client end
for authentication and authorization? Are we stuck with
web-based logins? Or is 802.1X the answer, or cellular
network models?
o Does everything work when you combine them together?
Does it work with NATs, v4-v6 transition and
the simultaneous use of VPNs or multiple interfaces?
Do the protocols expect you to transition to IPv6
completely before you can begin deployment of the
additional features? Seems like there's a lot of work
to be done in this space...
o Do our layer 3 "control" components such as RD, ND,
and DHCP provide sufficient capabilities for, say,
detecting when an L3 change has occurred?
o Movement performance. There are many factors in
this -- I recently counted how many messages one
needs to attach to a commercial 802.11 network using
IPv6. The result was 24 messages, but I may have
missed some. Ongoing work in various IETF and IEEE
groups is making this faster, but work remains.
o Transport implications. How do transport layers and
applications react to underlying communications path
changes? If a mobility or multihoming protocol hides
topological movements from upper layers, does it still
need to tell TCP to do another slow start?
o Are all of our protocols capable of operating
in heterogeneous network conditions?
Many of the above things (though maybe not all) are
being addressed by different IETF groups. Just wanted
to point out that the issue is larger than Mobile IP.
--Jari
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