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ENUM Administration Issues. Some numbering perspectives. ITU-T ENUM Workshop Geneva 17 January 2001. Steve Lind AT&T [email protected] Tony Holmes BT [email protected] Agenda. WP1/2 Liaison to IETF/ISOC Some typical call flows ENUM DNS structure and Hierarchy

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Enum administration issues

ENUM Administration Issues

Some numbering perspectives

ITU-T ENUM Workshop

Geneva

17 January 2001

Steve Lind

AT&T

[email protected]

Tony Holmes

BT

[email protected]


Agenda

Agenda

  • WP1/2 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


Enum administration issues

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


Wp1 2 liaison to ietf isoc

WP1/2 Liaison to IETF/ISOC

  • Results of DNS Administrative discussions and Contributions - October 2000 ITU-T WP1/2 Meeting - Berlin.

  • Understandings regarding the method for administering and maintaining the E.164-based resource data in the DNS.

  • Administration = provision and update of E.164 numerical values, of domain “e164.arpa”, in the DNS.

  • Example of “e164.arpa” domain name:

    1.5.1.5.0.2.0.4.1.3.3.e164.arpa

  • Administrative Zones defined:

    e164.arpa=Domain Zone

    3.3=Country Code Zone

    1.5.1.5.0.2.0.4.1=National Zone

    Note: Here ‘Zone’ refers to a segment of the domain name


Wp1 2 liaison to ietf isoc1

WP1/2 Liaison to IETF/ISOC

  • Agreements regarding the administration of Zones

    • Domain Zone is outside the scope of the ITU

    • Country Code Zone

      • ITU provides assignment data to the DNS Administrator

      • ITU Member States authorize/deny the ITU to notify the registrar of E164.arpa to include their Country Code

      • No data entry for “spare” or test codes

    • National Zone

      • National Matter - determined by each Member State

      • Shared Network Codes - each entity determines

      • Groups of Countries - the administrative entityfor theGroup determines, in consultation with participating Member States


Wp1 2 liaison to ietf isoc2

WP1/2 Liaison to IETF/ISOC

  • Other Agreements

    • Once data input is authorized, each Member State/Administrative Entity is responsible for update and accuracy of data.

    • Data not authorized for input will not be entered in the DNS.

    • All Administrative Entities (including the DNS Administrator) will adhere to the tenets of pertinent ITU Recommendations e.g. E.190, E.164 etc.

    • WP1/2 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 look up returns

NAPTR record with

[email protected]

DNS

SIP server routes call to user

DNS returns SIP server IP address

IP

Network

6

2

1

5

4

7

3

+44 1473 123456

+41 22 730 5887

Gateway looks up host for

[email protected]

PSTN

Gateway

+41 22 730 5887

( ENUM functionality)

formats url

7.8.8.5.0.3.7.2.2.1.4.e164.arpa

Typical call flows PSTN - IP


Typical call flows ip pstn

DNS returns record as url

tel:+441473123456

+41 22 730 5887

DNS

+44 1473 123456

Client formats url

Location

server

SIP Client initiates

INVITE to server using tel url

IP

Network

LS returns IP address of Gateway

5

1

4

8

2

3

6

7

SIP sever looks up gateway address from LS

+44 1473 123456

Call routed to Gateway

IP address

PSTN

Gateway

Gateway completes call to PSTN

Typical call flows IP - PSTN


Enum dns structure hierarchy

ENUM - DNS Structure & Hierarchy

e164.arpa

RIPE NCC

Tier 1

Registry

4.4.e164.arpa

Tier 2

Service Registrar

1.6.e164.arpa

Tier 3

Application Service

Provider


Enum considerations 1

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

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

  • ISSUE

  • An agreed process needs to be developed e.g. between appropriate authorities (participating Member States, potentially ITU-T) and Tier 1 Registries


Enum administration issues

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 administration issues

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

  • - Tier1 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

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

ENUM Considerations - 4

  • Network Code assignees need to be made aware of ENUM rules

  • ITU Recs may require amendment to embrace this

  • ITU Recs may require amendment/development to embrace this


Enum administration issues

ENUM Considerations - 5

Inserting numbers in the DNS

Tier 1 Registry

e164.arpa

Tier 1 Registry

Tier 2 Service

Registrar

Entries in the Tier 1 Registry point to the Service Registrar for an E164 number

  • ISSUE

  • In some cases with Number Portability, the name server must point to a Service Registrar on an individual E164 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

ENUM considerations - 6

  • 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 administration issues

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 QoS and cost?

  • Privacy of information/consumer protection

  • Legal intercept?

  • Regulatory implications

    • e.g monitoring of QoS etc?


Enum administration issues

ENUM Considerations - 8

Inserting numbers in the DNS

Tier 2 Service Registrar

e164.arpa

Tier 1 Registry

points to Registry

Tier 2 Service

Registrar

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

Two alternatives under discussion

Model 1 - any accredited domain name/service registrar

Model 2 - telephone service provider

  • ISSUE

  • Determination of who qualifies to be a Service Registrar?


Enum administration issues

Reference Model I (General)

Legend

ASP Application Service Provider

T1E Tier 1 Entity (Registry)

T2E Tier 2 Entity (Registrar)

TSP Telephony Service Provider

EU End User

T1E

New T2E

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

T2E

E U

F

G

E

D

TSP

ASP


Enum administration issues

ENUM Considerations - 9

A

H

E U

TSP

Reference Model I

New T2E

T1E

Model I Pros & Cons

C

T2E

B

G

F

E

D

ASP

  • Pros:

  • EU determines T2E, EU has more control

  • EU can be T2E (e.g., universities and enterprises) for his/her own E.164 number(s)

  • Enable competitive T2E service offering

  • Cons:

  • More complicated interactions among involved entities

  • More efforts at T2E to manage the NAPTR RRs


Enum administration issues

Reference Model II (T2E=TSP)

T1E

Legend

ASP Application Service Provider

T1E Tier 1 Entity

T2E Tier 2 Entity

TSP Telephony Service Provider

EU End User

A’

B’

T2E/TSP

E U

** 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.

E’

C’

D’

ASP

New T2E/TSP


Enum administration issues

ENUM Considerations - 10

Reference Model II

  • 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 T1E about E.164 number service disconnect)

T1E

B’

A’

T2E/TSP

E U

E’

C’

D’

New T2E/TSP

ASP

  • Cons:

  • Only TSPs can be T2E, non-competitive if there is only one TSP in a serving market

  • Non-TSPs cannot be T2E

  • End Users cannot be T2E 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

ENUM Considerations - 11

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 administration issues

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 administration issues

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) ?


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