One document matched: draft-bellis-enum-send-n-00.xml
<?xml version='1.0' ?>
<!DOCTYPE rfc SYSTEM 'rfc2629.dtd'>
<rfc ipr="full3978" docName="draft-bellis-enum-send-n-00">
<?rfc toc='yes' ?>
<?rfc tocompact='no' ?>
<?rfc compact='yes' ?>
<?rfc subcompact='yes' ?>
<?rfc sortrefs='yes' ?>
<?rfc symrefs='yes' ?>
<front>
<title abbrev="Send-N Enumservice"> IANA Registrations for the 'Send-N' Enumservice</title>
<author initials="R.P." surname="Bellis" fullname="Ray Bellis">
<organization>Nominet UK</organization>
<address>
<postal>
<street>Edmund Halley Road</street>
<city>Oxford</city>
<code>OX4 4DQ</code>
<country>United Kingdom</country>
</postal>
<phone>+44 1865 332211</phone>
<email>ray.bellis@nominet.org.uk</email>
<uri>http://www.nominet.org.uk/</uri>
</address>
</author>
<date day="2" month="April" year="2008"/>
<area>RAI</area>
<workgroup>ENUM -- Telephone Number Mapping Working Group</workgroup>
<keyword>ENUM</keyword>
<keyword>Enumservice</keyword>
<keyword>Send-N</keyword>
<abstract>
<t>This document requests IANA registration of an Enumservice 'Send-N' and extends the
definition of the 'pstndata:' URI scheme. This service allows more efficient support for
overlapped dialling in E.164 Number Mapping (ENUM) enabled applications.</t>
</abstract>
</front>
<middle>
<section anchor="intro" title="Introduction">
<t><xref target="I-D.ietf-enum-3761bis">E.164 Number Mapping (ENUM)</xref> uses the <xref
target="RFC1035">Domain Name System (DNS)</xref> to refer from <xref target="E.164">E.164
numbers</xref> to <xref target="RFC3986">Uniform Resource Identifiers (URIs)</xref></t>
<t>Most SIP devices and cellular devices require the user to dial a complete telephone number
and then press a 'send' or 'dial' button to initiate dialling. This contrasts with the
typical operation of PSTN telephones where dialled digits are sent to the network operator
as soon they are dialled and the call is initiated as soon as the network recognises that a
complete number has been dialled. This PSTN model for dialling is known as "overlapped
dialing".</t>
<t> Currently to support overlapped dialling an ENUM application would need to perform an ENUM
lookup as each and every digit is dialled. This would impose a significant burden on the
ENUM DNS servers and could also affect call setup time.</t>
<t> By storing additional information within the ENUM database about the structure of the
local numbering plan it is possible to provide hints to such an application that will allow
it to skip unnecessary per-digit ENUM lookups.</t>
<t> This additional information is encoded within NAPTR records since this avoids the need for
ENUM applications to issue multiple DNS requests with varying QTYPEs depending on the type
of information being looked up. To differentiate NAPTR records containing 'Send-N' data from
other types of NAPTR record it is necessary to create a new Enumservice which must be
registered with IANA.</t>
<t><xref target="I-D.ietf-enum-cnam"/> registers the 'cnam' Enumservice for PSTN data with
type 'pstndata' and a specific 'cnam' subtype for Calling Name Delivery. It also registers
the 'pstndata' Uniform Resource Identifier (URI) scheme. Both the Enumservice and the URI
scheme documented therein are intended to be extensible to represent other PSTN related
data.</t>
<t> This document therefore requests the registration of a new Enumservice subtype for
'Send-N' and extends the definition of the 'pstndata:' URI scheme.</t>
</section>
<section anchor="terminology" title="Terminology">
<t> The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD
NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as
described in <xref target="RFC2119">RFC 2119</xref>.</t>
<t> A "full ENUM record" is an RRset containing NAPTR records about a complete E.164 telephone
number.</t>
</section>
<section anchor="regenum" title="ENUM Service Registration for "Send-N"">
<t>The following template contains information required for the IANA registrations of the
'Send-N' Enumservice:</t>
<t>Enumservice Name: Send-N</t>
<t>Enum service Class: Ancillary Application Enumservice</t>
<t>Enumservice Type: pstndata</t>
<t>Enumservice Subtype: send-n</t>
<t>URI Schemes: pstndata:</t>
<t>Functional Specification: <list style="empty">
<t> This Enumservice indicates that the resource record contains information that
describes the structure of the local E.164 numbering plan below this point. </t>
</list>
</t>
<t>Security Considerations: see <xref target="security"/></t>
<t>Intended Usage: COMMON</t>
<t>Author: Ray Bellis <mailto:ray.bellis@nominet.org.uk> </t>
</section>
<section anchor="scheme"
title="IANA Registration Template for URI scheme "pstndata:"">
<t>URI scheme name: pstndata</t>
<t>Status: provisional</t>
<t>URI scheme syntax: (in ABNF <xref target="RFC5234"/>) <figure>
<artwork align="center">
<![CDATA[
pstndatauri =/ ( "pstndata:" sendndatatype )
sendndatatype = "send-n/" digitsmin [ "-" digitsmax ]
digitsmin = e164digitcount
digitsmax = e164digitcount
e164digitcount = %x30-%x39 / (%x31 %x30-%x35)
; 0 - 15 digits, per E.164
]]>
</artwork>
</figure> where 'pstndatauri' is imported from <xref target="I-D.ietf-enum-cnam"/>
</t>
<t>URI scheme semantics: The URI contains information that describes the structure of the
local E.164 numbering plan. This information is interpreted to be relative to the domain
which contained the NAPTR RR which in turn contained this URI in its 'regexp' field.</t>
<t>Encoding considerations: None, all valid characters are in US ASCII</t>
<t>Applications: <xref target="I-D.ietf-enum-3761bis">ENUM</xref></t>
<t>Interoperability considerations: none</t>
<t>Security considerations: see <xref target="security"/></t>
<t>Contact: Ray Bellis <mailto:ray.bellis@nominet.org.uk> </t>
<t>References: <xref target="I-D.ietf-enum-cnam"/></t>
</section>
<section anchor="description" title="Description">
<t>The records described here contain meta-information about an ENUM database - specifically
the depth (or range of depths) in the DNS tree below the current record at which full ENUM
records may be found, as per the local numbering plan.</t>
<t> Note that gaps in the E.164 numbering plan are not represented by this data. The 'Send-N'
data only indicates the _potential_ presence of numbers, not their absence. The details of
how the absence of ENUM records should be represented (e.g. for invalid or unallocated
numbers) are not addressed in this document.</t>
<t> The 'digitsmin' field of the data MUST correspond to the minimum number of additional
digits to be dialled, relative to the current record, which might result in reaching a full
ENUM record in the ENUM database.</t>
<t> It is RECOMMENDED that the 'digitsmax' field also be supplied and where supplied it MUST
correspond to the maximum number of additional digits that might be valid in the relevant
numbering plan. If the 'digitsmax' field is omitted this represents that the information is
unknown and MUST NOT be assumed to be the same as 'digitsmin'.</t>
</section>
<section anchor="examples" title="Example">
<t>An example ENUM entry containing 'Send-N' data looks like: <figure>
<artwork align="center">
<![CDATA[
$ORIGIN 5.6.8.1.4.4.e164.arpa.
@ IN NAPTR ( 100 10 "u"
"E2U+pstndata:send-n"
"!^.*$!pstndata:send-n/5-6!" .
)
]]>
</artwork>
</figure> This record indicates that between 5 and 6 additional digits are required to reach
any valid E.164 number beginning +441865 according to the local numbering plan.</t>
<!-- <t>NOTE - As described above this record does not indicate that all possible 5 or 6 digit
suffixes appended to +441865 will result in a valid ENUM lookup - numbers may be missing
from the ENUM database either because they are not in use or simply because they are not
registered for ENUM service.</t> -->
<t>Having received the NAPTR record from the previous example, the application might
subsequently receive the five additional digits "33221". Based on the previously received
record the application knows that it need not perform any ENUM lookups for each of the next
four digits, but on receiving the fifth it then performs another ENUM lookup, returning the
record below:<figure>
<artwork align="center">
<![CDATA[
$ORIGIN 1.2.2.3.3.5.6.8.1.4.4.e164.arpa.
@ IN NAPTR ( 100 10 "u"
"E2U+pstndata:send-n"
"!^.*$!pstndata:send-n/1-1!" .
)
]]>
</artwork>
</figure> This data indicates that exactly one further digit needs to be dialled before a
full ENUM record might be returned. </t>
</section>
<section anchor="dns" title="DNS Considerations">
<t>These records MUST NOT be used with DNS wildcards since DNS wildcards can represent an
arbitrary number of labels (or digits, in the ENUM case) and the data in a 'Send-N' record
is specific to an exact position in the ENUM tree</t>
<t>These records are mostly likely to be used in intermediate records in the ENUM database,
although in countries (such as Austria) that use open numbering plans it might be possible
to find both full NAPTR records and 'Send-N' NAPTR records in the same RRset.</t>
<t>An example of this is where a company switchboard might be reached by dialling the main
number and extensions are reached by dialling additional digits. In that case the
country-level administrator would maintain 'Send-N' records that describe the national
dialling plan, but end user ENUM registrations could supply additional 'Send-N' records that
describe their internal numbering plan.</t>
</section>
<section anchor="security" title="Security Considerations">
<t>This Enumservice and URI scheme were originally designed for use on a large private ENUM
database, where no security issues are believed to exist.</t>
<t>Security issues resulting from use of this data in public ENUM database where delegations
are made to third parties have not been assessed in detail, however it is believed that no
new security or privacy issues would arise from the use of this data.</t>
</section>
<section anchor="iana" title="IANA Considerations">
<t>This document requests the IANA registration of the Enumservice 'Send-N' with Type
'pstndata' and Subtype 'send-n' according to the definitions in this document, <xref
target="I-D.ietf-enum-enumservices-guide">RFCxxxx</xref> and <xref
target="I-D.ietf-enum-3761bis">RFC3761bis</xref>. The required template is contained in
<xref target="regenum"/>. </t>
<t>This document requests an update to the IANA registration of the URI scheme 'pstndata:'
according to the definitions in this document and following the process described in <xref
target="RFC4395"/>. The required template is contain in <xref target="scheme"/>.</t>
</section>
<section anchor="changelog" title="Change Log">
<t>[Note to editors: This section is to be removed before publication - XML source available
on request]</t>
<t>draft-bellis-enum-send-n-00 <list>
<t>initial draft</t>
</list>
</t>
</section>
<section anchor="ack" title="Acknowledgements">
<t> The author would like to thank those members of the Network Interoperability Consultative
Committee (<eref target="http://www.nicc.org.uk/"/>) and in particular to Clive Feather, who
contributed to the NICC specification for a Central Number Portability Database from which
this work is derived. </t>
<t>The author would also like to thank Alexander Mayrhofer for his assistance.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.5234" ?>
<?rfc include="reference.RFC.3986" ?>
<?rfc include="reference.RFC.2119" ?>
<?rfc include="reference.I-D.ietf-enum-cnam" ?>
<?rfc include="reference.I-D.ietf-enum-3761bis" ?>
</references>
<references title="Informative References">
<?rfc include="reference.RFC.1035" ?>
<?rfc include="reference.RFC.4395" ?>
<?rfc include="reference.I-D.ietf-enum-enumservices-guide" ?>
<reference anchor="E.164">
<front>
<title abbrev="E.164 (02/05)">The international public telecommunication numbering plan</title>
<author initials="" surname="" fullname="">
<organization abbrev="ITU-T">ITU-T</organization>
</author>
<date month="Feb" year="2005"/>
</front>
<seriesInfo name="Recommendation" value="E.164 (02/05)"/>
</reference>
</references>
</back>
</rfc>
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