International Telecommunication Union Global ENUM Implementation Robert Shaw ITU Internet Strategy...

International Telecommunication Union

Global ENUM Implementation

Robert Shaw

<[email protected]>

ITU Internet Strategy and Policy Advisor


DTI ENUM Workshop5 June 2001London, UK


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


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”)


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


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


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…


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


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, ???


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


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


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


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


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)


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)


Current .arpa Name Server Deployment

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

i.root-servers.net NORDUNET/KTH Stockholm, Sweden

d.root-servers.net University of Maryland College Park, MA, USA

g.root-servers.net US Department of Defense (DISA) Vienna, VA, USA

a.root-servers.net Verisign GRS Herndon, VA, USA

h.root-servers.net US Department of Defense (ARL) Aberdeen, MA, USA

c.root-servers.net PSINet Ashburn, VA, USA


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


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)?


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


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?


Thank You

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

International Telecommunication Union Global ENUM Implementation Robert Shaw ITU Internet Strategy...

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