7.2.5       AuditValue...........................................57       7.2.6       AuditCapabilities....................................60       7.2.7       Notify...............................................62       7.2.8       ServiceChange........................................63       7.2.9       Manipulating and Auditing Context Attributes.........68       7.2.10      Generic Command Syntax...............................69              8           TRANSACTIONS.........................................69       8.1         Common parameters....................................71       8.1.1       Transaction Identifiers..............................71       8.1.2       Context Identifiers..................................71       8.2         Transaction Application Programming Interface........71       8.2.1       TransactionRequest...................................72       8.2.2       TransactionReply.....................................72       8.2.3       TransactionPending...................................74       8.3         Messages.............................................75              9           TRANSPORT............................................75       9.1         Ordering of Commands.................................76       9.2         Protection against Restart Avalanche.................77              10          SECURITY CONSIDERATIONS..............................78       10.1        Protection of Protocol Connections...................79       10.2        Interim AH scheme....................................79       10.3        Protection of Media Connections......................80              11          MG-MGC CONTROL INTERFACE.............................81       11.1        Multiple Virtual MGs.................................81       11.2        Cold start...........................................82       11.3        Negotiation of protocol version......................82       11.4        Failure of a MG......................................83       11.5        Failure of an MGC....................................84              12          PACKAGE DEFINITION...................................85       12.1        Guidelines for defining packages.....................85       12.1.1      Package..............................................86            Groves et al            Expires - October 2003                [Page 4]                          Megaco Protocol version 2            April 2003               12.1.2      Properties...........................................87       12.1.3      Events...............................................88       12.1.4      Signals..............................................88       12.1.5      Statistics...........................................89       12.1.6      Procedures...........................................89       12.2        Guidelines to defining Parameters to Events and                       Signals..........................................89       12.3        Lists................................................90       12.4        Identifiers..........................................90       12.5        Package registration.................................91              13          PROFILE DEFINITION...................................91              14          IANA CONSIDERATIONS..................................92       14.1        Packages.............................................92       14.2        Error codes..........................................93       14.3        ServiceChange reasons................................93       14.4        Profiles.............................................94              ANNEX A     BINARY ENCODING OF THE PROTOCOL......................95       A.1         Coding of wildcards..................................95       A.2         ASN.1 syntax specification...........................96              ANNEX B     TEXT ENCODING OF THE PROTOCOL.......................120       B.1         Coding of wildcards.................................120       B.2         ABNF specification..................................120       B.4         Hexadecimal octet sequence..........................137              ANNEX C     TAGS FOR MEDIA STREAM PROPERTIES....................138       C.1         General media attributes............................138       C.2         Mux properties......................................140       C.3         General bearer properties...........................140       C.4         General ATM properties..............................141       C.5         Frame Relay.........................................145       C.6         IP 146       C.7         ATM AAL2............................................146       C.8         ATM AAL1............................................148       C.9         Bearer capabilities.................................150       C.10        AAL5 properties.....................................161       C.11        SDP equivalents.....................................162       C.12        H.245...............................................164              ANNEX D     TRANSPORT OVER IP...................................165       D.1         Transport over IP/UDP using Application Level Framing                      (ALF)............................................165       D.1.1       Providing At-Most-Once functionality................165       D.1.2       Transaction identifiers and three-way handshake.....166       D.1.2.1     Transaction identifiers.............................166       D.1.2.2     Three-way handshake.................................166            Groves et al            Expires - October 2003                [Page 5]                          Megaco Protocol version 2            April 2003               D.1.3       Computing retransmission timers.....................167       D.1.4       Provisional responses...............................168       D.1.5       Repeating Requests, Responses and Acknowledgements..168       D.2         Using TCP...........................................170       D.2.1       Providing the At-Most-Once functionality............170       D.2.2       Transaction identifiers and three-way handshake.....170       D.2.3       Computing retransmission timers.....................170       D.2.4       Provisional responses...............................171       D.2.5       Ordering of commands................................171              ANNEX E     BASIC PACKAGES......................................172       E.1         Generic.............................................172       E.2         Base Root Package...................................174       E.3         Tone Generator Package..............................178       E.4         Tone Detection Package..............................179       E.5         Basic DTMF Generator Package........................182       E.6         DTMF detection Package..............................184       E.7         Call Progress Tones Generator Package...............186       E.8         Call Progress Tones Detection Package...............187       E.9         Analog Line Supervision Package.....................188       E.10        Basic Continuity Package............................192       E.11        Network Package.....................................195       E.12        RTP Package.........................................197       E.13        TDM Circuit Package.................................199              APPENDIX I  Example Call Flows..................................201       I.1         Residential Gateway to Residential Gateway Call.....201       I.1.1       Programming Residential GW Analog Line Terminations                       for Idle Behaviour..............................201       I.1.2       Collecting Originator Digits and Initiating Termination                     .................................................203              APPENDIX II CHANGES FROM RFC XXXX [draft-ietf-megaco-3015corr                      -02.txt].........................................213              INTELLECTUAL PROPERTY RIGHTS....................................217       Acknowledgments.................................................218       Authors' Addresses..............................................219                          Groves et al            Expires - October 2003                [Page 6]                          Megaco Protocol version 2            April 2003            1  SCOPE       This document defines the protocols used between elements of a       physically decomposed multimedia gateway. There are no functional       differences from a system view between a decomposed gateway, with       distributed sub-components potentially on more than one physical       device, and a monolithic gateway such as described in Recommendation       H.246. This document does not define how gateways, multipoint control       units or interactive voice response units (IVRs) work. Instead it       creates a general framework that is suitable for these applications.       Packet network interfaces may include IP, ATM or possibly others. The       interfaces will support a variety of Switched Circuit Network (SCN)       signalling systems, including tone signalling, ISDN, ISUP, QSIG and       GSM. National variants of these signalling systems will be supported       where applicable.       Products claiming compliance with Version 1 of H.248.1 shall comply       with all of the mandatory requirements of H.248.1 originally approved       in 06/2000 and reissued in 03/2002.  H.248.1 (03/2002) is common text       with RFC xxxx [draft-ietf-megaco-3015corr-03.txt].       Products claiming compliance with Version 2 of H.248.1 shall comply       with all of the mandatory requirements of H.248.1 approved on       05/2002.  H.248.1 (05/2002) is common text with this document.       Products shall indicate the version of the protocol in use by using       ServiceChangeVersion as