Colombo, Sri Lanka, 7-10 April 2009

Preferential Telecommunications Service

Access Networks

Lakshmi Raman,Senior Staff Engineer Intellectual Ventures

USA

FORUM ON NEXT GENERATION STANDARDIZATION

(Colombo, Sri Lanka, 7-10 April 2009)

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Overview

Preferential Telecommunications Service*

NGN considerations for PTS

Capabilities and Mechanisms to support PTS

Requirements for PTS in NGN Access Networks

Signaling and Control support in Cable Access

ITU Recommendations in support of PTS

* Emergency Telecommunications and Preferential Telecommunications are used to represent the concept in different ITU Recommendations.

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PTS Overview

Preferential Telecommunications Service

CharacteristicsCategoriesConsiderations with NGN versus Circuit-Switched Network Environments

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PTS CharacteristicsAssured capabilities to enable operations in the event of impacts to Telecommunications infrastructures

Examples of PTS

Telecommunications for disaster relief

National/Regional/Local Emergency/Public Safety

Early Warning Systems to individuals exposed to hazards to avoid or reduce risks

Categories*

Individual to authority

Authority to individual

Authority to authority

Individual to individual

* ETS ITU Recommendation focuses on authority to authority

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NGN versus Circuit Switched Environment

C ircuit Switched Packet Sw itched (N G N )

A dm ission control utilizes tight coupling between signaling and media resources

M any applica tions do not signal bandw idth requirem ents and signaling and m edia are not coupled

C onstant bit ra te de livery of a ll m edia traffic w ith uniform bandw idth

D elivery uses dynam ically adjusted ra tes to meet variable bandw idth requirem ents of applica tions/services

R eserved bandw idth per flow D ifferent packet flow s are sta tistica lly m ultiplexed on shared bandwidth; bursty traffic charac teristics re lay sharing resources and queues (rea lized as best effort service)

Separate control and data traffic

Shared resource for resource control and data traffic

Provisioning of PTS capabilities is not entirely straightforward, obvious or simple. A simple transposition from the circuit-switched world is not appropriate.

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Capabilities and Requirements Enhanced priority treatment

Secure networks

Location Confidentiality

Service Restoration Priority

Network connectivity

Interoperability

Mobility

Ubiquitous coverage

Survivability/endurability

Real-time transmission to support: voice/real-time text and video/imagery(where bandwidth is available)

Non-real-time transmission to support:messages / non-real-time streams (audio/video)

Scaleable bandwidth

Reliability/availability

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MechanismsIdentification and marking of the PTS traffic

Example mechanisms in Service Stratum: SIP Resource Priority header,call priority designator in ITU-T H460.4.priority indicator in H 248.1

Admission control policy

Allowing requests from PTS traffic over regular traffic

Bandwidth allocation policy

Example in Transport Stratum: Resource Reservation Protocol, DSCP code points

Authentication and authorization of bona-fide PTS users

Use of PINs, user and subscription profiles

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Access Networks Requirements

Different Access Technologies

Cable,xDSL, Wireless,optical

Signaling and Control Requirements

Recognize PTS traffic

Provide preferential/priority access to resources/facilities

May require mapping of security levels when different values are used in different domains

Support preferential/priority routing of PTS traffic

Preferential/priority establishment PTS sessions/calls

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Access Networks Requirements (2)

Security Considerations

Protecting all aspects of PTS, signaling and control, bearer/media, and management related data and information

Establishment and enforcement of security policies and practices that are specific to PTS

Authentication users with priority to prevent denial of service attacks by non authorized users

A minimum of two mechanisms recommended for IPCablecom networks

Implementation of mitigation capabilities to provide protection against various security threats

Protecting end-to-end communications when traversing multiple provider domains

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Priority Mechanisms for IPCablecom2 Networks

Priority Labeling

RTP does not provide support for labeling packets

Priority Signaling

SIP Resource Priority header in the user agent

Two options are possibleSIP UA include the R-P HeaderProxy Call Serving Control Function (P-CSCF) translates a code value to appropriate R-P Header value

Priority Enabling Mechanisms

Data link layer support for DOCSIS Service Flows according to traffic priority set for PTS sessions

Session layer status set up propagating the priority status to all relevant entities in the network

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Example Call Flow in IPCablecom 2 networks

SIP UA CM P-CSCFCMTS PCRF

(A1) Pref Priority INVITE SDP offer (A2) Contention

Request

(A3) Grant

(A5) INVITE Request

(A6) Recognize Pref Call

(A7) Bearer Reserve Req. {Reservation Priority AVP}

(A8) Gate-Set(A9) DSA-REQ

(A10) DSA-RSP

(A11) DSA-ACK(A12) Gate-Set ACK (A13) Bearer

Reserve Req. Response

(A14) INVITE with RPH

(C1) 183 with RPH(C2) 183 Session Progress with RPHSDP answer

Pref-ID +DNS Request

(A4) Priority Signalling Service Flow

(C3) Priority Signaling Svc. Flow

(C4) Bearer Activate Req. {Reservation Priority AVP}

(C5) Gate-Set(C6) DSC-REQ

(C7) DSC-RSP

(C8) DSC-ACK(C9) Gate-Set ACK (C10) Bearer

Activate Req. Response

(D2) Contention Request

(D1) PRACK

(D3) Grant

(D4) Priority Signaling Svc. Flow

(D5) PRACK

Normal Call setup Continues

Media Bearer (RTP) with priority DSCPMedia Bearer (RTP)Priority Bearer

Svc. Flow

All Gate-set messages shown represent a pair of Gate-Set messages: one for uplink traffic and one for downlink traffic. Cable Access Service Flows are unidirectional.

Creates bearer service flows in the Admitted state. Note: bearer data, if transmitted primary service flow. CMTS does not stop data.

Moves the bearer service flows to the Active state to allow transmitting bearer data packets on the prioritized flow.

The P-CSCF sends a message to the PCRF to reserve the bearer resources.

The P-CSCF activates the flows for the previously reserved resources.

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PTS/ETS NGN ITU-Recommendations

ITU-T Y.1271, Framework(s) on Network requirements and capabilities to support emergency telecommunications over evolving circuit and packet switched networks

ITU-T Y.2205, Next Generation Networks, Emergency Telecommunications- Technical Considerations

ITU-T H.460.4, Call priority designation and country/international network of call origination identification for H.323 Priority calls

ITU-T H.248.1, Gateway control protocol: Version 3.

ITU-T Y.2111, Resource and admission control functions in Next Generation Networks.

ITU-T J.260, Requirements for Preferential Telecommunications over IPCablecom networks

ITU-T J.261, Framework for implementing preferential telecommunications in IPCablecom networks

ITU-T J.262, Specifications for Authentication in Preferential Telecommunications over IPCablecom2 networks

ITU-T J.263, Specifications for Priority in Preferential Telecommunications over IPCablecom2 networks