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Internet Draft   RTP MIB                              August 7, 1998


                 Real-Time Transport Protocol
                 Management Information Base
               <draft-ietf-avt-rtp-mib-02.txt>

                        August 7, 1998

                         Mark Baugher
                       Intel Corporation
                      2111 N.E.25th Avenue
                    Hillsboro, Oregon  97124

                      mbaugher@intel.com


                            John Du
                       Intel Corporation
                      2111 N.E.25th Avenue
                    Hillsboro, Oregon  97124

                        John.Du@intel.com


                          Stan Naudus
                       3Com Corporation
                     2070 Chain Bridge Road
                     Vienna, Virginia  22182

                       Stan_Naudus@3Com.com


Status of this Memo

This document is an Internet-Draft.  Internet-Drafts are
working documents of the Internet Engineering Task Force
(IETF), its areas, and its working groups.  Note that other
groups may also distribute working documents as Internet-
Drafts.

Internet-Drafts are draft documents valid for a maximum of six
months.  Internet-Drafts may be updated, replaced, or made
obsolete by other documents at any time.  It is not
appropriate to use Internet-Drafts as reference material or to
cite them other than as a ``working draft'' or ``work in
progress.''

To learn the current status of any Internet-Draft, please
check the 1id-abstracts.txt listing contained in the Internet-
Drafts Shadow Directories on ds.internic.net, nic.nordu.net,
venera.isi.edu, or munnari.oz.au.



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1.  Changes from Previous Draft

There is a large change introduced in this draft from the
previous draft:  The tables for the RTP host and the
RTP monitor have been merged.  The rtpInTable and rtpEgTable
have been removed and their objects are subsumed by the
rtpRcvrTable and rtpSenderTable, respectively.  The rtpRRTable
and the rtpSRTable for RTP monitors are removed and their
objects are subsumed by the rtpRcvrTable and rtpSenderTable
respectively.  rtpSessionMonitor has been added to the
rtpSessionTable to distinguish between sessions that are
being sourced or received by the local RTP System and sessions
that are being monitored by a third-party monitor or by a
local RTP System that may also be sending or receiving
RTP Session data.

For clarity an explicit address pair, rtpSessionLocAddr
and rtpSessionRemAddr have been added to the rtpSessionTable
to identify an RTP Session and replace the rtpEgDstAddr and
rtpInDstAddr objects.  rtpSessionRemAddr replaces (renames)
rtpSessionAddr.  Finally, rtpRRFracLost has been removed as an
object used by RTP monitors in favor of polling and computing
loss statistics in the network management application.

2.  Abstract

This memo defines an experimental  Management Information Base
(MIB) for use with network management protocols in
TCP/IP-based internets.  In particular, it defines objects for
managing Real-Time Transport Protocol systems [1].  Comments
should be made to the IETF Audio/Video Transport Working Group
at rem-conf@es.net.

This memo does not specify a standard for the Internet
community.


3.  The Network Management Framework

The SNMPv2 Network Management Framework consists of the
following major components:








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RFC 1902 which defines the SMI, the mechanisms used for
describing and naming objects for the purpose of management.

RFC 1903 Textual Conventions for Version 2 of the Simple
Network Management Protocol (SNMPv2).

RFC 1904 Conformance Statements for Version 2 of the
Simple Network Management Protocol (SNMPv2).

RFC 1905 Protocol Operations for Version 2 of the
Simple Network Management Protocol (SNMPv2).

RFC 1906 Transport Mappings for Version 2 of the
Simple Network Management Protocol (SNMPv2).

RFC 1907 Management Information Base for Version 2 of
the Simple Network Management Protocol (SNMPv2).

RFC 1908 Coexistence between Version 1 and Version 2 of
the Internet-standard Network Management Framework.

The Framework permits new objects to be defined for the
purpose of experimentation and evaluation.

Managed objects are accessed via a virtual information store,
termed the Management Information Base or MIB.  Within a given
MIB module, objects are defined using the SMI's OBJECT-TYPE
macro[2].  At a minimum, each object has a name, a syntax, an
access-level, and an implementation-status.

The name is an object identifier, an administratively assigned
name, which specifies an object type.  The object type
together with an object instance serves to uniquely identify a
specific instantiation of the object.  For human convenience,
we often use a textual string, termed the object descriptor,
to also refer to the object type.

The syntax of an object type defines the abstract data
structure corresponding to that object type.  The ASN.1[3]
language is used for this purpose.  However, RFC 1902
purposely restricts the ASN.1 constructs which may be used.
These restrictions are made for simplicity.

The access-level of an object type defines whether it makes
"protocol sense" to read and/or write the value of an instance
of the object type.  (This access-level is independent of any
administrative authorization policy.)

The implementation-status of an object type indicates whether
the object is mandatory, optional, obsolete, or deprecated.

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4. Overview

An "RTP System" may be a host end-system that runs an application
program that sends or receives RTP data packets, or it may be an
intermediate-system that forwards RTP packets.  RTP Control
Protocol (RTCP) packets are sent by senders and receivers to
convey information about RTP packet transmission and reception [1].
RTP monitors may collect RTCP information on senders and receivers
to and from an RTP host or intermediate-system.

4.1 Components

The RTP MIB is structured around "Session," "Receiver" and "Sender"
conceptual abstractions.

4.1.1  An "RTP Session" is the "...association of participants
communicating with RTP.  For each participant, the session is
defined by a particular pair of destination transport addresses
(one network address plus a port pair for RTP and RTCP).  The
destination transport addresses may be common for all participants,
as in the case of IP multicast, or may be different for each, as in
the case of individual unicast addresses plus a common port pair,"
as defined in section 3 of [1].

4.1.2 A "Sender" is identified within an RTP Session by a 32-bit numeric
"Synchronization Source," or "SSRC", value and is "...the source of a
stream of RTP packets" as defined in section 3 of [1].  The Sender is
also a source of RTCP Sender Report packets as specified in section 6
of [1].

4.1.3 A "Receiver" of a "stream of RTP packets" can be a unicast or
multicast Receiver as described in 4.2.1, above. An RTP Receiver has
an SSRC value that is unique to the session.  An RTP Receiver is a
source of RTCP Receiver Reports as specified in section 6 of [1].

4.2 Textual Conventions

A new data type, InterfaceIndex, is introduced as a textual convention
in this MIB document.  Textual conventions enhance the readability of
the specification and can ease comparison with other specifications
if appropriate.  It should be noted that the introduction of the
textual conventions has no effect on either the syntax nor the
semantics of any managed objects.  The use of these is merely an
artifact of the explanatory method used.  Objects defined in terms of
one of these methods are always encoded by means of the rules that
define the primitive type.  Hence, no changes to the SMI or the SNMP
are necessary to accommodate these textual conventions which are
adopted merely for the convenience of readers and writers.




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4.3 Applicability of the MIB to RTP System Implementations

The RTP MIB may be used in two types of RTP implementations, RTP Host
Systems (end systems)  and RTP Monitors, see section 3 of [1].
Use of the RTP MIB for RTP Translators and Mixers, as defined in
section 7 of [1], is for further study.

4.3.1 RTP Host Systems are end-systems that may use the RTP MIB
to collect RTP Session and Stream data that the host is sending or
receiving; these data may be used by a network manager to detect and
diagnose faults that occur over the life time of an RTP Session as
in a "help-desk" scenario.

4.3.2 RTP Monitors of multicast RTP sessions may be third-party, or
may be located in an RTP intermediate-system or in the host.  RTP
Monitors may use the RTP MIB to collect RTP Session and Stream
statistical data; these data may be used by a network manager for
capacity planning and other network-management purposes.  An RTP
Monitor may use the RTP MIB to collect data to permit a network
manager to detect and diagnose faults in RTP sessions, or to permit
a network manger to configure its operation.

4.4  The Structure of the RTP MIB

There are three tables in the RTP MIB.  The rtpSessionTable contains
objects that describe active sessions at the host, intermediate system,
or monitor.  The rtpSenderTable contains information about senders
to the RTP Session.  The rtpRcvrTable contains information about
receivers of RTP Session data.

For any particular RTP Session, the rtpSessionMonitor object indicates
whether information about remote senders or receivers to the RTP
Session are to be monitored.  RTP Sessions are monitored by the
sub-agent that updates rtpSenderTable and rtpRcvrTable objects with
information from RTCP reports from remote senders or remote receivers
respectively.

rtpSessionNewIndex is a global object that permits a network-management
application to obtain a unique index for conceptual row creation
in the rtpSessionTable.  In this way the SNMP Set operation may
be used to configure a monitor.










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4.5  SNMP Implementations

An RTP System that runs either a single application or multiple
applications with a single management-entity may be a practical
configuration for monitoring, translating or mixing.  Host end-
-systems are the vast majority of RTP implementations, however,
a "monolithic" solution may be inadequate if management of
RTP end-systems proves to be truly useful.  The RTP MIB contains
tables that may be shared among RTP application programs that run
concurrently on the same device - as many or most do.  Sharing
occurs on a table basis.

Table sharing may be a problem for SNMP management entities on some
host operting systems:  All SNMP management requests are sent to UDP
Port 161, and an Application Programming Interface (API) is needed to
facilitate this sharing.  The API is specific to the host operating
system, and there are solutions provided by host operating system
vendors and by independent software vendors.  There is also a
standardization effort within the IETF to at least define a standard
system-interface protocol that may be implemented in an API to permit
multiple management entities to share the object name space[4].  Whether
or not independent RTP application programs can cooperatively and
concurrently support the RTP MIB is outside the scope of this draft
document and will depend upon the operating system in question.



























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5. Definitions

RTP DEFINITIONS ::= BEGIN
IMPORTS
       Counter32, Gauge32, experimental, Integer32,
       IpAddress, MODULE-IDENTITY, OBJECT-IDENTITY,
       OBJECT-TYPE, Unsigned32                     FROM SNMPv2-SMI
       DisplayString, RowStatus, TAddress,
       TDomain, TestAndIncr, TEXTUAL-CONVENTION,
       TimeStamp, TruthValue                       FROM SNMPv2-TC
       OBJECT-GROUP, MODULE-COMPLIANCE             FROM SNMPv2-CONF;

rtp     MODULE-IDENTITY
       LAST-UPDATED "9807212000Z"
       ORGANIZATION "IETF AVT Working Group"
       CONTACT-INFO
              "Mark Baugher
       Postal: Intel Corporation
              2111 NE 25th Avenue
              Hillsboro, OR   97124
              United States
       Tel:    +1 503 264 3849
       Email:  mbaugher@intel.com

               John Du
       Postal: Intel Corporation
              2111 NE 25th Avenue
              Hillsboro, OR   97124
              United States
       Tel:    +1 503 264 0636
       Email:  John.Du@intel.com

              Stan Naudus
       Postal: 3Com Corporation
              2070 Chain Bridge Road
              Vienna, VA
              United States
       Tel:    +1 703 848 7710
       Email:  Stan_Naudus@3Com.com"
        DESCRIPTION
       "The managed objects of RTP systems.  The MIB is
        structured around three types of information.
        1. General information about RTP Sessions such
           as the Session Address.
        2. Information about RTP streams being sent to
           an RTP Session by a particular source.
        3. Information about RTP streams received on an
           RTP Session by a particular receiver from a
            particular sender.


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         There are two types of RTP Systems, RTP hosts and
         RTP monitors.  As described below, certain objects
         are unique to a particular type of RTP System.   An
         RTP host may also function as an RTP monitor.
         Refer to RFC 1889, 'RTP: A Transport Protocol for
         Real-Time Applications,' section 3.0, for definitions."
::= { experimental 77 }


InterfaceIndex ::= TEXTUAL-CONVENTION
    STATUS      current
    DESCRIPTION
       "The range of ifIndex.  This is defined here since zero
       is used to define an unnumbered interface."
    SYNTAX      Integer32

--
-- OBJECTS
--
rtpGlobals OBJECT IDENTIFIER ::= { rtp 1 }

rtpDomains OBJECT IDENTIFIER ::= { rtpGlobals 1 }

rtpUDPDomain OBJECT-IDENTITY
       STATUS          current
       DESCRIPTION
          "RTP over UDP transport domain over IPv4.  This definition
          uses the transport address type, snmpUDPAddress, which is
          defined in SNMPv2-TM, 'Transport Mappings for Version 2 of
          the Simple Network Management Protocol (SNMPv2)'."
       REFERENCE       "RFC 1906, sec. 2 "
       ::= { rtpDomains 1 }



















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--
--  SESSION TABLE
--
rtpSessionNewIndex OBJECT-TYPE
       SYNTAX          TestAndIncr
       MAX-ACCESS      read-write
       STATUS          current
       DESCRIPTION
          "This  object  is  used  to  assign  values  to
          rtpSessionIndex  as described in 'Textual
          Conventions  for  SNMPv2'.  For an RTP monitor
          system, the  network  manager would read
          the  object,  and  then write the value back in
          the Set that creates a new instance  of
          rtpSessionEntry.   If  the  Set  fails with the code
          'inconsistentValue,' then the process must be
          repeated; If the Set succeeds, then the object
          is incremented, and the  new  instance  is
          created according to the manager's directions.
          However, if the RTP system is not a monitor, only
          the RTP sub-agent may create conceptual rows in the
          RTP session table."
       ::= { rtpGlobals 2 }

rtpSessionTable OBJECT-TYPE
       SYNTAX          SEQUENCE OF RtpSessionEntry
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "There's one entry in the SessionTable for each RTP Session
          on which packets are being sent, received, and/or
          monitored."
       ::= { rtp 2 }



















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rtpSessionEntry OBJECT-TYPE
       SYNTAX          RtpSessionEntry
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "Data in rtpSessionTable uniquely identify an RTP
          Session.  A host sub-agent will create a read-only row for
          each session to which packets are being sent or received.
          An RTP Session can be monitored to create management
          information on all RTP streams being sent or received when
          the rtpSessionMonitor has the TruthValue of 'true(1)'.  A
          monitor sub-agent may permit row creation with the side
          effect of causing the RTP System to join the session for
          the purposes of gathering management information (thus
          additional conceptual rows are created in the rtpRcvrTable
          and rtpSenderTable).  rtpSessionTable rows can be created for
          RTP Session monitoring purposes.  Rows created by a
          management application may be deleted via SNMP operations."
       INDEX { rtpSessionIndex  }
       ::= { rtpSessionTable 1 }

RtpSessionEntry ::= SEQUENCE {
       rtpSessionIndex         Integer32,
       rtpSessionDomain        TDomain,
       rtpSessionRemAddr       TAddress,
       rtpSessionLocAddr       TAddress,
       rtpSessionIfIndex       InterfaceIndex,
       rtpSessionIfAddr        IpAddress,
       rtpSessionSenders       Counter32,
       rtpSessionReceivers     Counter32,
       rtpSessionByes          Counter32,
       rtpSessionStartTime     TimeStamp,
       rtpSessionMonitor       TruthValue,
       rtpSessionRowStatus     RowStatus
       }

rtpSessionIndex OBJECT-TYPE
       SYNTAX          Integer32 (1..65535)
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "The index of the conceptual row which is for SNMP purposes
           only and has no relation to any protocol value."
       ::= { rtpSessionEntry 1}








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rtpSessionDomain OBJECT-TYPE
       SYNTAX          TDomain
       MAX-ACCESS      read-create
       STATUS          current
       DESCRIPTION
          "The transport-layer protocol used for sending or receiving
           the stream of RTP data packets on this session.
           Cannot be changed after rtpSessionRowStatus is 'active'."
       DEFVAL { rtpUDPDomain }
       ::= { rtpSessionEntry 2 }

rtpSessionRemAddr OBJECT-TYPE
       SYNTAX          TAddress
       MAX-ACCESS      read-create
       STATUS          current
       DESCRIPTION
          "The remote destination transport address on which the stream
          of RTP data packets is being sent and/or received.  An RTP
          Session is defined by a pair of destination transport
          addresses.  'The destination address pair may be common for
          all participants, as in the case of IP multicast, or may be
          different for each, as in the case of individual unicast
          network address pairs.'  See RFC 1889, 'RTP: A Transport
          Protocol for Real-Time Applications, sec. 3.  The transport
          service is identified by rtpSessionDomain.  For rtpUDPDomain,
          this is an IP address and an even-numbered UDP Port with the
          RTCP being sent on the next higher odd-numbered port, see
          RFC 1889, sec. 5. Cannot be changed after rtpSessionRowStatus
          is 'active'."
       ::= { rtpSessionEntry 3 }

rtpSessionLocAddr OBJECT-TYPE
       SYNTAX          TAddress
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The local destination transport address on which the stream
          of data packets is being sent and/or received.  For unicast
          RTP Sessions, this is the local address of the
          RTP Session.  For IP multicast RTP Sessions, this object should
          have the same value as rtpSessionRemoteAddr.  See RFC 1889,
          'RTP: A Transport Protocol for Real-Time Applications, sec.
          3.  The transport service is identified by rtpSessionDomain.
          For rtpUDPDomain, this is an IP address and an even-numbered
          UDP Port with the RTCP being sent on the next higher
          odd-numbered port, see RFC 1889, sec. 5."
       ::= { rtpSessionEntry 4 }





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rtpSessionIfIndex OBJECT-TYPE
       SYNTAX          InterfaceIndex
       MAX-ACCESS      read-create
       STATUS          current
       DESCRIPTION
          "The ifIndex value is zero for interfaces that have an IP
          address defined for the interface on which RTP data packets
          are sent or received for this session. Otherwise this object
          is set to the corresponding value from the Internet Standard
          MIB.  Cannot be changed after rtpSessionRowStatus is
          'active'.  A zero value for both rtpSessionIfIndex and
          rtpSessionIfAddr indicates that the default interface be
          used."
         DEFVAL { 0 }
       ::= { rtpSessionEntry 5 }

rtpSessionIfAddr OBJECT-TYPE
       SYNTAX          IpAddress
       MAX-ACCESS      read-create
       STATUS          current
       DESCRIPTION
         "The IP Address of the interface on which the stream of RTP
         data packets is being sent and/or received for interfaces that
         have an IP Address.  If rtpSessionIfIndex is non-zero, this
         object should have the value 0.0.0.0.  Cannot be changed after
         rtpSessionRowStatus has become 'active'.  A zero
         value for both rtpSessionIfIndex and rtpSessionIfAddr
         indicates that the default interface be used."
         DEFVAL { 0 }
       ::= { rtpSessionEntry 6 }

rtpSessionSenders OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The maximum number of senders observed by
          the monitor since this conceptual row was created
          (rtpSessionStartTime).  Senders that leave and then
          re-join following an RTCP BYE (See RFC 1889, 'RTP: A
          Transport Protocol for Real-Time Applications,' sec. 6.6)
          or session timeout may be counted twice."
       ::= { rtpSessionEntry 7 }









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rtpSessionReceivers OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The maximum number of receivers that are
          observed since this conceptual row was created
          (rtpSessionStartTime).  Receivers that leave and then re-join
          following an RTCP BYE (See RFC 1889, 'RTP: A Transport
          Protocol for Real-Time Applications,' sec. 6.6)or session
          timeout may be counted twice."
       ::= { rtpSessionEntry 8 }


rtpSessionByes OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "A count of RTCP BYE (See RFC 1889, 'RTP: A Transport
           Protocol for Real-Time Applications,' sec. 6.6) messages
           received by this entity."
       ::= { rtpSessionEntry 9 }

rtpSessionStartTime OBJECT-TYPE
       SYNTAX          TimeStamp
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The value of SysUpTime at the time that this row was
          created."
       ::= { rtpSessionEntry 10 }

rtpSessionMonitor OBJECT-TYPE
       SYNTAX          TruthValue
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Boolean, Set to 'true(1)' if senders or receivers in addition
          to the local RTP System are to be monitored.  RTP Host Systems
          MUST initialize this to 'false(2)'.  RTP Monitors MUST
          initialize to 'true(1)' and RTP Hosts MUST initialize this
          'false(2)'."
       ::= { rtpSessionEntry 11 }








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rtpSessionRowStatus OBJECT-TYPE
       SYNTAX          RowStatus
       MAX-ACCESS      read-create
       STATUS          current
       DESCRIPTION
          "Value of 'active' when RTP or RTCP messages being sent or
          received by an RTP System are being monitored.  A manager-
          created conceptual row must have the rtpSessionAddr initialized
          by the manager before becoming 'active' A conceptual row that
          is in the 'notReady' or 'notInService' state MAY be
          removed after 5  minutes."
       ::= { rtpSessionEntry 12 }

--
--  SENDERS TABLE
--
rtpSenderTable OBJECT-TYPE
       SYNTAX          SEQUENCE OF RtpSenderEntry
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "Table of information about a sender or senders to an RTP
          Session. Sub-agents for RTP sending hosts MUST create an
          entry in this table for each stream being sent.  Sub-agents
          for RTP monitors create an entry for each observed RTP Session
          sender as a side-effect when a conceptual row in the
          rtpSessionTable is made 'active' by a manager."
       ::= { rtp 3 }

rtpSenderEntry OBJECT-TYPE
       SYNTAX          RtpSenderEntry
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "Each entry contains monitoring information from a single RTP
          Synchronization Source (SSRC, see RFC 1889 'RTP: A Transport
           Protocol for Real-Time Applications' sec.6).  The session is
           identified to the the SNMP entity by rtpSessionIndex."
       INDEX { rtpSessionIndex, rtpSenderSSRC }
       ::= { rtpSenderTable 1 }












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RtpSenderEntry ::= SEQUENCE {
       rtpSenderSSRC           Unsigned32,
       rtpSenderCNAME          DisplayString,
       rtpSenderAddr           TAddress,
       rtpSenderPackets        Counter32,
       rtpSenderOctets         Counter32,
       rtpSenderTool           DisplayString,
       rtpSenderSRs            Counter32,
       rtpSenderSRTime         TimeStamp,
       rtpSenderPT             INTEGER,
       rtpSenderStartTime      TimeStamp
       }

rtpSenderSSRC OBJECT-TYPE
       SYNTAX          Unsigned32
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "The RTP SSRC, or synchronization source identifier of the
          sender.  The RTP Session Address plus an SSRC uniquely
          identify a sender or receiver of an RTP stream (see RFC 1889,
          'RTP: A Transport Protocol for Real-Time Applications'
          sec.3)."
       ::= { rtpSenderEntry 1 }

rtpSenderCNAME OBJECT-TYPE
       SYNTAX          DisplayString (SIZE(0..255))
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
         "The RTP canonical name of the sender."
       ::= { rtpSenderEntry 2 }

rtpSenderAddr OBJECT-TYPE
       SYNTAX          TAddress
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The unicast transport source address of the sender."
       ::= { rtpSenderEntry 3 }

rtpSenderPackets OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Count of RTP packets sent by this sender, or observed by
          an RTP monitor from RTCP Reports, since rtpSenderStartTime."
       ::= { rtpSenderEntry 4 }



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rtpSenderOctets OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Count of RTP octets sent by this sender, or observed by
          an RTP monitor from RTCP Reports, since rtpSenderStartTime."
       ::= { rtpSenderEntry 5 }

rtpSenderTool OBJECT-TYPE
       SYNTAX          DisplayString (SIZE(0..127))
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Name of the application program that's the stream source."
       DEFVAL { ''H }  -- Null if not available
       ::= { rtpSenderEntry 6 }

rtpSenderSRs OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "A count of the number of RTCP Sender Reports that have
          been sent from this sender, or observed if the RTP entity
          is a monitor, since rtpSenderStartTime."
       ::= { rtpSenderEntry 7 }

rtpSenderSRTime OBJECT-TYPE
       SYNTAX          TimeStamp
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The value is always zero if the source of the RTP Stream is
          the local RTP System.  Otherwise, rtpSenderSRTime is the
          value of SysUpTime at the time that the last SR was received
          from this sender, in the case of a monitor."
       ::= { rtpSenderEntry 8 }

rtpSenderPT OBJECT-TYPE
       SYNTAX          INTEGER (0..127)
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Static or dynamic payload type from the RTP header (see RFC
           1889, 'RTP: A Transport Protocol for Real-Time Applications'
           sec. 5)."
       ::= { rtpSenderEntry 9 }



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rtpSenderStartTime OBJECT-TYPE
       SYNTAX          TimeStamp
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The value of SysUpTime at the time that this row was
          created."
       ::= { rtpSenderEntry 10 }

--
--  RECEIVERS TABLE
--
rtpRcvrTable OBJECT-TYPE
       SYNTAX          SEQUENCE OF RtpRcvrEntry
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "Table of information about a receiver or receivers of RTP
           Session data. Sub-agents for RTP hosts that receive RTP
           Session packets create an entry in this table for that
           receiver/sender pair Sub-agents for RTP monitors create an
           entry for each observed RTP Session receiver as a side-
           effect when a conceptual row in the rtpSessionTable is made
           'active' by a manager."
       ::= { rtp 4 }

rtpRcvrEntry OBJECT-TYPE
       SYNTAX          RtpRcvrEntry
       MAX-ACCESS      not-accessible
       STATUS          current
       DESCRIPTION
          "Each entry contains monitoring information from a single RTP
           Synchronization Source (SSRC, see RFC 1889, 'RTP: A Transport
           Protocol for Real-Time Applications' sec.6).  The session is
           identified to the the SNMP entity by rtpSessionIndex."
       INDEX { rtpSessionIndex, rtpRcvrRemSSRC, rtpRcvrLocSSRC }
       ::= { rtpRcvrTable 1 }














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RtpRcvrEntry ::= SEQUENCE {
       rtpRcvrRemSSRC        Unsigned32,
       rtpRcvrLocSSRC        Unsigned32,
       rtpRcvrCNAME          DisplayString,
       rtpRcvrAddr           TAddress,
       rtpRcvrRTT            Gauge32,
       rtpRcvrLostPackets    Counter32,
       rtpRcvrLostOctets     Counter32,
       rtpRcvrJitter         Gauge32,
       rtpRcvrTool           DisplayString,
       rtpRcvrRRs            Counter32,
       rtpRcvrRRTime         TimeStamp,
       rtpRcvrPT             INTEGER,
       rtpRcvrPackets        Counter32,
       rtpRcvrOctets         Counter32,
       rtpRcvrStartTime      TimeStamp
       }

rtpRcvrRemSSRC OBJECT-TYPE
       SYNTAX       Unsigned32
       MAX-ACCESS   not-accessible
       STATUS       current
       DESCRIPTION
          "The RTP SSRC, or synchronization source identifier of the
          sender.  The RTP Session Address plus an SSRC uniquely
          identify a sender or receiver of an RTP stream (see RFC
          1889, 'RTP:  A Transport Protocol for Real-Time
          Applications' sec.3)."
       ::= { rtpRcvrEntry 1 }

rtpRcvrLocSSRC OBJECT-TYPE
       SYNTAX       Unsigned32
       MAX-ACCESS   not-accessible
       STATUS       current
       DESCRIPTION
          "The RTP SSRC, or synchronization source identifier of the.
          receiver.  The RTP Session Address plus an SSRC uniquely
          identify a sender or receiver of an RTP stream (see RFC
          1889, 'RTP:  A Transport Protocol for Real-Time
          Applications' sec.3)."
       ::= { rtpRcvrEntry 2 }

rtpRcvrCNAME OBJECT-TYPE
       SYNTAX       DisplayString (SIZE(0..255))
       MAX-ACCESS   read-only
       STATUS       current
       DESCRIPTION
          "The RTP canonical name of the receiver."
       ::= { rtpRcvrEntry 3 }



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rtpRcvrAddr OBJECT-TYPE
       SYNTAX       TAddress
       MAX-ACCESS   read-only
       STATUS       current
       DESCRIPTION
          "The unicast transport address of the receiver."
       ::= { rtpRcvrEntry 4 }

rtpRcvrRTT OBJECT-TYPE
       SYNTAX       Gauge32
       MAX-ACCESS   read-only
       STATUS       current
       DESCRIPTION
          "The round trip time measurement taken by the source of the
          RTP stream based on the algorithm described on sec. 6 of
          RFC 1889, 'RTP: A Transport Protocol for Real-Time
          Applications.'  This algorithm can produce meaningful
          results when the sub-agent has the same clock as the stream
          sender (when the RTP monitor is also a sending host for the
          particular reciever).  Otherwise, the entity should return
          'noSuchObject' in response to queries against rtpRcvrRTT."
       ::= { rtpRcvrEntry 5 }

rtpRcvrLostPackets OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "A count of RTP  packets lost as observed by this receiver
           since rtpRcvrStartTime."
       ::= { rtpRcvrEntry 6 }


rtpRcvrLostOctets OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "A count of RTP octets lost as observed by this receiver
           since rtpRcvrStartTime."
       ::= { rtpRcvrEntry 7 }

rtpRcvrJitter OBJECT-TYPE
       SYNTAX          Gauge32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "An estimate of delay variation as observed by this receiver."
       ::= { rtpRcvrEntry 8 }


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rtpRcvrTool OBJECT-TYPE
       SYNTAX          DisplayString (SIZE(0..127))
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Name of the application program that's receiving the stream."
       DEFVAL { ''H }  -- Null if not available
       ::= { rtpRcvrEntry 9 }

rtpRcvrRRs OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "A count of Receiver Reports as observed by this receiver
           since rtpSessionStartTime."
       ::= { rtpRcvrEntry 10 }

rtpRcvrRRTime OBJECT-TYPE
       SYNTAX         TimeStamp
       MAX-ACCESS     read-only
       STATUS         current
       DESCRIPTION
          "The value is always zero if the receiver of the RTP Stream
          is the local RTP System.  Otherwise, rtpRcvrRRTime is the
          value of SysUpTime at the time that the last RTCP Receiver
          Report was received from this receiver, in the case of a
          monitor, or sent by this receiver, in the case of a receiving
          host."
       ::= { rtpRcvrEntry 11 }

rtpRcvrPT OBJECT-TYPE
       SYNTAX          INTEGER (0..127)
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Static or dynamic payload type from the RTP header (see RFC
           1889, 'RTP: A Transport Protocol for Real-Time Applications'
           sec. 5)."
       ::= { rtpRcvrEntry 12 }











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rtpRcvrPackets OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Count of RTP packets received by this RTP host receiver since
           rtpRcvrStartTime. RTP Sessions being monitored ('true(1)'
           value for rtpSessionMonitor) may not have this information."
       ::= { rtpRcvrEntry 13 }


rtpRcvrOctets OBJECT-TYPE
       SYNTAX          Counter32
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "Count of RTP octets received by this receiving RTP host
           since rtpRcvrStartTime.  Monitored sessions (rtpSessionMonitor
           is 'false') may not have this information."
       ::= { rtpRcvrEntry 14 }

rtpRcvrStartTime OBJECT-TYPE
       SYNTAX          TimeStamp
       MAX-ACCESS      read-only
       STATUS          current
       DESCRIPTION
          "The value of SysUpTime at the time that this row was
          created."
       ::= { rtpRcvrEntry 15 }

--
--  MODULE GROUPS
--



















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rtpSystemGroup      OBJECT-GROUP
       OBJECTS          {
                       rtpSessionDomain,
                       rtpSessionRemAddr,
                       rtpSessionIfIndex,
                       rtpSessionIfAddr,
                       rtpSessionSenders,
                       rtpSessionReceivers,
                       rtpSessionStartTime,
                       rtpSessionRowStatus,
                       rtpSessionByes,
                       rtpSessionMonitor,
                       rtpSenderCNAME,
                       rtpSenderAddr,
                       rtpSenderPackets,
                       rtpSenderOctets,
                       rtpSenderTool,
                       rtpSenderSRs,
                       rtpSenderSRTime,
                       rtpSenderStartTime,
                       rtpRcvrCNAME,
                       rtpRcvrAddr,
                       rtpRcvrLostPackets,
                       rtpRcvrJitter,
                       rtpRcvrTool,
                       rtpRcvrRRs,
                       rtpRcvrRRTime,
                       rtpRcvrStartTime
                       }
       STATUS           current
       DESCRIPTION
               "Objects used by all RTP systems."
       ::= { rtp 5 }

rtpHostGroup      OBJECT-GROUP
       OBJECTS          {
                       rtpSessionLocAddr,
                       rtpSenderPT,
                       rtpRcvrPT,
                       rtpRcvrRTT,
                       rtpRcvrLostOctets,
                       rtpRcvrOctets,
                       rtpRcvrPackets
                       }
       STATUS           current
       DESCRIPTION
               "Objects used by RTP host systems."
       ::= { rtp 6 }




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rtpMonitorGroup  OBJECT-GROUP
       OBJECTS          {
                       rtpSessionNewIndex
                        }
       STATUS          current
       DESCRIPTION
               "Objects used by RTP monitor systems."
       ::= { rtp 7 }


rtpCompliance MODULE-COMPLIANCE
       STATUS          current
       DESCRIPTION
          "The management information of the objects in the
          rtpISGroup is taken from the IP, UDP, RTP headers
          and the required RTCP messages that are specified
          in RFC 1889, 'RTP: A Transport Protocol for Real-Time
          Applications', 6.4.  rtpRcvrTool and rtpSenderTool are
          not required fields in the RTCP SDES message so
          a DEFVAL is provided for these objects."
       MODULE           RTP
          MANDATORY-GROUPS { rtpSystemGroup }
          GROUP  rtpHostGroup
             DESCRIPTION
               "The objects in the rtpHostGroup MUST be
               implemented in RTP Host systems that are the source
               or the destination of RTP data packets."
          GROUP  rtpMonitorGroup
             DESCRIPTION
               "The objects in the rtpMonitorGroup MUST be
               implemented in RTP monitors."
          OBJECT  rtpSessionNewIndex
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP host system implementations MAY NOT support
                  row creation and deletion."
          OBJECT  rtpSessionDomain
             MIN-ACCESS read-only
              DESCRIPTION
                 "RTP host system implementations MAY NOT support
                  row creation and deletion."
          OBJECT  rtpSessionRemAddr
             MIN-ACCESS read-only
              DESCRIPTION
                 "RTP host system implementations MAY NOT support
                  row creation and deletion."





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          OBJECT  rtpSessionIfIndex
             MIN-ACCESS read-only
              DESCRIPTION
                 "RTP host system implementations MAY NOT support
                  row creation and deletion."
          OBJECT  rtpSessionIfAddr
             MIN-ACCESS read-only
              DESCRIPTION
                 "RTP host system implementations MAY NOT support
                  row creation and deletion."
          OBJECT  rtpSessionRowStatus
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP host system implementations MAY NOT support
                  row creation and deletion."
          OBJECT  rtpSessionLocAddr
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP monitor system implementations MAY NOT source
                 RTP or RTCP data packets."
          OBJECT  rtpRcvrPT
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP monitor system implementations MAY NOT support
                  retrieval of the RTP Payload Type from the RTP
                  header (and may receive RTCP messages only).  When
                  queried for the payload type information, the
                  sub-agent MAY return 'noSuchObject'."
          OBJECT  rtpSenderPT
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP monitor system implementations MAY NOT support
                  retrieval of the RTP Payload Type from the RTP
                  header (and may receive RTCP messages only).  When
                  queried for the payload type information, the
                  sub-agent MAY return 'noSuchObject'."
          OBJECT  rtpRcvrRTT
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "The round-trip time calculation presented
                 on sec. 6 of RFC 1889, 'RTP: A Transport
                 Protocol for Real-Time Applications',  may
                 be accurately computed by a monitor that uses
                 the same clock as a particular sender.  In other
                 cases, the monitor SHOULD return 'noSuchObject'
                 in response to a Get that references rtpRcvrRTT."





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          OBJECT  rtpRcvrLostOctets
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP monitor system implementations MAY NOT support
                 monitoring of this object when rtpSessionMonitor is
                 'true' since it is not obtainable from RTCP reports."
          OBJECT  rtpRcvrOctets
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP monitor system implementations MAY NOT support
                 monitoring of this object when rtpSessionMonitor is
                 'true' since it is not obtainable from RTCP reports."
          OBJECT  rtpRcvrPackets
             MIN-ACCESS not-accessible
              DESCRIPTION
                 "RTP monitor system implementations MAY NOT support
                 monitoring of this object when rtpSessionMonitor is
                 'true' since it is not obtainable from RTCP reports."
       ::= { rtp 8 }
END








6.  Security Issues

In most cases, MIBs are not themselves security risks; if SNMP security
is operating as intended, the use of a MIB to view information about a
system, or to change some parameter at the system, is a tool, not a
threat.

None of the read-only objects in this MIB reports a password, though
some SDES items such as the CNAME, the canonical name, may be deemed
sensitive depending on the security policies of a particular
enterprise.  If access to these objects is not limited by an
appropriate access control policy, these objects can provide an











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attacker with information about a system's configuration and the
services that that system is providing.  Some enterprises view their
network and system configurations themselves, as well as information
about usage and performance, as corporate assets; such enterprises may
wish to restrict SNMP access to most of the objects in the MIB.

This MIB supports read-write operations against rtpSessionNewIndex which
has the side effect of creating an entry in the rtpSessionTable when it
is written to.  Five objects in rtpSessionEntry have read-create access:
rtpSessionDomain, rtpSessionRemAddr, rtpSessionIfIndex,
rtpSessionRowStatus rtpSessionIfAddr identify an RTP Session to be
monitored on a particular interface.  The values of these objects are
not to be changed once created, and initialization of these objects
affects only the monitoring of an RTP Session and not the operation of
an RTP Session on any host end-system.  Since write operations to
rtpSessionNewIndex and the five objects in rtpSessionEntry affect the
operation of the monitor, write access to these objects should be
subject to the appropriate access control policy.

Confidentiality of RTP and RTCP data packets is defined in section 9 of
the RTP specification [1].  Encryption may be performed on RTP packets,
RTCP packets, or both.  Encryption of RTCP packets may pose a problem
for third-party monitors though "For RTCP, it is allowed to split a
compound RTCP packet into two lower-layer packets, one to be encrypted
and one to be sent in the clear.  For example, SDES information might
be encrypted while reception reports were sent in the clear to
accommodate third-party monitors [1]."
























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7.  Acknowledgements

George Kajos and Irina Suconick from Videoserver recommended some
changes in the structure and organization of the RTP MIB that are
contained in this draft.  Boris Bekkerman from 3Com identified
some problems in clarity and consistency of RTP MIB definitions.
Alan Batie and Bill Strahm from Intel have prototyped SNMP RTP
Monitors on FreeBSD and Windows NT, respectively.  The Windows
implementation is being used at Intel.  Bill Lewis from Intel
has written an RTP management application that is available in
binary form with the FreeBSD version of the SNMP RTP Monitor.


9.  References

[1]  H. Shulzrinne, S. Casner, R. Frederick, and V. Jacobson, "RTP:
     A Transport Protocol for real-time applications," RFC 1889.

[2]  J. Case, K. McCloghrie, M. Rose, and S. Waldbusser,
     "Structure of Management Information for Version 2
     of the Simple Network Management Protocol (SNMPv2)",
     RFC 1902, January, 1996.

[3]  Information processing systems -- Open Systems
     Interconnection -- Specification of Basic Encoding Rules
     for Abstract Notation One (ASN.1), International
     Organization for Standardization.  International Standard
     8825, (December, 1987).

[4]  M.Daniele, B. Wijnen, D. Francisco, "Agent Extensibility
     (AgentX) Protocol, Version 1," RFC 2257, January 1998.





















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