Specifications for the Network Voice Protocol (NVP)
RFC 741

Document Type RFC - Unknown (November 1977; No errata)
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NWG/RFC 741                                           DC 22 Nov 77 42444

                         SPECIFICATIONS FOR THE
                      NETWORK VOICE PROTOCOL (NVP)

         Appendix 1:  The Definition of Tables-Set-#1 (for LPC)

              Appendix 2:  Implementation Recommendations

   NSC NOTE 68

   (Revision of NSC Notes 26, 40, and 43)

   Danny Cohen, ISI

   January 29, 1976

NWG/RFC 741                                           DC 22 Nov 77 42444
Specifications for the Network Voice Protocol (NVP)


   PREFACE                                                           iii

   ACKNOWLEDGMENTS                                                    iv

   INTRODUCTION                                                        2

   THE CONTROL PROTOCOL                                                2
      Summary of the CONTROL Messages                                  3
      Definition of the CONTROL Messages                               4
      Definition of the <WHAT> and <HOW>
         Negotiation Tables                                            8
      On RENEGOTIATION                                                10
      The Header of Data Messages                                     10

   THE LPC DATA PROTOCOL                                              13

   EXAMPLES FOR THE CONTROL PROTOCOL                                  15

   APPENDIX 1:  THE DEFINITION OF TABLES-SET-#1                       18
      General Comments                                                20
      Comments on the PITCH Table                                     20
      Comments on the GAIN Table                                      21
      Comments on the INDEX7 Table                                    21
      Comments on the INDEX6 Table                                    21
      Comments on the INDEX5 Table                                    21
      The PITCH Table                                                 22
      The GAIN Table                                                  24
      The INDEX7 Table                                                25
      The INDEX6 Table                                                26
      The INDEX5 Table                                                27


   REFERENCES                                                         30

Cohen                                                          [Page ii]

NWG/RFC 741                                           DC 22 Nov 77 42444
Specifications for the Network Voice Protocol (NVP)


   The major objective  of ARPA's  Network  Secure  Communications (NSC)
   project  is to develop  and demonstrate  the feasibility  of  secure,
   high-quality, low-bandwidth, real-time, full-duplex (two-way) digital
   voice communications  over  packet-switched  computer  communications
   networks.   This kind  of  communication  is  a  very  high  priority
   military  goal for all levels  of  command  and  control  activities.
   ARPA's  NSC projrct will supply digitized speech which can be secured
   by existing  encryption  devices.  The major goal of this research is
   to demonstrate  a digital  high-quality,  low-bandwidth, secure voice
   handling  capability  as part of the general military requirement for
   worldwide  secure voice communication.  The development at ISI of the
   Network  Voice Protocol  described herein is an important part of the
   total effort.

Cohen                                                         [Page iii]

NWG/RFC 741                                           DC 22 Nov 77 42444
Specifications for the Network Voice Protocol (NVP)


   The Network Voice Protocol (NVP), implemented first in December 1973,
   and has been in use since then for local and transnet real-time voice
   communication over the ARPANET at the following sites:

      o    Information  Sciences  Institute,  for LPC and CVSD,  with  a
           PDP-11/45 and an SPS-41.

      o    Lincoln  Laboratory,  for LPC and CVSD,  with a TX2  and  the
           Lincoln FDP, and with a PDP-11/45 and the LDVT.

      o    Culler-Harrison,  Inc.,  for LPC,  with  the  Culler-Harrison
           MP32A and AP-90.

      o    Stanford Research Institute, for LPC, with a PDP-11/40 and an

   The NVP's success  in bridging  the  differences  between  the  above
   systems  is due mainly  to the cooperation  of  many  people  in  the
   ARPA-NSC  community,  including Jim Forgie (Lincoln Laboratory), Mike
   McCammon  (Culler-Harrison),  Steve Casner  (ISI)  and Paul  Raveling
   (ISI),  who participated  heavily  in the definition  of the  control
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