colombo, sri lanka, 7-10 april 2009 preferential telecommunications service access networks lakshmi...
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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