Subject: AW: AW: AW: [Enum] Fwd: [Sipping] I-D ACTION:draft-ietf-sipping-e164-03.t xt

From: "Martin Streller" <[email-masked]>
Date: Tue, 8 Jul 2003 14:22:58 +0200

Hello, please see below,
Btw, with customers I also include institutions, like Marian.
Martin

    >>>>> "Marian" == Marian Durkovic <[email-masked]> writes:

        Marian> The approach of having one record per every PBX extension
        Marian> is perhaps usable in trials, but it does not scale. Our
        Marian> institutions typically have 3-digit extensions, the larger
        Marian> ones 4-digit extensions. Having this in mind you can
        Marian> easily find yourself in the situation, where e.g. 300
        Marian> customers generate as much as 1 million records. If
        Marian> there's 1 million records in top-level domain, you have 1
        Marian> milion customers to cover the costs. But what will be the
        Marian> cost per customer, if the number of customers is 300 ?

    I don't understand the point you're trying to make here. You seem to
    be saying something "won't scale" for 300 names but somehow scales
    just fine for 1 million names. I'm confused. And you've still to
    explain why provisioning NAPTRs for each number -- something you said
    was trivial -- couldn't be done and why a wildcard RR was the only
    possible solution to the problem you're trying to solve. Despite what
    you said earlier, this still looks to me that the wildcard has been
    suggested as a kludge to work around a provisioning problem. And a
    straightforward one at that.

        Marian> The approach with wildcards generates only 300 records per
        Marian> 300 customers.  This is huge difference certainly worth
        Marian> inverstigating.

    It has even bigger implications which you don't seem to appreciate.
    You've not given any convincing explanation why a wildcard RR is the
    only solution and why alternatives are not viable. Please provide that
    explanation. 

        >> Patrik Faltstrom wrote: The only place they are used is when
        >> the MX record refer to a gateway (to X.400 or UUCP) where the
        >> other side of the gateway is managing a number of (sub-)
        >> domains, and it is impossible to point all these domains in DNS
        >> with individual MX records to the media gateway.

        Marian> You hit the nail. We need to do similar thing - redirect
        Marian> all voice traffic to a VoIP gateway connected to PBX with
        Marian> many many extensions.

    Well this is a perfect example of why DNS wildcards provide the wrong
    answer to the wrong question. You're assuming that the only use of
    ENUM for some range of numbers would be to contact a VoIP gateway. 
[Martin]
Within our customer range, eventually interested in ENUM, the VoIP gateway
centric view is the only that makes sense. ENUM is for them interesting as
a kind of Least-Cost-Routing. Firstly try to call by means of ENUM/H.323, secondly
call via the costly PSTN. All this is handled within the VoIP gateway and applies 
for outbound calls. 
Of course do they want to be reachable inbound via ENUM/H.323, as well. 
Without devoting man-power, without bearing additional costs. 
Such customers typically do already have a VoIP gateway and a dial-up connection
to the Internet. They typically do not have a DNS server. So, what's more elegant
than submitting a single NAPTR RR that is hosted elsewhere and covers the PSTN root number of 
this company ?

    This
    cannot be guaranteed. What happens when the owners of (some of) those
    numbers want additional NAPTRs for other services? 
[Martin]
Our customer community did not wait for ENUM in its entirety. They're interested in
telephone-related aspects. So, no additional NAPTRs wanted here.
    
    What if they *don't*
    want to use this default VoIP gateway? 
[Martin]
They want, because they typically have a single one.

    Or can't use it. What happens
    with numbers that are not in service? 
[Martin]
A call attempt is being made and the call cannot be established. Very much like in the
PSTN world.
    
    Should applications which look
    these up be pointed at the VoIP gateway regardless? 
[Martin]
Yes.

    That's what you'd
    get with a wildcard. 
[Martin]
And exactly this is welcome.

    Maybe it would be better to get an NXDOMAIN
    response from the DNS. Which of course you can't get if there's a
    wildcard RR. The same goes for numbers that are invalid because they
    don't have the correct number of digits. 
[Martin]
As I stated earlier, there is no problem with numbers that are incomplete 
or "overdialled". If e.g. a call with an incomplete number arrives at a VoIP gateway,
the gateway accepts the call but does not send back an ALERT. Through the, from now on,
established call signalling session the call originator gets the opportunity to submit
further digits without consulting the ENUM track anymore. This is called 
overlapped-dialling.

    What if some of the active
    numbers must not be used for VoIP because they're bound to things like
    a fax machine or a modem? 
[Martin]
Fax over IP (FoIP) is already happening today. Everything that applies for VoIP can
be taken into account for FoIP. Again no problem here. Modem over IP may be not that
widespread, however the same point of view here.

    What if you need to introduce additional
    VoIP gateways for some or all of the numbers?
[Martin]
Hmhh, not sure what you mean, do you refer to load balancing of inbound calls ?
If yes, this would mean a totally different thread.

    BTW, what you're proposing is NOT similar to the scenario Patrik
    outlined at all. You're talking about a known, well-defined, if large,
    name space: a range of telephone numbers. It is possible to enumerate
    all the domain names that exist there. In fact, it's trivial. In the
    scenario Patrik explains the wildcard MX record covers a name space
    that is not known and cannot be enumerated because it is somewhat
    unstructured and dynamic.
[Martin]
If I could go to my NAPTR RR hoster's website and could enter:
- my root number as +49 703173009 
- my desired number range like: from 10 to 99 
- my h323 URI
then I'd be happy. I wouldn't insist on wildcards.
In other words I want to to be able to do it one time for my whole
number range within 10 minutes and then forget it.

        >> Michael Haberler wrote: Or do you propose to have a wildcard in
        >> the zone, and have the server interpret it differently - i.e
        >> giving a matching non-wildcard response?

        Marian> This is how wildcards work _now_ with standard DNS - they
        Marian> are internal to the host running the DNS daemon. The
        Marian> end-user's resolver has no way to tell, if the response is
        Marian> based on wildcard or exact record, since the response is
        Marian> formulated as exact match in both cases. We can certaintly
        Marian> improve the default wildcard behaviour with more
        Marian> sophisticated record synthesizing, in order to get rid of
        Marian> common problems with classic wildcards,

    Sorry, you can't change the semantics of DNS wildcarding without a
    wholesale protocol rewrite. And somehow keeping backwards
    compatibility with the installed base. Please show how you intend to
    do this. For bonus points, get the DNS WGs to adopt your proposal. :-)

        Marian> but I think we really need the capability for one-to-many
        Marian> conversion in ENUM DNS.

    I've not seen any justification for this so far though I accept it
    might be useful. Perhaps you could provide some examples?

[Martin]
You been getting the examples from Marian and me.

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---

From: Jim Reid <[email-masked]>
Date: Tue, 08 Jul 2003 08:19:03 -0700

>>>>> "Martin" == Martin Streller <[email-masked]> writes:

    Martin> If I could go to my NAPTR RR hoster's website and could
    Martin> enter: - my root number as +49 703173009=20 - my desired
    Martin> number range like: from 10 to 99=20 - my h323 URI then I'd
    Martin> be happy. I wouldn't insist on wildcards.  In other words
    Martin> I want to to be able to do it one time for my whole number
    Martin> range within 10 minutes and then forget it.

In other words, this really is a provisioning problem after all. It
shouldn't need to involve DNS wildcards.

    Jim>     I've not seen any justification for this so far though
    Jim> I accept it might be useful. Perhaps you could provide
    Jim > some examples?

    Martin> You been getting the examples from Marian and me.

Er, no. With respect, the example you've given -- it seems to be the
same one from both you and Marian -- describe a provisioning issue
that can be kludged around with DNS wildcarding. This is unlikely to
be a justification for deploying wildcards that most DNS people would
understand and endorse. If you recall Patrik's earlier remarks, these
can be paraphrased as "show why there's no other option to using
wildcards". This remains to be shown IMO.

NB: I've taken [email-masked] off this thread to keep Lawrence
happy. And I've changed the Subject: header to something more
meaningful too.