Global ENUM Implementation

1
Global ENUM Implementation

• DTI ENUM Workshop5 June 2001
• London, UK

Robert Shaw ltrobert.shaw_at_itu.intgt ITU Internet
Strategy and Policy Advisor International
Telecommunication Union
2
Caveats

• Complex topic
• Focused on E.164 policy and infrastructure issues
• ENUM services are primarily national issues
• with some exceptions (e.g., 800)
• Work in progress

3
What is E.164?

• ITU-T Recommendation E.164 The international
  public telecommunication numbering plan
• Tied to treaty obligations (specific roles and
  obligations defined for ITU Member States and TSB
  Director)
• Defines number structure and functionality for
  four principal categories of numbers
• Geographic Areas
• Global Services
• Networks
• Groups of Countries (GoCs)

4
Examples of E.164 Resources

• Geographic areas
• ITU Member States, including integrated numbering
  plan involving more than one (e.g., 1)
• Global Services
• e.g., Universal International 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

5
Related to E.164

• ITU-T Recommendation E.164.1 Criteria and
  procedures for the reservation, assignment and
  reclamation of E.164 country codes and associated
  Identification Codes (ICs)
• ITU-T Recommendation E.164.2 E.164 numbering
  resources for trials (to be published)
• Determined Recommendation E.164.3 Principles,
  criteria and procedures for the assignment and
  reclamation of E.164 country codes and associated
  identification codes for Groups of Countries
  (determined at January 2001 meeting of SG2)
• ITU-T Recommendation E.190 Principles and
  responsibilities for the management, assignment
  and reclamation of E-series international
  numbering resources
• E.195 ITU-T International numbering resource
  administration

6
Issues of Convergence

• Problems of addressing calls that pass from one
  network service to another
• Now widely possible to originate calls from IP
  address-based networks to other networks
• But uncommon to terminate calls from other
  networks to IP address-based networks
• To access a subscriber on an IP address-based
  network, some sort of global addressing scheme
  across PSTN and IP address-based networks needed
• ENUM may be the glue solution

7
What is ENUM?

• IETF protocol defined in RFC 2916
• E.164 number used to look up Uniform Resource
  Identifier (URI)
• Web addresses most commonly known URI
• Allows using E.164 number in context of combined
  PSTN IP services (email, fax, SIP address,
  coordinates, IP telephony routing, other?)
• Could be important integrator of PSTN, Internet,
  and other IP-based networks

8
What is ENUM?

• Protocol uses what are called Naming Authority
  Pointer (NAPTR) DNS resource records as defined
  in RFC 2915
• Identifies the available methods or services for
  contacting a specific Internet node identified
  through an E.164 number as well as their order of
  priority/preference
• e.g., redirect calls, follow-me services,
  contact by email, look up public key, ???

9
How would E.164 numbers be mapped into the DNS?

• Reverse map digits in an E.164 number into
  separate DNS names
• Concatenate with ENUM root zone (e.g., foo.tld)
• For example
• 33 1 40 20 51 51 1.5.1.5.0.2.0.4.1.3.3.foo.tld
  
• What foo.tld is and how exactly it is
  administrated is under discussion

10
Roles and Responsibilities

• In telecommunication numbering, regulatory
  tradition with strong government involvement
  (e.g., number portability, anti-slamming)
• In the Internet, management of naming and
  addressing has been left to industry
  self-regulation
• Among early movers, assumption appears to be that
  national numbering/regulatory authorities will be
  involved in assisting in ENUM deployment for
  their portion of E.164 resources in respective
  countries

11
Roles and Responsibilities

• Most ENUM service and administrative decisions
  are national issues under purview of ITU Member
  States, since most E.164 resources are utilized
  nationally
• ITU to ensure that Member States have
  specifically authorized inclusion of geographic
  country code in the DNS
• In integrated numbering plan, each ITU Member
  State within plan may administer their portion of
  E.164 resources mapped into DNS as they see fit

12
Basic Technical Requirements

• Scaleable, robust and secure DNS infrastructure
  must be provided at all hierarchical levels of
  the DNS.
• Hierarchical registry operations and name servers
  that coordinate delegations of E.164 numbering
  resources will need to be deployed at the
  international, national and sub-national levels
• Important for geopolitical, sovereignty, security
  and other pragmatic reasons

13
DNS Infrastructure

• To support geographically dispersed national
  resources, the ENUM root zone foo.tld require DNS
  backbone dispersed around the world
• Main ENUM name servers (e.g., root zone CC)
  should be capable of sustaining loads probably
  comparable to that carried by current root name
  servers
• Geopolitical and technical constraints need to be
  balanced (e.g., limitations of 15-20 name
  servers)

14
DNS Infrastructure

• Following principles of E.164, important to have
  country-neutral, internationally acceptable
  solution
• History of DNS suggests that transparency needed
  as to clear legal and policy framework, roles,
  responsibilities and relationships
• General view that desirable to have one public
  ENUM name space (one root)
• Global infrastructure choices needs to reviewed
  in this context (e164.arpa, .arpa name server
  deployment)

15
Current .arpa Name Server Deployment
16
ITU Responsibilities

• Operate a registry function or coordinate a
  registry function for top level of E.164
• Outsource or coordinate the outsourcing of ENUM
  name servers corresponding to top level of E.164
  numbering plan
• Define and implement administrative procedures
  that coordinate delegations of E.164 numbering
  resources into these name servers

17
Remaining Issues

• Requirement for review of E.164 legal and policy
  framework when reflected in DNS?
• Without safeguards, ITU Member States will find
  their E.164 resources are provisioned or shadowed
  in alternative name spaces outside of their
  control
• Like DNS country codes, could E.164 resources
  be marketed outside their intended
  geographic/regulatory framework (e.g., .tv, .md,
  .ws, .bz)?

18
Remaining Issues

• Privacy
• Hardening the ENUM zone data against data mining
  but hard to stop ENUM name servers being
  harvested for resources bound to an E.164 number
• Could drive non-DNS based ENUM solution (e.g.,
  LDAP-based)
• Financial operations issues
• Major ENUM name servers probably cost US
  150,000-500,000 per year to operate
• ITU Member States Sector Members need to
  consider how global infrastructure costs will be
  shared

19
ITU Current Activities

• Ongoing review of policy and technical issues
  with assistance of Nominum, Inc.
• Preparation of in-depth technical and policy
  requirements discussion paper
• ITU-T SG 2 preparing supplement on issues that
  need to be addressed by national and
  international authorities
• ITU-T SG 2 Meeting in Sept 2001
• Further discussion with IETF on roles and
  responsibilities
• Plan for testbed countries?

20
Thank You

• References and resources
• http//www.itu.int/infocom/enum/