Subject: RE: [Enum] How long will it take to update a NAPTR record?

From: "Pfautz, Penn L, ALVAP" <[email-masked]>
Date: Tue, 19 Mar 2002 12:24:11 -0500

It's nice to know about this mechanism, but does it change the view that at least some hold that ENUM is still not the place to handle realtime updates and that, at least for SIP, the ENUM should just hold a relatively static address of record?

Penn

-----Original Message-----
From: Patrik Fältström [mailto:[email-masked]]
Sent: Tuesday, March 19, 2002 10:05 AM
To: bill; [email-masked]
Subject: Re: [Enum] How long will it take to update a NAPTR record?

--On 2002-03-19 06.54 -0800 bill <[email-masked]> wrote:

> When an ENUM subscriber want to change his NAPTR record in real-time, 
> i.e. two mininute, like call transfer function provide by the telcom 
> system, how to reflect changes into the DNS servers?

The mechanism that can be used is called DNS Dynamic Update. Since an
interoperability test which was run in January this year, we know secure
dynamic update is possible with both the TKEY and SIG(0) mechanisms. It is
used at the IETF meeting here in Minneapolis for IPv4 addresses, and I for
example is using it myself (you can have a look at the IP-address for
zx81.paf.se which is the address my laptop have, or rather, last address it
had).

> There are many cases that need the ENUM DNS response in real-time to 
> satisfy the user's demand.

The update with dynamic update is instanatous, but, one still need to have
a TTL on the record itself. It is recommended that the TTL is around 60
seconds, and not shorter. That means that someone which queried for the
record 1 second before you changed the record will have the wrong data for
another 59 seconds.

This is the reason why I in 2916 wrote that DNS can not be used for "real
time updates".

It can be used if you with "real time" accept around 30 seconds of
instability for _that_ DNS record.

If you have suggested wording for 2916bis which clearifies this, please
send the information in my direction.

      paf

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---

From: Patrik Fältström <[email-masked]>
Date: Tue, 19 Mar 2002 13:18:56 -0600

--On 2002-03-19 12.24 -0500 "Pfautz, Penn L, ALVAP" <[email-masked]> wrote:

> It's nice to know about this mechanism, but does it change the view that
> at least some hold that ENUM is still not the place to handle realtime
> updates and that, at least for SIP, the ENUM should just hold a
> relatively static address of record?

Simple answer: No.

ENUM is not a replacement for SIP registrations or LDAP access to an SCP or
whatever. ENUM is a directory service where one can translate from an E.164
numbers to a set of URI's. That mapping should not change too often. "False
positives" regarding URI's MUST be accepted. With that I mean that an E.164
can map to a SIP URI, but noone might be registered at that address at the
time when the call setup happens.

  paf