1January 2006 Richard Stastny

Developments around

Infrastucture ENUMand their relevance on NGNs

Workshop on NGN Interconnection and Numbering

TRIS – TISPAN WG4Copenhagen, 18. January 2006

Richard Stastny, ÖFEG*

* The opinions expressed here may or may not be that of my company

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Content

• NGN/IP Interconnect – VoIP Peering– Some definitions

• What is ENUM?• What kind of ENUM?

– Infrastructure ENUM

• Recent IETF developments– ENUM WG– SPEERMINT WG

• Benefits in a nutshell

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Definitions

• What are NGNs?– IP-based “networks”– “Service provider” “networks” offering real-time or

near realtime IP communications– “Enterprise networks”– etc. Administrative Domains

• What is Interconnection between NGNs?– a user registered in one administrative domain is

able to contact (establish a session to) an user registered in a different administrative domain by using a Public User Identity (Address-of-Record, E.164 Number)

– preferably via IP

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NGN/IP Interconnect (VoIP Peering)

• If we take the All-IP paradigm seriously, we have two basic requirements:– Any real-time communication originating on IP and

terminating on IP MUST stay on IP end-to-end– This implies, it MUST NOT use the PSTN/ISDN to

interconnect.

• Benefits are:– improved end-to-end functionality (BB codecs, IM,

video, conferencing, presence, …)– Improved end-to-end QoS– No additional cost beside of IP-access– convergence possible at the end-user’s device

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Example IMS (TS 23.228)

• Public User Identities– something one may put on a business card

a SIP URI or a TEL URI (in E.164 format)

• Routing* within IMS shall use SIP URIs– (converted via DNS to IP addresses – RFC3263)

– TEL URIs will require conversion to SIP URIs (via ENUM) Interconnection between IMS must be possible by using SIP URIs only

* Routing = finding the next hop

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Possible Public User Identities

• E.164 numbers• SIP URIs defined by provider:

– sip:4319793321@telekom.at– sip:richard.stastny@aon.at

• SIP URIs with self-provided domains:– sip:8431@kapsch.net– sip:richard.stastny@oefeg.at

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• Electronic or E.164 NUMber mapping is defined by the Internet Engineering Task Force (IETF) in RFC3761 as:

• the mapping of „Telephone Numbers“ to Uniform Resource Identifiers (URIs) using the Domain Name System (DNS) in the domain e164.arpa

– URIs are used to identify resources on the Internet (e.g. http://enum.nic.at )

• The purpose of ENUM is to enable the convergence between the PSTN and the Internet

ENUM is defined by the IETF

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ENUM in a nutshell

• take an E.164 phone number +43 720 203 211

• turn it into a FQDN 1.1.2.3.0.2.0.2.7.3.4.e164.arpa.

• returns list of URIs sip:richard.stastny@iphone.at

• query the DNS (for NAPTR)

mailto:richard.stastny@oefeg.at

sms tel:+436644204100

IN NAPTR 100 100 "u" “E2U+sip“ !^.*$!SIP:richard@iphone.at! .

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The basic idea of ENUM (RFC3671)

• The basic idea of ENUM was – to allow end-users – to opt-in with their EXISTING phone-

numbers on the PSTN – into e164.arpa – to provide OTHER end-users with the

capability – to look up contact URIs on the Internet the

above end-user wants to link to this number

• This kind of ENUM is called User ENUM

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SIP Session establishment

sip:alice@providerA.net

providerA.net providerB.net

SIP server

SIP server

sip:eve@providerA.net sip:eve@providerB.net sip:bob@providerB.net

sip:bob@providerB.net

session

DNS SRV lookupproviderB.net

sip:bob@providerB.net

IP –based networkIf this does not work, forget ENUM

DNS

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E.164 Session establishment

sip:alice@providerA.net

providerA.net providerB.net

SIP server

SIP server

sip:eve@providerA.net sip:eve@providerB.net sip:bob@providerB.net

tel:+43780420410

session

DNS SRV lookupproviderB.net

sip:bob@providerB.net

DNS

IN NAPTR 0.1.4.0.2.4.0.8.7.3.4.e164.arpa. ?

... NAPTR ... "!^.*$!sip:bob@providerB.net!"

What is ENUM adding?

ENUM DNS

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What are the Benefits of ENUM?

• ENUM is using the DNS– it’s there, it works, it’s global, it scales, it’s reliable,

it’s open, anyone can use it…– saving CAPEX

• Enables the originating administrative domain to do an All Call Query (ACQ) to find the destination network– Ultimate solution in Number Portability

• Provisioning is done only by the destination (recipient) administrative domain for the E.164 numbers this domain is hosting– Saving OPEX

• Enables all multimedia (MM) services for E.164 numbers for all sessions on IP end-to-end– Enables convergence (whatever that means)

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So what ENUM should be used?

The ENUM Babuschka‘s

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The “ENUMs”

• User ENUM• Private ENUM• Operator ENUM• Enterprise ENUM• Federation ENUM• Carrier ENUM• Infrastructure ENUM• EMINEM

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User ENUM

• User ENUM requires– country opt-in– end-user opt-in

• “Service providers” have no say in User ENUM

• So Service Providers using IP-based technology need other solutions to be able to Interconnect – via IP-based technology and – using E.164 Numbers

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Private ENUM

• Also called:– Operator ENUM– Enterprise ENUM

• An administrative domain is setting up their own private ENUM DNS– May be used in addition to other solutions to route

within own network

• But does not solve the Interconnect problem with other administrative domains AND– requires extensive provisioning

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Federation ENUM

• This is currently how “service providers” interconnect on IP:

• Variants:– Private ENUM in a “walled garden” extranet (GSMA)– SIP Exchange with restricted access on the Internet

(Cable providers, XConnect, SIP-IX, …)– public tree not in „e164.arpa“ (e164.info)

• Advantages:– No user opt-in, NO REGULATORS INVOLVED,

intrinsic peering agreements, savings in CAPEX, OPEX, MM-services

• Disadvantages:– limited reach, – no global solution, – how to peer with other federations?

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Public Infrastructure ENUM

• If Infrastructure ENUM is intended to allow the mapping of any E.164 number – that can be reached via IP – even if it terminates on the PSTN– to a SIP URI,

• Infrastructure ENUM must be in the public DNS.

• But this is useless, if the resulting SIP URI cannot be reached

• So for Infrastructure ENUM also a global IP Interconnect (VoIP Peering) regime is required.

• ENUM is an applet to VoIP Peering

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Standardisation in IETF

• Two recent major developments in IETF regarding (VoIP) Interconnect:– ENUM WG extended scope to include

Infrastructure ENUM– Voipeer BoFs to create new SPEERMINT WG

• Session PEERing for Multimedia INTerconnect

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Separation of Scope

• The ENUM WG is primarily concerned with the acquisition of Call Routing Data (CRD) e.g. a SIP URI,

• while the SPEERMINT WG is focused on the use of such CRD.

• Importantly, the CRD can be derived from ENUM (i.e., an E.164 DNS entry), or via any other mechanism available to the user.

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Scope ENUM and SPEERMINT

InfrastructureENUM

PolicyDatabase

Number

SIP URI

Routing Parameter

ENUM Lookup

Policy Lookup

I-ENUM

SPEERMINT

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Current I-Ds in ENUM WG

• Carrier/Infrastrucure ENUM Requirements – draft-lind-infrastructure-enum-reqs-01

• Combined User and Carrier ENUM in the e164.arpa tree – draft-haberler-carrier-enum-01

• IANA Registration for an Enumservice Containing PSTN Signaling Information– draft-ietf-enum-pstn-02

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Current I-Ds in SPEERMINT

• Terminology for Describing VoIP Peering and Interconnect – draft-meyer-voipeer-terminology-01

• Publishing SIP Peering Policy – draft-lendl-sip-peering-policy-00– This documents proposes the use of DNS entries to

publish a SIP proxy's policy for accepting incoming calls. Such published policies can be used to selectively establish peering relationships between VoIP service providers.

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Benefits in a nutshell

• The major benefits of Infrastructure ENUM and SPEERMINT for (VoIP) carriers and (VoIP) service providers is to save costs:

• Minimal CAPEX for setting up the required infrastructure to provide the routing data

• Minimal OPEX for maintaining routing data:– Announce the E.164 numbers you host (in ENUM)– Announce the domains you host (in DNS)– (make bilateral or multilateral peering agreements)– Query ENUM and DNS to find any other destination

provider

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The End

Thank you

Richard StastnyÖFEG

+43 664 420 4100

richard.stastny@oefeg.at

http://voipandenum.blogspot.com