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ADEC Voice Services Panel Discussion. Walt Magnussen Ph.D Texas A&M University Director for TAMU Internet2 Technology Evaluation Center April 27, 2005. Voice Services – The issue. Voice signals are encoded into digital packets (Codec)

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ADEC Voice Services Panel Discussion


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    1. ADEC Voice Services Panel Discussion Walt Magnussen Ph.D Texas A&M University Director for TAMU Internet2 Technology Evaluation Center April 27, 2005

    2. Voice Services – The issue • Voice signals are encoded into digital packets (Codec) • Packet is put into Internet Protocol (IP) frame for delivery • The Internet is a “best effort delivery system”

    3. Network Impairments • Packet loss • Jitter • Latency • How much is to much ???

    4. Other issues • Interoperability H.323 vs. SIP • Gateway PSTN to VoIP • Fire walls, NAT, packet shapers, IPSec, VPNs and other mean and nasty things. • Many opportunities for research 

    5. VoIP Phone Codec Testing Internet2 Technology Evaluation Center Department of Telecommunications Texas A&M University, College Station, TX 77843 Goals and Objectives • Evaluate various VoIP codecs • Compare various vendor implementations of the codecs • Research Codec Testing Algorithms Contact: Walt Magnussen Email: telecom@tamu.edu http://itec.tamu.edu

    6. VoIP Phone Codec Testing Internet2 Technology Evaluation Center Department of Telecommunications Texas A&M University, College Station, TX 77843 Design and Implementation Network Diagram Network Lab Setup Above: Graduate students Clark Xu Yang and Karthik Kannan analyze results from voice quality test. • Ixia traffic generator loads one side of the network with generic TCP traffic. • Call is placed from one IP phone to the other. • Anritsu Data Quality Analyzer measures packet loss between the two phones. • Agilent VQT transmits audio file though one IP phone and receives the audio file with potential missing packets though the other IP phone. • VQT then compares the two audio files and returns a call quality score (MOS). Contact: Walt Magnussen Email: telecom@tamu.edu http://itec.tamu.edu

    7. VoIP Phone Codec Testing Internet2 Technology Evaluation Center Department of Telecommunications Texas A&M University, College Station, TX 77843 Results and Conclusions • G.729 codec degraded at a faster rate when packet loss exceeded 5% • Higher bandwidth applications such as LANs or MANs should use G.711 as default • G.711 codec provided acceptable audio quality (MOS >3.0) up to 5% packet loss. • GIPS codec significantly outperformed G.711 before declining in audio quality at 15%packet loss. Contact: Walt Magnussen Email: telecom@tamu.edu http://itec.tamu.edu

    8. ADEC VoIP Beta Testing American Distance Education Consortium (ADEC) Tachyon Networks, Inc. Internet2 Technology Evaluation Center Department of Telecommunications Texas A&M University, College Station, TX 77843 Goals and Objectives • Conduct instrumented tests of Tachyon’s VoIP capability. • Determine optimal configuration parameters and assess performance over satellite links for VoIP equipment from a variety of vendors. • Monitor field tests at multiple ADEC sites in a normal operational environment. Contact: Walt Magnussen Email: telecom@tamu.edu http://itec.tamu.edu

    9. ADEC VoIP Beta Testing American Distance Education Consortium (ADEC) Tachyon Networks, Inc. Internet2 Technology Evaluation Center Department of Telecommunications Texas A&M University, College Station, TX 77843 Concept and Design • Call is placed from SAT phone to LAN phone • Contending data is also transmitted over satellite link • Voice and contending data travels from Tachyon facilities in San Diego to the Internet2 network via the San Diego Supercomputing Center • Voice and data gets routed to Texas A&M University Network • Voice and data reaches the ITEC LAN switch • Data Quality Analyzer measures packets lost over the entire network • Voice Quality Tester takes transmitted voice and received voice then returns back a score (MOS) ranking the call quality Contact: Walt Magnussen Email: telecom@tamu.edu http://itec.tamu.edu

    10. ADEC VoIP Beta Testing American Distance Education Consortium (ADEC) Tachyon Networks, Inc. Internet2 Technology Evaluation Center Department of Telecommunications Texas A&M University, College Station, TX 77843 Lab Implementation Graduate student Karthik Kannan places a call from the satellite phone to the local network phone. Packetized voice conversation travels to Tachyon indoor units. Lab Testing Setup Tachyon Satellite Indoor Units Tachyon Satellite Antenna Packetized voice conversation is converted to an RF signal to be transmitted over the satellite antenna. Contact: Walt Magnussen Email: telecom@tamu.edu http://itec.tamu.edu

    11. Supporting Vendors to date • Agilent • Alcatel • Anritsu • Aparentnetworks • Broadsoft • Cisco • IPTel • IXIA • Nortel • Pingtel • Siemens • Shoreline

    12. TAMU ITEC

    13. For Additional Information Walt Magnussen Texas A&M University ITEC.TAMU.EDU Telecom@Tamu.edu 979-845-5588 The TAMU ITEC is proud to be working with ADEC !