ENUM Administration Issues Some numbering perspectives ITUT ENUM
ENUM Administration Issues Some numbering perspectives ITU-T ENUM Workshop Geneva 17 January 2001 Tony Holmes BT tony. ar. holmes@bt. com Steve Lind AT&T sdlind@att. com
Agenda • WP 1/2 Liaison to IETF/ISOC • Some typical call flows • ENUM DNS structure and Hierarchy • ENUM Considerations and issues A glossary of terms used can be found at the end of this slide pack
The Aim of this session • To help raise awareness and assist administrations in understanding what needs to happen to make ENUM work • To consider the administration requirements of ENUM • To identify issues …. . not only those that need to be tackled by the ITU but also by Member States and other parties
WP 1/2 Liaison to IETF/ISOC q Results of DNS Administrative discussions and Contributions - October 2000 ITU-T WP 1/2 Meeting - Berlin. q Understandings regarding the method for administering and maintaining the E. 164 -based resource data in the DNS. q Administration = provision and update of E. 164 numerical values, of domain “e 164. arpa”, in the DNS. q Example of “e 164. arpa” domain name: 1. 5. 0. 2. 0. 4. 1. 3. 3. e 164. arpa q Administrative Zones defined: e 164. arpa = Domain Zone 3. 3 = Country Code Zone 1. 5. 0. 2. 0. 4. 1 = National Zone Note: Here ‘Zone’ refers to a segment of the domain name
WP 1/2 Liaison to IETF/ISOC q Agreements regarding the administration of Zones v Domain Zone is outside the scope of the ITU v Country Code Zone • ITU provides assignment data to the DNS Administrator • ITU Member States authorize/deny the ITU to notify the registrar of E 164. arpa to include their Country Code • No data entry for “spare” or test codes v National Zone • National Matter - determined by each Member State • Shared Network Codes - each entity determines • Groups of Countries - the administrative entity for the Group determines, in consultation with participating Member States
WP 1/2 Liaison to IETF/ISOC • Other Agreements v Once data input is authorized, each Member State/Administrative Entity is responsible for update and accuracy of data. v Data not authorized for input will not be entered in the DNS. v All Administrative Entities (including the DNS Administrator) will adhere to the tenets of pertinent ITU Recommendations e. g. E. 190, E. 164 etc. v WP 1/2 will provide guidance to assist the Member States and Administrative Entities in the performance of their responsibilities - the purpose of this meeting.
Typical call flows PSTN - IP +41 22 730 5887 DNS 4 DNS look up returns NAPTR record with itu@sipservice. foo 7 SIP server routes call to user 6 DNS returns SIP server IP address IP Network +44 1473 123456 1 +41 22 730 5887 PSTN 5 Gateway looks up host for Gateway itu@sipservice. foo 2 +41 22 730 5887 3 ( ENUM functionality) formats url 7. 8. 8. 5. 0. 3. 7. 2. 2. 1. 4. e 164. arpa
Typical call flows IP - PSTN +41 22 730 5887 DNS 1 +44 1473 123456 2 Client formats url 4 3 DNS returns record as url tel: +441473123456 Location server SIP Client initiates INVITE to server using tel url 5 SIP sever looks up gateway address from LS +44 1473 123456 IP Network 6 LS returns IP address of Gateway 7 Call routed to Gateway IP address PSTN Gateway 8 Gateway completes call to PSTN
ENUM - DNS Structure & Hierarchy e 164. arpa RIPE NCC Tier 1 Registry Tier 2 Service Registrar Tier 3 Application Service Provider 4. 4. e 164. arpa 1. 6. e 164. arpa
ENUM Considerations - 1 Inserting numbers in the DNS Tier 1 Registry • Registries will be identified by each participating Member State • Entries will point to the Service Registrar for a number ITU & IETF position states: ITU has responsibility to provide assignment information. Geographic Country Codes will only be included in the DNS when authorised by the Member State responsible for that code ISSUE • An agreed process needs to be developed e. g. between appropriate authorities (participating Member States, potentially ITU-T) and Tier 1 Registries
ENUM Considerations - 2 Inserting numbers in the DNS Tier 1 Registry ITU & IETF position states: Each administration is responsible for ensuring DNS administrators (Registries) are aware of appropriate changes ISSUES • Maintaining integrity of E. 164 • Building ENUM integrity • Not all countries have the same regulation or rules of administration BUT all need to address the same issues for ENUM • How should Tier 1 Registries be selected? - it’s a national matter but there are options…….
ENUM Considerations - 3 Inserting numbers in the DNS Tier 1 Registry …could be one or more Tier 1 Registry providers per CC e. g. - integrated number plan could be separated by national authorities - Tier 1 Registry(s) could be separated by number ranges within a CC but there can only be one Registry per E. 164 number ISSUES • How to determine the most appropriate arrangement? • Who runs national Registries? • An agreed process needs to be developed between participating Member States and their Tier 1 Registry provider(s) (national matter).
ENUM Considerations - 4 Inserting numbers in the DNS Tier 1 Registry ITU & IETF position states: For national zone resources behind the CC shared by Networks the resource assignee is responsible for providing E. 164 assignment information to the DNS Administrator • Network Code assignees need to be made aware of ENUM rules • ITU Recs may require amendment to embrace this ITU & IETF position states: For national zone resources behind the CC shared by Groups of Countries the resource assignee is responsible for providing E. 164 assignment information to the DNS Administrator • ITU Recs may require amendment/development to embrace this
ENUM Considerations - 5 Inserting numbers in the DNS Tier 1 Registry e 164. arpa Tier 1 Registry Tier 2 Service Registrar Entries in the Tier 1 Registry point to the Service Registrar for an E 164 number ISSUE • In some cases with Number Portability, the name server must point to a Service Registrar on an individual E 164 number basis, not a number block • The full implications on all methods of NP and associated processes need to be understood
ENUM considerations - 6 Inserting numbers in the DNS Enables the use of an E. 164 number allocated to a Service Provider to be used to deliver calls to another Service Provider ISSUES • Network by-pass • Some countries are moving to single number administration and payment for numbers, does this raise additional issues? • Rights of ownership? - differences across administrations? - Intellectual Property Rights?
ENUM considerations - 7 Inserting numbers in the DNS Enables the use of an E. 164 number allocated to a Service Provider to be used to deliver calls to another Service Provider ISSUES • Customer perception where an E. 164 number that provides access to an ISP, other than the one responsible for the number, experiences differing Qo. S and cost? • Privacy of information/consumer protection • Legal intercept? • Regulatory implications e. g monitoring of Qo. S etc?
ENUM Considerations - 8 Inserting numbers in the DNS Tier 2 Service Registrar e 164. arpa Tier 1 Registry Tier 2 Service Registrar points to Registry points to Service Registrar for an E. 164 number hosts NAPTR records for E. 164 numbers All records for a given number must be in one name server ISSUE • Determination of who qualifies to be a Service Registrar? Two alternatives under discussion Model 1 - any accredited domain name/service registrar Model 2 - telephone service provider
Reference Model I (General) T 1 E Legend ASP Application Service Provider T 1 E Tier 1 Entity (Registry) T 2 E Tier 2 Entity (Registrar) TSP Telephony Service Provider EU End User New T 2 E A H ** End User can be the end user itself or an agent authorized to represent the end user. ** TSP can offer application services also. The “TSP” entity performs functions specific to the TSP. B C T 2 E EU F G D TSP E ASP
ENUM Considerations - 9 Reference Model I New T 2 E T 1 E Model I Pros & Cons A C H T 2 E EU B G F TSP D E ASP Pros: • EU determines T 2 E, EU has more control • EU can be T 2 E (e. g. , universities and enterprises) for his/her own E. 164 number(s) • Enable competitive T 2 E service offering Cons: • More complicated interactions among involved entities • More efforts at T 2 E to manage the NAPTR RRs
Reference Model II (T 2 E=TSP) T 1 E Legend ASP Application Service Provider T 1 E Tier 1 Entity T 2 E Tier 2 Entity TSP Telephony Service Provider EU End User A’ B’ T 2 E/TSP EU E’ C’ D’ New T 2 E/TSP ASP ** End User can be the end user itself or an agent authorized to represent the end user. ** TSP can offer application services also. The “TSP” entity performs functions specific to the TSP.
ENUM Considerations - 10 Reference Model II T 1 E A’ B’ T 2 E/TSP EU E’ D’ New T 2 E/TSP C’ ASP Pros: • Fewer interfaces to deal with • Easier to verify End Users’s identity and ownership of the E. 164 Number • More incentives for TSPs to get involved in ENUM process (e. g. , verify End User’s ownership of a E. 164 Number and inform T 1 E about E. 164 number service disconnect) Cons: • Only TSPs can be T 2 E, non-competitive if there is only one TSP in a serving market • Non-TSPs cannot be T 2 E • End Users cannot be T 2 E for their own E. 164 Numbers • End Users cannot get ENUM service if none of TSPs in the serving market offers ENUM service
ENUM Considerations - 11 Inserting numbers in the DNS Tier 2 Service Registrar Some Administration issues from the Service Registrar models • Is one, or a number of different model(s) preferable? • Who should be Service Registrars? • How can E. 164/DNS integrity be safeguarded if responsibility for number insertion in the DNS lies with the customer? • How should validation of subscriber identity, data & NAPTR (service records) occur? • How can number/name hijacking/fraud be prevented?
ENUM Considerations - 12 Inserting numbers in the DNS ISSUES • How will number changes/number churn be handled? • How will ceased numbers be notified/recovered? • Could prepaid mobile numbers be inserted? • If so how will ownership be validated ? • How will changes/ownership/loss/ theft/cease issues be addressed? • Who has these responsibilities?
ENUM Considerations - 13 Inserting numbers in the DNS ISSUES • Geographic numbers would lose location information, will begin to look more like personal numbers • Impact on number plans/number administration? • Are additional controls required where numbers are shared? • Should/could requirements on carriers/third parties be enforced? • Do ENUM procedures and rules apply if E. 164 numbers are inserted in other domain name space (e. g. com/other domains) ?
- Slides: 25