Excerpts from Tony Li on Thu, Apr 02, 2009 12:38:52PM -0700:
> The key point here is that the semantics of a namespace is only
> relative to the layer where it is applicable. The rest of the
> time, it's just opaque bits.
Yes and also, even within the scope of a namespace a particular name
might not be usable at a particular time or place, and it will be
"just opaque bits" there.
> Putting this all together, here's pass 3. Again, if I missed
> something or have misunderstood, please feel free to bring it up.
> The goal here is to reach rough consensus on these definitions and
> we're definitely close.
> ---------------------------------------------------------------------------
>
> locator A locator is a name that has topological sensitivity at a
> given layer and changes if the point of attachment at that
> layer changes.
I see how "at that layer" neatly takes care of the "might not change"
problem.
Now that we have the ideas worked out, this first sentence could
actually be reduced to
A locator names a point of attachment at a given layer.
"names a point of attachment" implies that the name changes if the
point of attachment changes, and that in turn implies that the name is
topology-sensitive. We could make those statements explicit but we
don't need to.
If we make them explicit, "topological sensitivity" needs tightening
up. A locator itself is not topologically-sensitive. It does not
change. Rather, an endpoint's association with a point of attachment
changes, so the association between the endpoint and point of
attachment name ("locator") changes. A locator does not have
topological sensitivity, the endpoint+locator association is.
So I wouldn't mind keeping things explicit but I suggest something
like:
A locator names a point of attachment at a given layer. If an
endpoint changes its points of attachment at that layer,
associations between the endpoint and locators will change.
> By default, a locator refers to layer 3.
> It is also possible to have locators at other layers.
> Locators may have other properties, such as their scope
> (local or global (default)) and their lifetime (ephemeral
> or permanent (default)).
Good
> identifier An identifier is the name of an object at a given layer;
> identifiers have no topological sensitivity, and do not
> have to change, even if the object changes its point(s) of
> attachment within the network topology. Identifiers may
> have other properties, such as the scope of their
> uniqueness (local or global (default)), the probability of
> their uniqueness (statistical or absolute (default)), and
> their lifetime (ephemeral or permanent (default)).
Good
> address An address is a name that is used as both an interface
> locator and an endpoint identifier.
Hmm ... this brings in "interface" and "endpoint". I suggest:
An address is a name that is used both as an IP-layer locator and an
IP-layer endpoint identifier.
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