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ENUM Tutorial

ENUM Tutorial. ENUM Forum June 3, 2003 Steven D. Lind, AT&T GEN0075R0. Disclaimer. Heavily borrowed from: Patrik Faltstr öm’s IETF presentation to February 2002 ITU Workshop on ENUM AT&T/ENUM Forum presentation to December 2002 SG2 meeting Added some telecomm perspective. Assumption.

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ENUM Tutorial

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  1. ENUM Tutorial ENUM Forum June 3, 2003 Steven D. Lind, AT&T GEN0075R0

  2. Disclaimer • Heavily borrowed from: • Patrik Faltström’s IETF presentation to February 2002 ITU Workshop on ENUM • AT&T/ENUM Forum presentation to December 2002 SG2 meeting • Added some telecomm perspective

  3. Assumption • Use of standard telephone numbers is not going away • PSTN/analog terminals are going to be around • IP phones use 12-button keypad • Globally unique identifier that has established familiarity with end users

  4. Problem statements • How do network elements (gateways, SIP servers etc) find services on the Internet if you only have a telephone (E.164) number? • How can subscribers define their preferences for incoming communications?

  5. More Problem Statements • How do you address an IP-based voice terminal from the PSTN? • For a call that starts out as VoIP, how do you know to keep the call on the IP-plane (as opposed to the PSTN) for a dialed telephone number if the customer is not yours?

  6. Today, Many Addresses tel:+46-8-971234 mailto:paf@example.com tel:+46-706051234 sip:paf@example.com

  7. With ENUM, Only One tel:+46-8-971234 mailto:paf@example.com ENUM tel:+46-706051234 tel:+46-706051234 sip:paf@example.com Give this number to friends: +46-8-971234

  8. Solution in short • Put domain names derived from telephone numbers in the global domain name system, DNS • IETF ENUM Working Group created to solve the problem of using the DNS for: • domain name in • [Numbers re-formatted as domain names] • URI out • [mailto, sip, tel, http or other URI scheme] • Solution: NAPTR records • Use the URI’s for the communication

  9. ENUM in a nutshell • take phone number +46-8-6859131 • turn into domain name 1.3.1.9.5.8.6.8.6.4.e164.arpa. • ask the DNS mailto:paf@cisco.com • return list of URI’s sip:paf@cisco.com

  10. The input to the NAPTR algorithm Step 1 • Take an E.164 number and create a fully qualified domain name in a single highly defined and structured domain • +46-8-971234 • +468971234 • 4.3.2.1.7.9.8.6.4.e164.arpa.

  11. Step 1 - Explanation • Each digit can become a definable and distributed “zone” in DNS terms • Delegation can (doesn’t have to) happen at every digit, including at last digit • Zones such as country codes, area codes or primary delegated blocks of numbers can be delegated as well as individual numbers • DNS defines authoritative name servers for NAPTR/service resource records

  12. Step 2 • Lookup NAPTR RR’s in DNS, and apply NAPTR/ENUM algorithm 4.3.2.1.7.9.8.6.4.e164.arpa. !^.*$!mailto:spam@paf.se! !^+46(.*)$!ldap://ldap.telco.se/cn=0\1! • Use rewrite rules using regular expressions which operate on the E.164 number (+468971234)

  13. Regular Expressions • For ENUM, the NAPTR regexp field may yield an (unchanged) URL • !<regexp>!<string>! • “Match <regexp> on original E.164, and apply rewrite rule <string>” ^ - Match beginning $ - Match end . - Match any character .* - Match any number of any character () - Grouping, \n in <string> is replaced with group number ‘n’ in <regexp>

  14. Step 2 in detail • $ORIGIN 4.3.2.1.7.9.8.6.4.e164.arpa. • IN NAPTR 10 10 ”U” ”mailto+E2U” ”!^.*$!mailto:spam@paf.se!” • IN NAPTR 20 10 ”U” ”ldap+E2U” ”!^+46(.*)$!ldap://ldap.telco.se/cn=0\1” • Note that no line break should be in the records

  15. ENUMEnabledApplications Provisioning DomainNameSystem Authentication &ValidationEntities Tier 0 Registrar Registry Tier 1 • voice • fax • messaging & presence • email • web pages ApplicationServiceProvider Tier 2

  16. sweden_enum.com (4.4.e164.arpa) nsnanp.enum.com (3.7.9.1.e164.arpa) e164.att.net The Public ENUM Infrastructure e164.arpa Tier 0 (Country Code Registry) $ORIGIN e164.arpa. 3.7.9.1 IN NS nsnanp.enum.com . 4.4 IN NS sweden_enum.com . … … Tier 1 (Telephone Number Registry) $ORIGIN 3.7.9.1.e164.arpa. 7.9.7.6.6.3.2 IN NS e164.att.net . 8.9.7.6.6.3.2 IN NS e164.xyz.com . … Tier 2 (Application Information) $ORIGIN 7.9.7.6.6.3.2.3.7.9.1.e164.arpa. IN NAPTR 100 10 "u" "sip+E2U" "!^.*$!sip:19732366797@att.net!" . International Implementation worked in IETF and ITU-T National Implementation worked in ENUM Forum (US)

  17. Delegation of Country Codein Tier 0 • Draft Recommendation E.A-ENUM in progress • Interim Procedures in place between IAB/ISOC and ITU-TSB • Use of e164.arpa pending outcome of Recommendation • Requests must be authenticated by TSB before RIPE-NCC can act • Country Code must be valid and assigned • Position of National Numbering Administrator must be known and must opt-in • Similar situation for shared Network codes and codes for Groups of Countries (e.g., ETNS)

  18. Country Code Delegationsas of 23 May 2003

  19. National Implementation in the US • ENUM Forum organized in August 2001 to address technical specifications • “ENUM Forum Specifications for US Implementation of ENUM” (6000_1_0) approved and reviewed with USG in February, 2003 • Requirements for Tier 1 Registry • Specifications and guidelines for Registrar & Tier 2 nameserver • Need mechanism for contracting with Tier 1 operators

  20. Requirements Document • Reference Architecture • Tier 1 Registry Operations, Security, & Admin • Tier 1 Performance Specifications • Privacy Considerations • Provisioning • Registrar Requirements • Authentication & Authorization • Tier 2 Requirements & Guidelines • Conflict Resolution • Issues Out of Scope

  21. Root Tier 0 Tier 1 Registry Registrant Registrar Tier 2 Provider Reference Architecture

  22. Reference Architecture • Registrar • Registrant • Tier 1 Registry • Does not address non geographic numbers • Tier 2 Service Provider • Tier 2 contains the NAPTR records or delegations • Interfaces • Issue: • One or More Tier 1 Providers • Delegation at Tier 0 by NPA

  23. Tier 1 Aspects • Tier 1 Operations • Zone Information (aka zone files) • ContactInfo (aka WhoIs) • Reporting, backup, escrow & performance requirements • Performance Aspects • DNS Performance • EPP Interfaces • Tier 1 Security • Administrative Aspects • Dispute Resolution • Data Collection and Privacy

  24. Privacy Considerations • Registrant Choice • Privacy Analysis • Open Disclosure of Registrant Information in DNS • Information Handling During Registration and Provisioning • Contact Info • Fair Information Practices

  25. Provisioning Authentication & Validation Entities Tier 1 Registry Registrant Registrar Tier 2 Nameserver Application Service Provider

  26. Provisioning Aspects • Registrar Requirements • Registrant Validation & Authentication • Dispute Resolution • Registrar Infrastructure Requirements • Recommended Practices & Requirements • Various Scenarios • Information Flows • Tier 2 • Mostly Guidelines – Some Requirements • Tier 2 may be self-provided or from a commercial 3rd party • Interfaces & Interactions • Performance Recommendations

  27. DNS-Server Examples SIP-Server SIP-Server Internet PSTN Gateway Gateway Calling party Called party

  28. DNS-Server Gateway Sip server PSTN to VoIP Call via SIP Query 1.3.1.9.5.8.6.8.6.4.e164.arpa.? Response sip:paf@cisco.com “Call setup” Dial +4686859131 Sip sip:paf@cisco.com

  29. DNS-Server VoIP via SIP to VoIP SIP-Server “ENUM” SIP-Server Gateway Gateway

  30. DNS-Server VoIP via PSTN to PSTN SIP-Server “ENUM” SIP-Server Gateway Gateway

  31. Future Actions • Address implementation issues • Contracting model • Integration/separation of North American countries • Number of Tier 1 operators • Address Non-geographic numbers (specifically 8YY Toll Free) • Can’t be cleanly separated by North American country • Has unique provisioning requirements

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