Note that some mobile (cellular) networks use cascaded, proxied, MIP
tunnels such that the the local L3 (network oriented) point of
attachment changes, even though the host does nto see that.
In general, different routing systems may require that the host visible
IP address changes at different granularities of motion. However, the
point with any locator is that there is some granularity of topological
change beyond which the locator must change. (If I understood Dow
properly Friday, this is the converse of the point he was making.
Routing systems may use identifiers with no topological significance in
all cases, in which case there is no need for locators. Or the routing
system may require that the locators not only exist, but change to
reflect every minute change of topological placement. Or they may
operate between those two extremes. What we know is that a locator, if
it exists in the solution, is something that changes when the
topological location of the located thing changes sufficiently.)
Yours,
Joel
Klaas Wierenga wrote:
Hi Tony,
Klaas Wierenga wrote:
locator A locator is a name that has topological sensitivity
and must
MUST? In for example mobile networks the layer 3 locator often doesn't
change if the point of attachment changes. So does "point of
attachment" refer to attachment at the layer the locator refers to?
change if the point of attachment changes. By convention,
a locator refers to layer 3 by default.
Ok, but in a mobile network, it's usually the L2 point of attachment
that's changing, not the L3 point of attachment. When you do change
that (i.e., roaming), then your locator is indeed changing and all sorts
of registration mechanisms are in place to update your locator.
agreed, does it get too complicated if you write:
"A locator is a name that has topological sensitivity and that must
change if the point of attachment (at the layer the locator refers to)
changes"
?
not sure myself, the definition gets a bit complicated, but I think it
is important to note that changing points of attachment on one layer
don't necessarily mean changing locators at another....
identifier An identifier is the name of an object; identifiers have no
topological sensitivity, and do not change, even if the
"do not change" -> "do not have to change"?
Sure. Someone might want to change their identifier at the time that
they roam for privacy reasons. That's certainly reasonable.
Right, that was my reasoning too, without the "do not have to" readers
may presuppose persistence.
Klaas
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