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Thomas Schmidt [email protected] The RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring

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  • Thomas [email protected]

    The RTP MIB

    > Design of the RTP MIB> Application: Remote Multicast Monitoring

  • Thomas [email protected]


    Management Information Base for Real-Time Transport

    > Defined in RFC 2959 for RTPv1 (RFC 1889)> Represents RTP/RTCP information for Hosts (end systems)

    and RTP Monitors – Translators & Mixers are excluded> Structured around the abstract concepts of

    – Session: association between participants, using the same destination RTP address (network address + RTP/RTCP ports)

    – Sender: source of an RTP session identified by SSRC– Receiver: unicast or multicast sink of RTP stream with unique


  • Thomas [email protected]


    Basic Use of RTP Management

    > RTP host systems may use RTP MIB to collect session & stream data from its sending & receiving

    > RTP monitors may use RTP MIB to collect session & stream statistical data (from RTCP) for surveying network performance and QoS values

    > RTP host monitors may survey endpoints receiving its streams – using session & sender data for its own sending, but receiver data from its peers

  • Thomas [email protected]


    Structure of RTP MIB

    > Essentially three tables– rtpSessionTable describes active sessions at the host or

    monitor– rtpSenderTable contains information about senders to RTP

    session– rtpRcvrTable contains information about RTP receivers

    > Three corresponding inverse tables– reverse lookup tables to easily identify rows in tables without

    search – used for group identification

  • Thomas [email protected]


    RTP MIB Tree


    ISO OrgDoD


    MIB 1 & 287. RTP

    MIB 1

    MIB 2


    1. SessionNewIndex

    1. Groups

    7. RcvrTable

    6. RcvrInverseTable

    5. SenderTable

    4. SenderInverseTable3. SessionTable2. SessionInverseTable

    2. Compliances

    1. MIBObjects

    2. Conformance

  • Thomas [email protected]


    RTP MIBmanagement applications. Rows created by management operations

    are deleted by management operations by settingrtpSessionRowStatus to 'destroy(6)'."

    INDEX { rtpSessionIndex }::= { rtpSessionTable 1 }

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


  • Thomas [email protected]


    Remote Multicast Monitoring

    Problem: Multicast traffic is intended for real-time distribution, but difficult to monitor:– Multicast distribution follows non-local transmission along a

    (shared) routing tree– Mcast membership as well as the distribution tree are

    dynamic and may change during its lifetime – Multicast (router) states are not present until traffic flows

    Background: RTP/RTCP and the MIB are designed to cope with multicast distribution

  • Thomas [email protected]


    Basic Credentials

    1. RTCP receiver reports are transmitted to session’s multicast address

    2. By creating an entry for a multicast group in the session table and setting it active and to monitor, the agent is caused to join that multicast group.

    3. Thereby the agent becomes a passive monitor.

    Problem: Active injection into the group ….

  • Thomas [email protected]


    Passive Monitoring

    RTP MIB is a QoS Watchdog> RTCP Data for Senders, Receivers and Sessions

    – Reports on activities, delay, jitter, loss …

    > Management for Hosts and Monitors– RTCP on Hosts and Monitors reports to group– Agent capable of sorting out data

    > Typical Point of Application: Gateway (e.g. AudioCodes Card)

  • Thomas [email protected]


    RTP Monitoring

  • Thomas [email protected]


    Active Monitoring

    RTT Mon observes QoS flaws before users> Proactively Implant QoS Probes

    – Exchange and evaluate RT probe packets– Supported by several vendors, e.g. Cisco Routers

    > Preconfigure Relevant Traversals– Have probes ready for critical paths of your network

    > Run on Suspicion or on Schedule– Preconfigure alarms/actions for automation

  • Thomas [email protected]


    RTT Probe Application for Cisco

  • Thomas [email protected]



    RFC 2959 Real-Time Transport Protocol Management Information Base

    J. Chesterfield, B. Fenner, L. Breslau: Remote Multicast Monitoring using RTP MIB,

    The RTP MIBManagement Information Base for Real-Time TransportBasic Use of RTP ManagementStructure of RTP MIBRTP MIB TreeRTP MIBRemote Multicast MonitoringBasic CredentialsPassive MonitoringRTP MonitoringActive MonitoringRTT Probe Application for CiscoDocuments