an ietf view of enum - icann · enum is not everything in particular, enum is not: • a directory...
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An IETF view of ENUMAn IETF view of ENUM
Geoff HustonGeoff HustonExecutive Director,Executive Director,
Internet Architecture BoardInternet Architecture Board
PresentedPresented at ICANN, Rio de at ICANN, Rio de JanieroJaniero, 2003, 2003byby Richard StastnyRichard Stastny
Who is the IETF?Who is the IETF?
Internet Engineering Task ForceInternet Engineering Task ForceThe organization that oversees the standards The organization that oversees the standards process for Internet protocols and technologiesprocess for Internet protocols and technologiesIndustryIndustry--based standards body with broad based standards body with broad participation from vendors, operators and participation from vendors, operators and researchersresearchersWe make standards that work We make standards that work –– how you work how you work them is up to you!them is up to you!
The Structure of the IETFThe Structure of the IETF
Huh? Huh? -- Lets see that again!Lets see that again!
Internet Society
IESGIAB
RFC Editor IANA Areas (7)
Working Groups
IETF
IRTF
How does the IETF Work?How does the IETF Work?
We do not believe in Kings, Presidents and We do not believe in Kings, Presidents and Voting. We believe in rough consensus and Voting. We believe in rough consensus and running coderunning code
Dave Clark, MIT, Former IAB memberDave Clark, MIT, Former IAB member
The IETF has a focus on developing standards where interoperabilThe IETF has a focus on developing standards where interoperability testing ity testing of conformant implementations of the standard, and use of the teof conformant implementations of the standard, and use of the technology chnology in production contexts form an integral part of the standards prin production contexts form an integral part of the standards processocess
How Does the IETF Work?How Does the IETF Work?
Proposed work items are aired at a BOF sessionProposed work items are aired at a BOF session•• Gather interest and supportGather interest and support
A work program is chartered by the IESG A work program is chartered by the IESG •• Working Group CharterWorking Group Charter
•• WG WG Chair(sChair(s) and Area Director) and Area Director•• Working Group statement of activityWorking Group statement of activity•• Schedule of milestonesSchedule of milestones
•• Periodic IESG review and Periodic IESG review and recharterrecharter as necessaryas necessary
IETF DocumentsIETF Documents
Internet DraftsInternet Drafts
•• http://www.ietf.org/1idhttp://www.ietf.org/1id--abstracts.htmlabstracts.html•• Individual submissionsIndividual submissions
•• draftdraft--<person><person>--<header><header>
•• Working Group DocumentsWorking Group Documents•• draftdraft--ietfietf--<working group><working group>--<header><header>•• Working Group documents denote some level of Working Group documents denote some level of ‘‘buybuy--inin’’ from the from the
community of interestcommunity of interest
IETF DocumentsIETF Documents
RFCsRFCs•• InformationalInformational•• Best Current PracticeBest Current Practice•• Standards TrackStandards Track
•• Proposed (good idea, clearly written, Working Group approved, Proposed (good idea, clearly written, Working Group approved, peer reviewed)peer reviewed)
•• Draft (interoperability tested, sound idea)Draft (interoperability tested, sound idea)•• Full (many people are / were using this technology)Full (many people are / were using this technology)•• Historic (no longer that useful)Historic (no longer that useful)
ENUMENUM
ENUM is a working group with the IETF Transport AreaENUM is a working group with the IETF Transport Area
ENUM (cont)ENUM (cont)
ENUM (cont)ENUM (cont)
Why ENUM?Why ENUM?
Because Because tpc.inttpc.int did not work!did not work!•• tpc.inttpc.int (c 1992) mapped E.164 numbers to A records (IP (c 1992) mapped E.164 numbers to A records (IP
addresses) to emulate fax deliveryaddresses) to emulate fax delivery•• Each new service required a new E.164 Each new service required a new E.164 --> IP address mapping> IP address mapping•• Did not scale to multiple services using a single mappingDid not scale to multiple services using a single mapping
ENUM is part of a broader IETF approach of splitting out ENUM is part of a broader IETF approach of splitting out the components of VOIP / PSTN interaction into discrete the components of VOIP / PSTN interaction into discrete efforts and addressing each component as a discrete efforts and addressing each component as a discrete technology standardization efforttechnology standardization effortENUM is not an end in itselfENUM is not an end in itself
The Good Bits of ENUMThe Good Bits of ENUM
E164.arpaE164.arpa•• Single mapping that is service independentSingle mapping that is service independent•• Each mapping can be associated with a collection of Each mapping can be associated with a collection of URIsURIs•• The mapping may be statically configured or dynamically The mapping may be statically configured or dynamically
generated (or both)generated (or both)•• Each end point of the DNS hierarchy populates the entry with Each end point of the DNS hierarchy populates the entry with
desired service entriesdesired service entries•• Each application selects compatible service entries from the setEach application selects compatible service entries from the set•• ENUM is independent of directory, call control, routing and ENUM is independent of directory, call control, routing and
transport considerationstransport considerations•• Its just a mapping from the E.164 domain into multiple URI Its just a mapping from the E.164 domain into multiple URI
service domainsservice domains
The Not So Good BitThe Not So Good Bit
The DNS is an issue in The DNS is an issue in itselfitself…………•• DNS is insecureDNS is insecure
•• TSIG, DNSSEC, PKI, etc may help, but when and how much?TSIG, DNSSEC, PKI, etc may help, but when and how much?
•• DNS is variably timedDNS is variably timed•• DNS is generally not well maintainedDNS is generally not well maintained•• DNS is generally not well synchronizedDNS is generally not well synchronized•• There is no There is no ““DNS says DNS says ‘‘nono’”’”, only an indistinct timeout, only an indistinct timeout•• Putting regular expressions in the DNS is an fascinating complicPutting regular expressions in the DNS is an fascinating complicationation•• But we have nothing better in terms of a very large distributed But we have nothing better in terms of a very large distributed
database to poke towards this problem spacedatabase to poke towards this problem spaceRemember:Remember:•• The DNS is a lousy kitchen sink. We have seen many proposals to The DNS is a lousy kitchen sink. We have seen many proposals to
““just put it in the DNSjust put it in the DNS””. Be very concerned whenever you hear this!. Be very concerned whenever you hear this!
ENUM is NOT everythingENUM is NOT everything
In particular, ENUM is NOT:In particular, ENUM is NOT:•• a directorya directory•• a search servicea search service•• a transport servicea transport service•• a voice encoding methoda voice encoding method•• a rendezvous protocola rendezvous protocol
All ENUM is a distributed partial mapping from All ENUM is a distributed partial mapping from E.164 addresses into a set of service points E.164 addresses into a set of service points identified via a URI identified via a URI labellinglabelling
The VOIP Gateway Model for The VOIP Gateway Model for enumenum
Most IETF work these days assumes a Most IETF work these days assumes a ‘‘reference architecturereference architecture’’ENUMENUM’’ss core reference architecture is VOIPcore reference architecture is VOIP--toto--VOIPVOIP
PSTNPSTN
Internet
VOIP Server
VOIP Served subnet
EnumService Point
The Gateway VOIP ModelThe Gateway VOIP Model
The single gateway model is simple:The single gateway model is simple:•• A PSTN / IP gateway maintains a mapping A PSTN / IP gateway maintains a mapping
between IP and E.164 addressesbetween IP and E.164 addresses
VOIPGateway
IP Net
PSTNPSTN
10.0.0.10 1234567810.0.0.11 1234567910.0.0.12 12345680
IP E.164
1. Call “12345678”
2. PSTN routes the call to 12345678 to the VOIP gateway
3. Gateway maps E.164 address “12345678” to IP 10.0.0.10
4. Gateway initiates a SIP session with 10.0.0.10
1234567810.0.0.10
The multiThe multi--Gateway VOIP WorldGateway VOIP World
Use PSTN / VOIP GatewaysUse PSTN / VOIP Gateways•• Each Gateway maps a set of telephone numbers to a Each Gateway maps a set of telephone numbers to a
set of served IP service addressesset of served IP service addresses•• Each Gateway knows only about locally served Each Gateway knows only about locally served
devicesdevices•• GatewayGateway--toto--Gateway calls need to be explicitly Gateway calls need to be explicitly
configured in each gateway to use IP or some private configured in each gateway to use IP or some private connection, or use the default of the PSTNconnection, or use the default of the PSTN
•• The PSTN currently is the glue that allows the VOIP The PSTN currently is the glue that allows the VOIP islands to interconnect with each otherislands to interconnect with each other
The multiThe multi--Gateway VOIP WorldGateway VOIP World
VOIP IslandsVOIP Islands•• E.164 numbers are only routable over the PSTNE.164 numbers are only routable over the PSTN•• Enterprise or carrier VOIP Enterprise or carrier VOIP diallingdialling plans cannot be remotely plans cannot be remotely
accessed by other VOIP network segmentsaccessed by other VOIP network segments
PSTNPSTN
Internet
The Core ENUM ProblemThe Core ENUM Problem
How can a VOIP gateway find out dynamically:How can a VOIP gateway find out dynamically:•• If a telephone number is reachable as an Internet device?If a telephone number is reachable as an Internet device?•• And if so, whatAnd if so, what’’s its Internet service address?s its Internet service address?
PSTNPSTN
Internet
Problem statements for ENUM (1)Problem statements for ENUM (1)
1.1. How do network elements (gateways, How do network elements (gateways, SIP servers etc) find services on the SIP servers etc) find services on the Internet if you only have a telephone Internet if you only have a telephone (E.164) number?(E.164) number?
Problem statements for ENUM (2)Problem statements for ENUM (2)
2.2. How can subscribers define their How can subscribers define their preferences for nominating particular preferences for nominating particular services and servers to respond to services and servers to respond to incoming communication requests?incoming communication requests?
The ENUM ObjectiveThe ENUM Objective
Allow any IP device to establish whether Allow any IP device to establish whether an E.164 telephone address is reachable an E.164 telephone address is reachable as an Internetas an Internet--described Servicedescribed Service•• And And …… what the preferred Service Point what the preferred Service Point
actually isactually is•• And if its an InternetAnd if its an Internet--reachable Service reachable Service
PointPoint…… what IP address, protocol address, what IP address, protocol address, port address and application address should port address and application address should be used to contact the preferred Service Pointbe used to contact the preferred Service Point
ENUM ResolutionENUM Resolution
The PSTN is a multi-service platformTo emulate this in IP, IP services associated with a single E.164 may be provided on a collection of different IP service pointsAn ENUM DNS request should return the entire set of service points and the associated service.
DNS Selection DNS Connection
E.164 address Set of URIs....
URI IP AddressTCP/UDP PortProtocol Address
Why Why URIsURIs??
URIsURIs represent a generic naming scheme to represent a generic naming scheme to describe IP service pointsdescribe IP service points•• Generic format ofGeneric format of
service:serviceservice:service--specificspecific--addressaddress
A URI in IP context is ultimately resolvable toA URI in IP context is ultimately resolvable totransport protocol (TCP/UDP) selectiontransport protocol (TCP/UDP) selectionIP addressIP addressPort addressPort addressAddress selector within the application sessionAddress selector within the application session
The Longer TermThe Longer Term
Telephone numbers are well accepted Telephone numbers are well accepted identifiers within their realm of applicationidentifiers within their realm of applicationAny collection of service Any collection of service URIsURIs can be can be linked against an ENUM entrylinked against an ENUM entry•• mail, www, mail, www, ircirc, , smssms,,……
E.164 as a common address substrate ?E.164 as a common address substrate ?
Use this number for any service+61 2 12345678
ENUM
tel:+61 2 62486165
mailto:[email protected]
tel:+61 2 12345678
Practical IssuesPractical Issues
Issues where the IETF has an active Issues where the IETF has an active interestinterest……•• Who should manage the e164.arpa zone?Who should manage the e164.arpa zone?•• Should there be one root for a single ENUM Should there be one root for a single ENUM
database or multiple databases for different database or multiple databases for different functions, number ranges, area codes or even functions, number ranges, area codes or even numbers?numbers?
•• How to secure the DNS to ensure that ENUM How to secure the DNS to ensure that ENUM answers are valid, timely and authoritativeanswers are valid, timely and authoritative
Practical IssuesPractical Issues
Issues where the IETF has a limited (if any) role Issues where the IETF has a limited (if any) role to play in ENUMto play in ENUM•• How to protect the privacy of the ENUM database?How to protect the privacy of the ENUM database?•• How to verify changes to the ENUM database?How to verify changes to the ENUM database?•• Should telephone number holders Should telephone number holders ‘‘optopt--inin’’ or or ‘‘optopt--outout’’
of the system?of the system?•• Portability and ownership of a phone number?Portability and ownership of a phone number?
•• Can I cancel all phone services and keep my phone number?Can I cancel all phone services and keep my phone number?
•• Compliance with legislative frameworkCompliance with legislative framework•• What is a What is a ““public telephone callpublic telephone call”” from a strict regulatory from a strict regulatory
perspective?perspective?•• Is there a valid need for yet another public identity space?Is there a valid need for yet another public identity space?