world class standards common ims in tispan sa3litispanwg7_08_02 scott cadzow

World Class Standards

Common IMS in TISPAN

SA3LITISPANWG7_08_02

Scott CADZOW


IMS in NGN

NGN brings together many access technologies to a common service enabling platform IMS serves as the common service enabling platform

Access technologies are managed in their own abstraction layer NASS (Network Access Sub-System)

QoS and access privileges are managed through an additional abstraction layer RACS (Resource and Admission Control System)

Users may use many access technologies to access services and may use them concurrently or sequentially within a single session

This requires IMS to be supportive of any NASS or RACS technology Has to ensure that NASS/RACS requirements are devolved to the

correct layer

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The goals for NGN LI standardisation

Conformance to International User Requirement As annex to COM 96/C329/01: "European Union Council Resolution

COM 96/C329/01 of 17 January 1995 on the Lawful Interception of Telecommunications"

As found in TS 101 331 "Telecommunications security; Lawful Interception (LI); Requirements of Law Enforcement Agencies“

Compliance with objectives of ECN&S regulatory framework The NGN consists of many ECN and many ECS with loose

relationships

Clear identification of Points of Interception What is available at different PoI Correlation between different PoI Prevention of duplication of invocation of interception at PoIs


Documents to integrate

TISPAN TS 187 005, in draft for NGN-R2

3GPP SA3-LI 33.107, stage 2 in draft for R8 33.108, stage 3 in draft for R8

TC LI TS 102 232, handover to IP networks ES 201 671/TS 101 671, handover to Circuit Switched networks

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Technologies supported by the NGN

Separation of ECN and ECS ECS technologies:

IMS (care of 3GPP) PES (ISDN/PSTN on soft-switches) IPTV Corporate services

ECN technologies: ADSL PLMN Radio (care of 3GPP) LAN radio (mostly care of 3GPP) PSTN/ISDN

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Interception in the NGN - identity

ECS identity MSISDN E.164 SIP-url (sip-user@sip-domain) Other …

ECN identity IMSI Chap credential and identity

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Interception in the NGN - signalling

ECS IMS (SIP) signalling

• REGISTER (equivalent to MAP, found at HLR/VLR like entities)• INVITE, ACK, BYE, CANCEL, OPTIONS (found at CSCF entities)

PES/PSS• ISDN emulation signalling found at Signalling gateways (H.248)• SIGTRAN, SIP-I

ECN Access signalling (no service), CHAP, PPP etc.

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Interception in the NGN - content

ECS No traffic content Some extended signalling content in SDP/SIP

ECN IP traffic content

• TCP, UDP, RTP

Non-IP traffic content

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Problems in NGN, ECN&S interception

Correlation across ECN/ECS boundary IMS into NASS via RACS (Gq’) for QoS transport control Resource requests from ECS to ECN not personalised

Dynamic assignment of NASS and RACS without IMS intervention One service many transport offerings

Ownership break across ECN/ECS boundary (one CSP for each of ECN and ECS) No correlation as there is no common visibility to CSP

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IMS interception

IMS is an instance of ECS technology Independent of ECN technologies

IMS is a platform No services per-se

Expectation from NGN Clear identification of PoI for various IMS capabilities Common capability for all IMS implementations

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Concerns to be addressed

Structure of IMS interception One clause for any technology (IMS is an ECS technology and any

ECN technology can/should be able to access it) Reference from TS 187 005 to 33.107 Annex showing normative application from TS 187 005 to 33.108

Timetable for IMS interception Required for NGN-R2 TS 187 005 to be finalised very soon and needs to have IMS

interception included• Ideally by reference to 33.107 and 33.108• If not by reference then in a transferable way (i.e. defined in TISPAN for

movement to 33.107 and 33.108 when appropriate)

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