On 2010-01-07 19:30, Pekka Savola wrote:
> On Wed, 6 Jan 2010, Juergen Schoenwaelder wrote:
>>> 1) Mandate that the text representation is <SOMETHING>
>>> and never changes after this.
>>>
>>> 2) Mandate that the text representation is <SOMETHING>
>>> but take into account new WKPs.
>>>
>>> 3) Mandate that the text representation is <SOMETHING>
>>> but require that external mechanisms help recognize
>>> even dynamically assigned IPv4/IPv6 prefixes.
>>>
>>> 4) As above, but specify a mandatory external mechanism.
>>
>> My main interest is textual comparability of addresses coming from
>> potentially many different sources. If I can compare addresses safely
>> only if I know some context information communicated out of band or I
>> have to configure all sources to produce the same, I feel somewhat
>> uneasy. My preference thus is 1), I might be OK with 2) if the
>> frequency of the introduction of new WKPs is very small.
>
> While I like to see v4 address in a readable form when its used that
> way, I have to say I agree with Jürgen's concerns, especially if the
> algorithm was applied to opertor-specific prefixes as well (the tool
> would have to have this OOB intelligence).
>
> However, in some cases I'm not sure if comparison equality is really
> such a big deal. I don't think there's a way to satisfy both "embedded
> v4 readability" and "absolute comparability" so a tradeoff must be made.
>
> So, I'd actually suggest that we go for 1) or 2) but soften that a bit,
> like: "if it is known by some external method that the prefix includes
> an IPv4 address, the representation MAY print it in dotted decimal".
> With "external method" I'm thinking of either a command-line argument or
> application's own logic; I don't see how you could get that information
> "dynamically" so that it would be available to applications (for
> example, I don't see apps like that using DHCP information..).
Exactly. After all, this whole document is only a recommendation,
with strict backwards compatibility with the flexible format.
Brian
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