ENUM

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ENUM

• 2006. 5. 16
• ???
• icebyung_at_hufs.ac.kr

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ENUM ????

• ??? ???? ??, ?? ? ???? ???? ??? ???

tel[phone]
mailtopaf_at_example.com
tel[phone]
With ENUM (E.164 Number Mapping)
tel[phone]
Need only one number tel[phone]
mailtopaf_at_example.com
ENUM
tel[phone]
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E.164

• ITU-T Recommendation E.164 The international
  public telecommunication numbering plan
• Linked to treaty obligations (specific roles and
  obligations defined for ITU Member States and TSB
  Director)
• Defines number structure and functionality for
  three principal categories of numbers
• Geographic Areas (including country codes)
• Global Services
• Networks
• Types of E.164
• Geographic areas
• ITU Member States, including integrated numbering
  plan involving more than one (e.g., 1)
• Global Services
• e.g., UIFN Freephone Numbers (800)
• Networks
• Global Mobile Systems (881 1 digit IC)
• Shared code for Networks ( 882 2 digit IC)
• Groups of Countries
• e.g., ETNS

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ENUM Overview
ENUM
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ENUM Overview (User ENUM)

• Look up what services are available for an E.164
  number (or private dialing plan) in a
  decentralized way with distributed management of
  the different levels in the lookup process
  through
• Transformation of E.164 numbers into domain name
• Use of existing DNS service

Transformation
DNS Lookup
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ENUM Overview (Carrier/Infrastructure ENUM)

• ???? ?? ??? DNS ? ??, ?? ??? ?? ??? ?? ???? ????
  ??
• ??? ?? ???? ?? ?? ??

ENUM DNS
ITSP 070 123 abc.co.kr
ITSP 070 - 456 def.co.kr
Root
.e164.arpa
.2.8
4.3.2.1.4.5.6.0.7.0
call 070-456-1234
SSW ( Soft switch) ?? ???? ??
OSP (Open Settlement Protocol) ?? ???? ??
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DNS for ENUM

• ENUM ???? DNS ? ???? ?? 0 , 1 , 2 ? ??

• e164.arpa? ?? ??? Zone
• ? ??? ?? ??? ??

• E.164 ??? ?? ???? ????
• E.164 ??? ?? ??? ??
• ??? ?? ??
• Tier 1 Registry? ???? ???? Tier 0 e164.arpa?
  ??
• ? ??? ??

• ???? ??? ??? NAPTR ???? ??? ??
• Tier 1 Registry? Tier 2 ENUM DNS Provider?
  ???? ??

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DNS for ENUM

• ?? 1, 2 ?? ?? ?? ??
• Tier 1 ? ???? FQDN? ??
• ?? ??, ?? ??, ?? ??
• DNS Query ? ?? ??? ??? ??
• ?? ?? ?? ?? ??, ?? ? DNS ? ??? ???? ????? ??.
• ENUM ?? ?? ? DNS ? ???? ??
• Tier 1 ?? ??
• 2.8.e164.arpa ???? ?Upper layer
• ?? ?????? ?? ?? ? Sub layer
• Tier 2 ?? ??
• ENUM ?? ??

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NAPTR RR and ENUM

• DNS Message Format
• DNS Resource Records
• The data associated with domain names are
  contained in resource records, or RRs.
• ? RR ? ???? ??? ?? ??
• ? Type? ?? RR
• SOA Record (Start Of Authority) ?? ???? ?? ?????
  ??(authoritative)? ??? ?? ??? ??
• NS(Name Server) Record ?? ???? ?? delegation??
  ????? ??
• A Record ???? IPv4 ??? mapping
• AAAA Record ???? IPv6 ??? mapping
• CNAME Record ???? ?? ? ?? ?? ??
• MX(Mail eXchanger) Record ?? ???? ?? ??? ??? ??
• PTR(Pointer) Record IP ??? domain name?? reverse
  mapping? ??, Reverse Zone ???? ?

• Question question for the name server
• Answer RRs answering the question
• Authority RRs pointing toward an authority
• Additional RRs holding additional information

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NAPTR RR and ENUM

• NAPTR Resource Record
• A DNS RR which specifies a regular expression
  based rewrite rule that will produce a new domain
  label or Uniform Resource Identifier (URI).
• the resulting domain label or URI may be used
• in subsequent queries for the Naming Authority
  Pointer(NAPTR) resource records (to delegate the
  name lookup)
• or as the output of the entire process for which
  this system is used
• This allows the DNS to be used to lookup services
  for a wide variety of resource names (including
  URIs) which are not in domain name syntax.
• Main Applications
• URI resolution
• ENUM

DNS RR Format
NAPTR RR Format
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NAPTR RR and ENUM

• NAPTR RR Format
• Order the order in which the NAPTR records MUST
  be processed in order to accurately represent the
  order list of Rules
• The ordering is from lowest to highest
• Should be selected based on the combination of
  the Preference values and Services offered, if
  two records have same order values
• Preference the order in which NAPTR records with
  equal Order values SHOULD be processed
• A client MAY look at records with higher
  Preference values if it has a good reason to do
  so such as not supporting some protocol or
  service very well
• Flags controls whether the rewriting rule is
  terminated or not (empty flags)
• Application-specific single character (e.g, u
  in ENUM)
• Services specifies the Service Parameters
  applicable to this delegation path
• Up to the Application Specification to specify
  the value (e.g. tel, sip, mailto)

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NAPTR RR and ENUM

• NAPTR RR Format
• Regexp a substitute expression that is applied
  to the original string held by the client on
  order to construct the next domain name lookup
• Replacement a ltdomain-namegt which is the next
  domain-name to query for depending on the
  potential values found in the flags field
• Use when the regular expression is a simple
  replacement operation

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Communication between DNS and ENUM Client

• ???? IDDD? ??? ??? ??? E.164 ??? ??
• Ex 82-2-2186-4551
• ?? ?? (, - ? ?? ??? ??)
• Ex 82221864551
• ?(.)?? ?? ??
• Ex 8.2.2.2.1.8.6.4.5.5.1
• ??? ??? ??
• Ex 1.5.5.4.6.8.1.2.2.2.8
• ??? ??? ?? ???? ????? ??
• Ex 1.5.5.4.6.8.1.2.2.2.8.e164.arpa

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ENUM Query Message
header section
question section
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DDDS algorithm

• The DDDS algorithm is based on the concept of
  Rewrite Rules.
• These rules are collected into a DDDS Rule
  Database, and accessed by given unique keys.
• A given Rule, when applied to an Application
  Unique String, transforms that String into new
  Key that can be used to retrieve a new Rule from
  the Rule Database.
• This new rule is then re-applied to the original
  AUS and the cycle repeats itself until a
  terminating condition is reached.
• All Rewrite Rules for all Applications must
  ALWAYS apply to the exact same AUS that the
  algorithm started with.
• An Application MUST NOT apply a Rule to the
  output of a previous Rule.

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DDDS algorithm

• DDDS Algorithm

• AUS (Application Unique String)
• DDDS algorithm? ???? ???? key
• ENUM??? AUS? ??? ??? ?? ??? ? fully qualified
  E.164 ??

• FWKR (First Well-known Rule)
• AUS? ???? DDDS ??????? ???? key? ??? ??
• ENUM? ??, FWKR? ??? ???? ??

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Infrastructure ENUM

• e164??? ??? CSP (Communication Service
  Providers)? ??? peer ?? ? ?? ?? CSP?? ???? ?? ??
• CSP ?? ?? ???? ? ??? ?? ??? ???? ENUM ??? ??? ??
• User ENUM? Infrastructure ENUM? ????? ???? ??

Infrastructure ENUM? User ENUM ??
?? ?? Infrastructure ENUM User ENUM
?? ?? CSP ??, ENUM ???
?? ??? CSP only ??? ??
?? ??? CSPs ENUM ???
?? ??? ??? ????? CSP ENUM Registrar
?? ?? ?? All E.164??? ??(no opt-in) ??? ? opt-in
?? ??? CSPs only Any
?? ?? ?? Yes No
??? ?? No yes
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Types of Infrastructure ENUM

• CSP-Internal Infrastructure ENUM
• CSP Intranet??? ?? ??
• ?????? ??? ?? ???? ?? ???? ?? ??
• ?? CSPs, Public Internet, ?????? PSTN? ?? GW ??
  ??? ?? border elements? ?? ??
• ?????? CSP? ENUM ??? ???? ?? DB? ???? ??
• ??? DNS ???? ???? private ?? ??? public DNS? ??

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Types of Infrastructure ENUM

• CSP-Shared Infrastructure ENUM
• ??? ??? ??? ?? CSP? DNS data? ???? public DNS?
  ??? ? ??? ???? ?? ?? ?? ??? ??
• CSP? ?? CSPs?? border elements ??? ?? ??
• end-user? ?? CSP? end-user? ?? ???? ???? ??

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Types of Infrastructure ENUM

• Global (Common) Infrastructure ENUM
• ??? CSP?? ??? ? ? ?? ?? e164??? ??? ??? common
  ??? ??