Subject: RE: [Enum] draft-ietf-enum-operation-00.txt

From: "Vaudreuil, Greg M (Greg)" <[email-masked]>
Date: Thu, 20 Jul 2000 14:00:49 -0500

I will clarify the draft.

To start, DNS does not do badly when there is a low TTL for leaf-data, if
the leaf-data is infrequently accessed.  The odds of an individual phone
number leaf-node remaining in the cache of a given public DNS server
long-enough to be useful is very low.  There is limited locality of
reference for the PSTN.  Caching provides it's benefits higher in the
delegation tree.

The assertion that switch handles slow updates and the IN handles fast
updates confuses routing from delegation.  The routing between switches
changes slowly, but that is uninteresting given that we have ruled routing
out-of-scope.  The delegation of a phone number to a subscriber or block of
numbers to a company happens on the switch and happens "fast".  It is
reasonable for a phone number to become in-service within tens of minutes
from the time it is assigned to a subscriber, especially when correcting
previous provisioning errors.  Further, when porting numbers from one
provider to another, i.e., changing the DNAME or CNAME to point to another
domain, the change has to happen within a small service window.

If DNS deals with individual telephone numbers, as I understood the intent,
it must respond similarly fast.  That said, caching provides great value at
the e164.arpa, country code, and one or two more levels down depending on
national numbering plans.  IN the US, delegations of numbers are next
performed on the NPANXX boundary, a delegation that changes at fastest,
monthly, and normally only quarterly.  Within the 10,000 numbers within an
"exchange", the assignment changes almost minute-by-minute. 

I do not believe NAPTR provides any advantages unless you assume that
service-specific information for numbers within an entire sub-tree are
served off the same service-level directory.  We know that clearly does not
happen in a portability situation.

Greg V.

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Thursday, July 20, 2000 9:35 AM
To: 'Patrik Fältström'; [email-masked]
Subject: RE: [Enum] draft-ietf-enum-operation-00.txt

> -----Original Message-----
> From: Patrik Fältström [mailto:[email-masked]]

> >A URL for this Internet-Draft is:
> >http://www.ietf.org/internet-drafts/draft-ietf-enum-operation-00.txt
> 
> I object to the following parts in this draft:
> 
> >An
> >    effective ENUM service requires that DNS time-to-live 
> fields be set
> >    to an appropriate value consistent with the telephone number
> >    reassignment policies if the delegating authority.
> 
> Having a too low TTL is not appropriate in DNS. Therefore this draft 
> needs to be much more specific on when a number is possible to change 
> according to a "slow" or "fast" update. In normal telephony systems, 
> the switch itself (or accordingly) handles "slow" updates, and IN 
> systems handle the "fast" updates.
> 
> DNS is only suitable at this stage for "slow" updates.

I'd like this settled, myself. I've seen claims on this list that DNS can
now be updated in seconds, including master and slave servers. True? False?

> I claim DNS is not suitable for fast updates just because DNS do have 
> caching and do have delay between updates of slave servers from the 
> master servers. We should and can not fight that. If DNS one day can 
> handle "faster" updates, fine, but today we have a certain limit in 
> what speed DNS updates propagates over the Internet.

Bert
[email-masked]

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---

From: Patrik Fältström <[email-masked]>
Date: Fri, 21 Jul 2000 09:07:09 +0900

At 14.00 -0500 00-07-20, Vaudreuil, Greg M (Greg) wrote:
>Further, when porting numbers from one

 From my point of view, and the way I read your draft, the change of 
the CNAME and DNAME is something different than porting of the 
porting of a number.

I.e. I differ between the party which handles the redirect service, 
and the telco which handles the E.164 number. Those are two different 
entities.

When a customer changes the redirect service, you change the 
CNAME/DNAME/NS etc, but when changing telco (i.e. porting the number 
from one telco to another) you don't have to change the redirect 
service, but you update the content in the redirect service database.

This database can either be direct "tel" URIs in NAPTRs for the 
number, or changes in an LDAP database which the redirect service 
hosts. In both cases, porting of the telephone number from one telco 
to another means updating the NAPTR (in the case of a "direct" URI) 
or update of the LDAP database (in the case of an "indirect" URI).

Basically, I differ between the listing service for URIs, and who is 
responsible for the number.

    Patrik

---

From: Hong Liu <[email-masked]>
Date: Thu, 20 Jul 2000 22:16:35 -0400

Patrik, Greg and Albert,

I am reading your discussions with great interests. It seems to me that there
are a number of assumptions that need to be made explicit before we can
understand each other's viewpoint. The bottom line question is how delegation
of  the numbering space is done. So far, I have seen few discussions on this
topic. Maybe it is out of the scope of ENUM. But if we are to discuss
operational guidelines, then we need to find a good enough answer for this
basic question.

If we assume a single administrator for ENUM, at least on a national basis,
then what Patrik suggested may work. One possible way is to point the NAPTR
record to the common reference database of the administrator, or a finite
number of copies. (I am not saying this is a good solution.) If we assume a
distributed administration scheme like DNS today, then Greg's concern is quite
valid. Note that domain names are generally not portable, hence we need to come
up with special guidelines for using DNS to handle portable E.164 numbers.

So which model do we assume for ENUM, or both, or do we care?

I hope we can start discussing how delegation is done for ENUM, unless the WG
chairs declare that it is out of scope.

Cheers,

--Hong

---

From: Patrik Fältström <[email-masked]>
Date: Fri, 21 Jul 2000 13:06:34 +0900

At 22.16 -0400 00-07-20, Hong Liu wrote:
>Note that domain names are generally not portable, hence we need to come

This probably differs from country to country on how to do this.

   paf

---

From: Hong Liu <[email-masked]>
Date: Tue, 25 Jul 2000 20:40:08 -0400

> This probably differs from country to country on how to do this.

Patrik,

Can you elaborate on this a bit more? I would like to know some examples and
how this is done. Say my domain name is www.foo.xxx, whose DNS entry is hosted
by service provider A. Now I want it to be hosted by service provider B. Does
it mean that the top level domain xxx is jointly  maintained by both A and B,
each of which handles a (disjoint) subset of xxx? Thanks!

--Hong

---

From: Patrik Fältström <[email-masked]>
Date: Tue, 25 Jul 2000 18:13:57 -0700

>each of which handles a (disjoint) subset of xxx? Thanks!

You asked about ported numbers. That is something different from the 
case that you move your delegation (DNS resolution) from one party to 
another.

Now, if you have www.foo.xxx in your zone foo.xxx, which is hosted by 
A, and want it to be hosted by B, then you have to ask the one which 
hosts xxx to change the delegation of foo.xxx to B from A.

I.e. you have a C which hosts xxx which delegates the domain to first 
A, then B.

   paf