International Telecommunication Union
Global ENUM Implementation
DTI ENUM Workshop
5 June 2001
London, UK
Robert Shaw
<robert.shaw@itu.int>
ITU Internet Strategy and Policy Advisor
International Telecommunication Union
International Telecommunication Union
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
International Telecommunication Union
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”)
International Telecommunication Union
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
International Telecommunication Union
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
International Telecommunication Union
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…
International Telecommunication Union
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
International Telecommunication Union
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, ???
International Telecommunication Union
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
International Telecommunication Union
Roles and Responsibilities
• In telecommunication numbering,
regulatory tradition with strong government
involvement (e.g., number portability, antislamming)
• In the Internet, management of naming and
addressing has been left to “industry selfregulation”
• 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
International Telecommunication Union
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
International Telecommunication Union
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
International Telecommunication Union
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)
International Telecommunication Union
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)
International Telecommunication Union
Current .arpa Name Server Deployment
i.root-servers.net
NORDUNET/KTH
Stockholm, Sweden
d.root-servers.net
University of Maryland
College Park, MA, USA
e.root-servers.net
NASA (Ames)
Mt. View, CA, USA
f.root-servers.net
ISC
Palo Alto, CA, USA
b.root-servers.net
USC-ISI
Los Angeles, CA, USA
c.root-servers.net
PSINet
Ashburn, VA, USA
h.root-servers.net
US Department of Defense (ARL)
Aberdeen, MA, USA
g.root-servers.net
US Department of Defense (DISA)
Vienna, VA, USA
a.root-servers.net
Verisign GRS
Herndon, VA, USA
International Telecommunication Union
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
International Telecommunication Union
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)?
International Telecommunication Union
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
International Telecommunication Union
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?
International Telecommunication Union
Thank You
• References and resources
– http://www.itu.int/infocom/enum/