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Thomas Schmidt schmidt@informatik. haw-hamburg.de The RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring

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Page 1: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

The RTP MIB

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

Page 2: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

2

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

SSRC

Page 3: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

3

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

Page 4: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

4

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

Page 5: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

5

RTP MIB Tree

Root

ISO OrgDoD

InternetMgmt

MIB 1 & 287. RTP

MIB 1

MIB 2

Private

1. SessionNewIndex

1. Groups

7. RcvrTable

6. RcvrInverseTable

5. SenderTable

4. SenderInverseTable3. SessionTable2. SessionInverseTable

2. Compliances

1. MIBObjects

2. Conformance

Page 6: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

6

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}

RTP MIB

Page 7: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

7

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

Page 8: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

8

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 ….

Page 9: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

9

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)

Page 10: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

10

RTP Monitoring

Page 11: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

11

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

Page 12: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

12

RTT Probe Application for Cisco

Page 13: The RTP MIB - HAW Hamburgschmidt/nmm/RTP-MIB.pdfThe RTP MIB > Design of the RTP MIB > Application: Remote Multicast Monitoring . Thomas Schmidt schmidt@informatik. haw-hamburg.de 2

Thomas Schmidtschmidt@informatik.

haw-hamburg.de

13

Documents

RFC 2959 Real-Time Transport Protocol Management Information Base

J. Chesterfield, B. Fenner, L. Breslau: Remote Multicast Monitoring using RTP MIB, 2002.online: http://www.cl.cam.ac.uk/users/jac90/MMNS02.pdf