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Voice over IP Protocol Update

Voice over IP Protocol Update

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Voice over IP Protocol Update

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  1. Voice over IP Protocol Update Michael Rubin mrubin@sonusnet.com

  2. Clear Business Advantages Revenue/Min. Traditional Traditional Cost/Min. Operational Savings:Per-port cost  50%Operating costs  45%CO space reqts  90% Packet Time

  3. Voice Over Packet Gateways Packet • Must convert between circuit and packet Circuit Devices

  4. Wide Range of Gateways Access Gateways IAD IAD LAG CM SS7/C7 Circuit DSLAM CMTS • POTS or PABX interfaces • 1-30 calls simultaneously Carrier Gateway • Support SS7 trunks • Up to 100,000 calls or more simultaneously

  5. Call Control • Need to manage calls between gateways

  6. Network Model Zone 5 Zone 1 Operator 2 Zone 4 Zone 2 Zone 3 Operator

  7. In the Beginning . . . • H.323 • An international (ITU) standard • Developed for LAN videoconferencing • IP transport • PC clients Packet

  8. H.323 Operation Call RAS - registration, admissions, status Call Signaling - setup, tear down H.245 - channels, capabilities/preferences, flow control RTP - audio data Gatekeeper Gatekeeper GW GW H.225 - multiplexing, sequence numbering, error handling

  9. H.323 Analysis • Used by older devices • Supports only making connections • Other features must be implemented in gateway • Authorization codes, accounting codes, PINs • Two-stage dialing • Announcements, digits collection, etc. • No way for Gatekeeper to tell Gateway what to do

  10. H.323 Analysis • Too inefficient for large carrier gateways • Many different connections (H.225, H.245, RTP) • Heavy processing (ASN.1 message format) • No support for end-to-end SS7 • Too complex for small access gateways • Gateway heavily involved in call setup • Too expensive to implement features

  11. SoftSwitch Architecture • Provisioning • Services • Routing • Control Softswitch IAD IAD LAG CM SS7/C7 Circuit DSLAM CMTS Control Protocol • Media conversion • Echo cancellation • Audio processing

  12. Why a New Model? • Component flexibility • Soft switch and MG can be from different vendors • Can mix MGs from different vendors • Central control • Lower cost • Soft switch benefits from Moore’s Law • Intelligence (=cost) removed from MG

  13. Gateway Control Protocols Coordination • Industry standards • Internet Protocol Device Control (IPDC) • Media Gateway Control Protocol (MGCP) • Standards Activity • IETF Megaco Working Group • ITU Study Group 16 (H.248)

  14. Softswitch Analysis • Best for small gateways • Features implemented in softswitch • Central provisioning • Minimum requirements in gateway • Gateways can be very inexpensive • Adaptable for large carrier gateways • Efficient processing • Can support end-to-end SS7 • Large networks can have multiple softswitches

  15. From the Internet . . . • Session Initiation Protocol (SIP) • An IETF recommendation • Used to initiate multimedia sessions • Works with other protocols (SDP, RTP, etc.) Packet

  16. SIP Evolution • Many efforts to apply to telephony • PSTN-Internet (PINT) working group • IP Telephony (IPTel) working group • Distributed Call Signaling (DCS) efforts • Inter-Domain Signaling (SIP-T) • Vocal Internet following • SIP devices starting to appear • Interoperability “bake-offs”

  17. SIP Analysis • Much more “light-weight” than H.323 • Supports call signaling only • Used for interoperability with edge devices • PCs • IP Phones/PABXs • Low-end gateways • IADs

  18. Market Reality • Softswitch architecture has won for carrier core networks • Required in virtually all carrier and vendor architectures • Long-term direction is Megaco/H.248 • Most softswitches and devices currently implement MGCP

  19. Softswitch Must Be Multiprotocol PSTN IAD CM CPE LAG CMTS DSLAM SoftSwitch CL4 CL5 SIPH.323 Other Zone/Network MGCP, H.248 PBX

  20. Call Management Standards • Within a Zone • Zone-to-Zone • Operator-to-Operator

  21. Inter-Domain Signaling Softswitch Softswitch H.323 (ITU/ETSI) SIP-T (IETF) BICC (ITU) MG MG MG MG MG MG Not addressed by MGCP, H.248, etc.

  22. Inter-Domain Signaling Analysis • Likely to differ by operator • Supports call signaling only • Needs to support end-to-end SS7/C7

  23. Need to support both large carrier gateways and small devices Softswitch model better than H.323 for both Megaco/H.248 the long term gateway control protocol H.323 and SIP will be used for customer packet devices Softswitch must mediate between them Summary

  24. Thank You Michael Rubin Sonus Networks, Inc. 5 Carlisle Road Westford, MA 01886, Phone: 1.978.589 8422 Fax: 1.978.392.9118 mrubin@sonusnet.com