ENUM. Patrik FältstrF. ltström Consulting Engineer, Office of the CSO Area Director, Applications Area, IETF cisco.

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1 ENUM Patrik FältstrF ltström Consulting Engineer, Office of the CSO Area Director, Applications Area, IETF cisco.com 1

2 Agenda Background Problem we want to solve Technical solution Conclusion 2

3 Background 3

4 The Domain Name System It is a distributed database It is a protocol Often the two get mixed up 4

5 DNS as distributed database Server for com Central server, root server Local resolver Server for se Client Server for jp 5

6 Recursion Root-server Query a.paf.se? Query a.paf.se? Local resolver Query a.paf.se? Ask se! Ask paf.se! Query a.paf.se? Server se Server paf.se 6

7 Domains and zones "root" se c zone "a.se." a ns domain "a.se." b ns domain/zone "b.a.se." ns 7

8 E.164 numbers Handled by the ITU, SG2/WP1/2 Agreements between member states of ITU how E.164 numbers are to be used, and allocated Hierarchically allocated 8

9 Structure of E.164 Structure to use for geographic areas CC 1-3 digits NDC N digits SN Max (15-N) digits National (significant) number International public telecommunication Number for geographical areas 9

10 Problem we want to solve 10

11 Problem 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 enable new services while enabling competition, consumer choice and consumer protection? 11

12 Problem statements 2(2) How can consumers and carriers have equal access to these new opportunities? How do you make this simple and easy to use without reinventing the wheel? 12

13 Technical solution 13

14 Solution in short Put telephone numbers in the global domain name system, DNS ENUM Working Group in the DNS created to solve the problem Domainname in URI out [mailto, sip, tel, http or other URI scheme] Solution was to use NAPTR records 14

15 Why DNS? It s there It works It s global It scales It s fast It s open Grandfather existing DNS delegation mechanisms, which looks like delegation in E.164 world ENUM enabled DNS provides a low cost, shared SCP like infrastructure for IP infrastructure ENUM is PSTN/IP convergence 15

16 Step 1 Take an E.164 number and create a fully qualified domain name in a single highly defined and structured domain e164.arpa. 16

17 Step 1 Explanation Each digit becomes 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 nameservers for NAPTR/service resource records (RR s) 17

18 Step 2 Lookup NAPTR RR s in DNS, and apply NAPTR/ENUM algorithm 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 ( ) 18

19 Step 2 in detail $ORIGIN e164.arpa. IN NAPTR U mailto+e2u!^.*$!mailto:spam@paf.se! IN NAPTR U ldap+e2u!^+46(.*)$!ldap://ldap.telco.se/cn=0\1 Note that no line break should be in the records 19

20 ENUM DNS Hierarchy Alternative 12 e164.arpa 6.4.e164.arpa 1.e164.arpa 18 different countries i.e. a real political problem e164.arpa e164.arpa 20

21 ENUM Hierarchy Two-tier model CC delegate according to primary delegation in E.164 space Secondary delegation is done by telco One tier model CC delegate according to secondary delegation In both of the cases, delegation can be done on the full DNS name for the E

22 Conclusion 22

23 ENUM example flow/usage Query e164.arpa? Response DNS-Server Call setup Dial Sip Sip proxy Sip proxy 23

24 ENUM and VoIP ENUM allows VoIP proxies and servers to find each other Intra and inter domain call setup Only for declaring ability to accept certain applications ENUM is an opt-in system (also on country code level) 24

25 ENUM in Universal Messaging IETF Voice Profile for Internet Mail ENUM enables carrier and enterprise voice mail systems to find each other, interoperate and exchange messages Linkage to directory gives access to spoken name as well as authenticated access to sensitive information (privacy) 25

26 ENUM in Internet Fax IETF RFC 2305 / ITU T-37 ENUM enables internet aware fax machines to find each other, interoperate and exchange messages 26

27 What ENUM is not Carrier selection (selection of carrier given a specific service type) Telco bypass Number portability Changing the E.164 numbering plan ENUM respects rights and prerogatives of nation states 27

28 Status as of Oct 24, 2000 (done) Base spec published as RFC 2916 e164.arpa delegated to RIPE-NCC ITU/IETF MOU agree on global delegation issues ITU SG2/WP1/2 made decisions Member state can inform ITU on who runs DNS 28

29 Status as of Oct 24, 2000 (not done) Who manages DNS servers for CC Short term / testing Long term / operational National issues Collecting and validating data for subscribers Distribution of data to servers Integration with existing E.164 numbers Consistency with portability Prevent Number Slamming and Hijacking 29

30 Resources RFC ENUM WG charter My address 30

31 Presentation_ID 31

ENUM. Overview July 2003

ENUM. Overview July 2003 ENUM Overview July 2003 The ENUM Objective Mapping PSTN addresses into the IP world ENUM allow any IP device to establish whether an E.164 telephone address is described by an Internet Service Point address