Scott,
On 2009-02-22 09:42, Scott Brim wrote:
> Hi. A few questions ...
>
>> 3.1. A Mechanism Taxonomy
>>
>> In this taxonomy, solutions are grouped by the primary mechanisms
>> that they use to achieve their goals.
>
> I'm wondering, in the categories {transport, translation,
> encapsulation}, where would you put shim6? It's below transport.
> Would you say rewriting is translation? Would you say an addition of
> a header is an encapsulation?
>
>> 3.1.2. Translation
>>
>> Translation solutions are characterized by a translation
>> operation between an identifier to a locator and back to an
>> identifier as the packet traverses the network.
>
> Now that I've pondered this a little, I can't think of any approach
> that does that (translate from identifier to locator and back again).
> GSE only does it in one direction (->RLOC for source, ->ID for
> destination).
Shim6 does both translations in the case that ULID != RLOC, which
I think also answers your previous question. But certainly,
reversibility vs non-reversibility, and whether the translation
affects source, destination, or both, are facets of the taxonomy, I think.
Brian
GSE uses identifiers internally but does not need to
> translate outgoing destination addresses or incoming source addresses
> since they are already in RLOC form and must stay that way. NAT-based
> approaches and Six/One Router are also one-way: the local source
> address is translated to an RLOC when outgoing, and the destination
> address is translated to a local address when incoming. Also except
> for GSE and ILNP, the local "thing" is not an "identifier" in the
> sense that the term is used here, a topology-independent name of a
> single endpoint, or node ID. It is a locator with limited scope.
> Except in the case of GSE and ILNP it still names an attachment point
> and has topological significance.
>
>> 3.3.1. Strategy A
>>
>> Local routing is based on an address, which functions as a GUID,
>> SID component and local locator,
>
> Should this be an "and/or" or "or" instead of an "and"? Or is this
> supposed to be an in-line definition of "address"? A local locator is
> not necessarily also part of a session ID.
>
>> 3.3.2.2. Identifier variants
>>
>> B2a Each host has a single numeric identifer to which the
>> locators are attached. This identifier is used by the
>> layer-4/5 and higher protocols to compose the SID.
>>
>> B2b Each service provided by a host has a globally unique,
>> hierarchical character-string identifier to which the
>> locators are attached. Clients initiating communication
>> with that service negotiate a numeric SID which is unique
>> only within the scope of that service.
>
> In this section I don't see the relevance of "numeric" and
> "character-string". To the functions using these identifiers, they
> are just bits, regardless of what semantics a human might see in them.
>
> Scott
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