[RRG] Mobility frequency

[Randall Atkinson <rja@extremenetworks.com>]

An earlier separate comment by Scott Brim triggered this thought...

Some in the IETF (historically at least, maybe not now) have wanted
to have IP mobility work well with many roaming events in 1 minute.

There is a useful and interesting NATO technical report [1] on IP mobility
that concludes that current IP mobility schemes don't really work well
for a device that moves its (layer-3) location more often than once
every few minutes.  Their conclusion, as I recall, was that when
considering mobility one ought to be trying to use Layer-2 mobility
(e.g. radios, satellites) for smaller and high frequency movements
(e.g. movements on the scale of seconds) and using layer-3 mobility
much less frequently (e.g. movements on the scale of several minutes
or longer).

That NATO report seems pretty sensible to me.  If one considers a
classical radio LAN, a node typically can move for a while/distance
before one needs to find and engage with a new uplink base station.
At least some mobile phone technologies also support the idea of
L2 mobility (e.g. between individual cells, but within one super-cell)
where an L3 handoff is only needed/applicable/useful between
super-cells.

The question of how much mobility a proposal ought to support,
if any at all, seems like a good one to ponder.

Yours,

Ran
rja@extremenetworks.com

[1] A search engine likely can find a PDF copy of this;
I don't have one to hand this minute.

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