GRUPPO TELECOM ITALIA 3GPP release 8 IMS Implementation, Deployment and Testing Sophia Antipolis, France, Telecom Italia
Main focus The need to have IMS NNI profile, with the starting point outside 3GPP or the starting point in 3GPP Main aspects introduced in Rel-8, Rel-9 and Rel-10 Examples of nowadays applications of II-NNI profile
The need to have II-NNI
Drivers for IP interconnection The starting point to define IP interconnection is the IETF RFC 3261 (SIP: Session Initiation Protocol ) Hovever the document describes the signaling protocol to be used, but many implementations in order to provide IP services (telephone calls, multimedia distribution, multimedia conferences, etc.) are possible The need to have a common and shared SIP profile between different networks (and operators) grows in the evolution framework toward fixed & mobile all-ip networks Drivers of this evolution are Telephony VoIP TDM IP transport ISUP SIP enabling new IP services: Video, Presence, IPTV, Messaging,...
IP interconnection: some of the involved SDOs Internet (Unmanaged) ISP/ASP NGN Service Operator Service Layer Transport Layer Managed IP interconnection Service Layer Transport Layer NGN Service Operator
ITU-T Q.3401 (Q.NNI_profile): NNI profile based on SIP Logical Interfaces This interface is the scope of this Recommendation Wireless IP Phone Service Control Functions Provider A VoIP Transport Functions Service Control Functions Transport Functions Provider B VoIP Wireless IP Phone SS7 MG MG SS7 PSTN PSTN Bearer (RTP/IP) Signall (SIP)
ITU-T The Q.3401 recommendation contains a service-level profile, i.e. SIP/SDP interface description, between two network operators (NNI signalling profile), where the two different network operators may support different SIP/SDP profiles (i.e. they differ in terms of the SIP extensions, SIP information elements, and SDP lines which are supported) The proposed profile is derived from the IETF RFC SIP profile (RFC 3261) The defined NNI is essentially based on voice services basic profile (no supplementary services)
ETSI TISPAN Rel2: SoIx and Coix Session Border Controller Service Oriented Interconnection (SoIx): linking of NGN domains including control signalling Interconnection Service Aware Connectivity-oriented Interconnection (CoIx): linking based on simple IP connectivity Interconnection Service Unaware
Main aspects introduced in 3GPP
3GPP: IP interconnection service requirements A work item covering service requirements was approved in SA1 ( Requirements for SoIx requirements IPX requirements Advanced IP Interconnection of Services ) To specify the technical requirements for carrier grade inter-operator IP Interconnection of Services for the support of Multimedia services provided by IMS and for legacy voice PTSN/PLMN services transported over IP infrastructure (e.g. VoIP) Service requirements should take into account the new and developing convergent interconnect models currently being developed outside 3GPP GSM A IPX TISPAN SoIX stage 2 & 3 II-NNI TS 23.228 Annex K TS 29.165 SA1 service requirements TR 22.893 stage 2 & 3 SIP-I NNI TS 29.235
3GPP activities on IP interconnection (1/2) IP Interconnection is being defined in Release 8 between two IMS systems (II-NNI) IMS Border SIP NNI Controller Border Controller IMS Border controller for: Topology hiding, SIP Routing Screening and policy, Security... IP interworking is defined in Release 7 between CS PLMN and external SIP-I networks. This work is the basis for the SIP-I NNI done in Release 8 CS Border SIP-I NNI Controller Border Controller CS SIP-I or BICC or ISUP SIP-I or BICC or ISUP
3GPP activities on IP interconnection (2/2) CS-IBCF (CS-TrGW) IBCF (TrGW) S-CSCF (GW) TS 29.235 (nodes) TS 23.231 29.231 (protocol) old ITU-T Q 1912.5 (also for ISUP and BICC) TS 23.228 (architecture) TS 29.165 (profile) TS 24.229 (protocol) TS 29.162 TS 29.162 II-NNI SIP-I network IBCF (TrGW) 3GPP IMS network SIP network (or IMS nw without IBCF) 3GPP network Border element
IP interconnection between two IMS networks (II-NNI) Based on TISPAN and ITU-T experiences, 3GPP started to define an NNI specification for the Inter-IMS Network to Network Interface (II-NNI) An initial feasibility study (2H 2007) was done. TR 29.865 IMS inter-operator service interconnection interface identifies the 3GPP protocols and profiles appropriate to NNI control & user plane interfaces Since 2008 the first version of the reference specification for II-NNI (3GPP MTS 29.165) was provided starting from Release 8 S-CSCF I-CSCF BGCF BGCF I-CSCF S-CSCF P-CSCF Mx Mx IBCF Mx II-NNI Mx Mx IBCF Mx Mx P-CSCF MSC Server enhanced for ICS Signalling Bearer Mx Ix TrGW IM CN subsystem network A Ici Izi Mx Ix TrGW IM CN subsystem network B MSC Server enhanced for ICS
Justification of II-NNI The IM CN subsystem enables the support of basic voice over IP calls as well as other multimedia services (e.g. video calls). All of these services require a well defined Inter-IMS Network to Network Interface (II-NNI) to support worldwide interoperable communication between IMS networks. Furthermore a standard II-NNI will help IMS networks to comply interoperability requirements defined within national and international regulatory framework TS 29.165 proposes an Inter-IMS Network to Network Interface (II-NNI) signalling profile in order to provide a standard reference for service interconnection between two IMS networks The goal is not to define new protocol specifications across these interfaces (already done in TS24.229), but to identify the protocols and profiles produced elsewhere in 3GPP that are appropriate to these interfaces.
II-NNI profile in Rel-8 II-NNI (TS 29.165) CONTROL (Ici) IETF basic profile SIP RFC 3261, SDP RFC 2327/3264 RFCs to be used Supported SIP methods & headers P-header valorization for II-NNI Numbering, Naming and Addressing This approach guarantees the IETF basic session setup Starting from TS24.229 MEDIA (Izi) Media Codec negotiation media transcoding IPv4/IPv6 interworking Protocols Codecs proposed in 3GPP TS 26.114 and ETSI TS 181 005
Example of supported methods Item Method Ref. II-NNI Sending Receiving 1 ACK request [13] m m 2 BYE request [13] m m 3 BYE response [13] m m 4 CANCEL request [13] m m 5 CANCEL response [13] m m 5A INFO request [28] o o 5B INFO response [28] o o 8 INVITE request [13] m m 9 INVITE response [13] m m 9A MESSAGE request [19] o o 9B MESSAGE response [19] o o 10 NOTIFY request [20] c1 c1 11 NOTIFY response [20] c1 c1..
II-NNI profile in Rel-9 II-NNI (TS 29.165) CONTROL (Ici) IETF basic profile SIP RFC 3261, SDP RFC 2327/3264 RFCs to be used Supported SIP methods & headers P-header valorization for II-NNI Numbering, Naming and Addressing Suppl serv. profiles at interconnection Support of Major Capabilities Rel-8 profile update MEDIA (Izi) Media Codec negotiation media transcoding Interlavoro IPv4/IPv6 Protocols
Example of major capabilities Item Capability over the Ici Reference item in 3GPP TS 24.229 [5] for the profile status Profile status over II-NNI UA Role (NOTE 1) Proxy role (NOTE 2) Basic SIP (IETF RFC 3261 [13]) 1 registrations 1, 2, 2A - c2 2 initiating a session 2B, 2C, 3, 4 - m 3 terminating a session 5 3 m 4 General proxy behaviour - 4, 5, 14, 15, 19F n/a 5 Forking of initial requests 9,10 6 m 8 Timestamped requests (Timestamp header field) 6 - m 9 Presence of date in requests and responses (Date header field) 11 9 m 10 Presence of alerting information data (Alert-info header field) 12 10 o 15 Support and handling of the Call-Info header field - 19C, 19D m 16 Support of the Contact header field in 3xx response - 19E m Extensions to basic SIP 17 draft-ietf-sipcore-info-events-08 [39]: SIP INFO method and package framework 13 20 o 17A draft-ietf-sipcore-info-events-08 [39]: legacy INFO usage 13A 20A o 20 IETF RFC 3312 [40] and RFC 4032 [41]: integration of resource management and SIP (Preconditions framework) 16 23 o 21 IETF RFC 3311 [23]: the SIP UPDATE method 17 24 m
II-NNI profile in Rel-10 (still in progress) II-NNI (TS 29.165) CONTROL (Ici) IETF basic profile SIP RFC 3261, SDP RFC 2327/3264 RFCs to be used Supported SIP methods & headers P-header valorization for II-NNI Numbering, Naming and Addressing Suppl serv. profiles at interconnection Support of Major Capabilities Rel-8 and Rel-9 profile update Dynamic profile Support of additional services beyond the supplementary services (ICS, SRVCC, IUT and MSC Server mid-call assisted feature, Presence, etc) MEDIA (Izi) Media Codec negotiation media transcoding Interlavoro IPv4/IPv6 Protocols
II-NNI nowadays applications
Impacts of II-NNI profile in other standards RCS (Rich Communication System) Interworking Guidelines (GSMA) Document IR.90 defines that the II-NNI forms an important part of RCS NNI since RCS heavily utilizes IMS core system as specified by 3GPP to perform a number of key duties such as handling of SIP signalling, authentication, authorization, charging and routing support. IREG (GSMA Inter-working Roaming Expert Group ) There is a collaboration between 3GPP CT3 and IREG in order to evaluate if to use TS 29.165 per IP interconnect scenarios defined in GSMA PRD IR.34 ed interested by II-NNI aspects ETSI TISPAN In TS 184 011 Requirements and usage of E.164 numbers in NGN and NGCN (specification under approval) the TS29.165 is mentioned as reference document
Conclusions II-NNI is the method suggested to the operators and authorities in order to provide an effective, stable and deep analysed standard for interconnecting IMS networks II-NNI could be used also for interconnecting IP networks that use a SIP profile, taking into account that SIP profile is still existing (based on RFC 3261) but this is not enough suited as NNI profile Major effort should be done to trasform TS 29.165 as an ETSI standard (ES or EN) to adopt the defined profile between the regulatory bodies to use TS 29.165 as reference documentaton for interoperability tests