7Domains and zones "root" se a c b ns ns ns zone "a.se." domain "a.se." domain/zone "b.a.se."bnsnsns
8Delegations Root server ns.nic-se.se se. IN NS ns.nic-se.se ns.nic-se.se. IN Ans.nic-se.sens.se. IN NS ns.nic-se.se.a.se. IN NS ns.a.se.c.se. IN NS ns.c.se.ns.nic-se.se. IN Ans.a.se. IN Ans.c.se. IN Ans.a.sea.se. IN NS ns.c.se.b.a.se. IN NS ns.b.se.ns.a.se. IN Ans.b.se. IN Ans.c.se.c.se. IN NS ns.c.se.ns.c.se. IN Ans.b.a.se.b.a.se. IN N S ns.b.a.se.ns.b.a.se. IN A
9E.164 numbersAllocation at CC level by the ITU, SG2/WP1/2 (from an IETF perspective)E.164 provides the number structure and functionality of numbers used for international publictelecommunicationsHierarchically allocated
10Structure of E.164 Structure to use for geographic areas CC NDC SN 1-3 digitsN digitsMax (15-N) digitsNational (significant) numberInternational public telecommunicationNumber for geographical areas
12Problem statements 1(2)How do network elements find services on the Internet if you only have a telephone (E.164) number?How can subscribers (as opposed to carriers) define their preferences for incoming communications?How can we (IETF/ITU) enable new services while enabling competition, consumer choice and consumer protection?
13Problem statements 2(2)How can consumers, carriers and new players have equal access to these new opportunities?How do we (IETF/ITU) make this simple and easy to use without reinventing the wheel?
15Solution in shortPut telephone numbers* in the global domain name system, DNSENUM Working Group created to solve the problem of using the DNS for:Domainname in[Numbers reformatted as domain names]URI out[mailto, sip, tel, http or other URI scheme]Solution was to use NAPTR records* Maybe not in the original E.164 format
16Example$ORIGIN e164.arpa. IN NAPTR "U" "sip+E2U" IN NAPTR "U" "ldap+E2U"
17Why DNS?It’s thereIt works… It’s global… It scales… It’s fast… It’s open…Grandfather existing DNS delegation mechanisms, which looks like delegation in E.164 worldENUM enabled DNS provides a low cost, shared SCP-like infrastructure for IP infrastructureENUM facilitates PSTN/IP convergence
18Step 1Take an E.164 number and create a fully qualified domain name in a single highly defined and structured domaine164.arpa.The input to theNAPTR algorithm
19Step 1 ExplanationEach digit becomes a definable and distributed “zone” in DNS termsDelegation can (doesn’t have to) happen at every digit, including at last digitZones such as country codes, area codes or primary delegated blocks of numbers can be delegated as well as individual numbersDNS defines authoritative nameservers for NAPTR/service resource records (RR’s)
20Step 2 Lookup NAPTR RR’s in DNS, and apply NAPTR/ENUM algorithm e164.arpa.!^+46(.*)$!ldap://ldap.telco.se/cn=0\1!Use rewrite rules using regular expressions which operate on the E.164 number ( )
21Regular expressionsFor 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>
22Step 2 in detail $ORIGIN 18.104.22.168.22.214.171.124.4.e164.arpa. IN NAPTR “U” “mailto+E2U”IN NAPTR “U” “ldap+E2U” “!^+46(.*)$!ldap://ldap.telco.se/cn=0\1”Note that no line break should be in the records
23ENUM DNS Hierarchy Alternative 2 Alternative 1 e164.arpa 6.4.e164.arpa
24+46-8-976123 ns.ripe.net e164.arpa. IN NS ns.ripe.net. 6.4.e164.arpa. IN NS ns.e164.se.ns.ns.e164.se. IN ARoot servere164.arpa. IN NS. ns.ripe.netns.ripe.net. IN Ans.e164.se6.4.e164.arpa IN NS ns.e164.se.e164.se. IN NS e164.telco.se.e164.telia.se. IN Ae164.telco.se.e164.se. IN NS e164.telco.se.e164.arpa. IN NS ns.eservice.net.ns.eservice.net.e164.arpa. IN NS eservice.net.e164.arpa. IN NAPTR …….
25DNS Hierarchy Strictly delegated One authoritative server for each name, and only oneHave led to the registry/registrar modelOne responsible registry, but many registrars which talk with customers
26Verisign Global Registry Registry/registrarRoot serverServer for .comVerisign Global RegistryRegistrars for .comToday 77Registrar for .comNetwork SolutionsActive ISPinterQ IncorporatedServer for .seNIC-SE ABRegistrar for .seTele2Registrars for .seToday 227
28ENUM example flow/usage DNS-ServerQuerye164.arpa?Response“Call setup”DialSipSip proxySip proxy
29ENUM and VoIP ENUM allows VoIP proxies and servers to find each other Intra and inter domain call setupOnly for declaring ability to accept certain applicationsENUM is an opt-in system (also on country code level)
30ENUM in Universal Messaging IETF Voice Profile for Internet MailENUM enables carrier and enterprise voice mail systems to find each other, interoperate and exchange messagesLinkage to directory gives access to “spoken name” as well as authenticated access to sensitive information (privacy)
31ENUM in Internet Fax IETF RFC 2305 / ITU-T Rec. T.37 ENUM enables internet aware fax machines to find each other, interoperate and exchange messages
32Detailed example of Fax Person X wants to send a fax to Person Y; she knows Y's E.164 number.Person Y has many IP applications tied to her own (Y's) E.164 number.Device C became responsible for delivering the fax. Device C is Internet Aware, is ENUM-enhanced, can do SMTP and SIP, but can't do H.323 yet.Device C does a DNS query on the E.164 number. Device C discovers from the response that Person Y prefers real-time to store-and-forward fax delivery, likes SIP and H.323 equally, and has SMTP, too.Device C tries SIP first. If SIP fails, Device C does not try H.323. Instead, Device C then tries SMTP.Note: Device C uses ENUM in its application selection logic. ENUM is an enabler and not the same sort of thing as SMTP, SIP, H.323, voice/fax/data, etc.
33From RFC 2916 4. IANA Considerations This memo requests that the IANA delegate the E164.ARPA domain following instructions to be provided by the IAB. Names within this zone are to be delegated to parties according to the ITU recommendation E.164. The names allocated should be hierarchic in accordance with ITU Recommendation E.164, and the codes should assigned in accordance with that Recommendation.Delegations in the zone e164.arpa (not delegations in delegated domains of e164.arpa) should be done after Expert Review, and the IESG will appoint a designated expert.
34Status as of Jan 10, 2001 (done) Base spec published as RFC 2916 e164.arpa delegated to RIPE-NCCITU SG2/WP1/2 liaison statement:Member state can inform ITU on entry of numbers in DNS, provision of E.164 information
35Status as of Jan 10, 2001 (not done) Delegation of domains below e164.arpa to managing entities that are appointed by member statesNational issues
36Resources NAPTR Resource Records (RFC 2915) ENUM Specification (RFC 2916)Liaison Statement (RFC 3026)IAB on need for unique root (RFC 2826)IAB Statement on ARPAMy address: