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Mbus Update. draft-ietf-mmusic-mbus-transport-02.txt. Jörg Ott [email protected] Colin Perkins [email protected] Dirk Kutscher [email protected] http://www.dmn.tzi.org/ietf/mmusic/mbus/. Quick Reminder. Local coordination mechanism Specification split into three pieces

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Mbus update

Mbus Update

draft-ietf-mmusic-mbus-transport-02.txt

Jörg Ott [email protected]

Colin Perkins [email protected]

Dirk Kutscher [email protected]

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Http www dmn tzi org ietf mmusic mbus
http://www.dmn.tzi.org/ietf/mmusic/mbus/

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Quick reminder
Quick Reminder

  • Local coordination mechanism

  • Specification split into three pieces

    • Requirements overview

    • Definition of the “transport protocol”

      • message syntax, addressing, local multicast, reliability, authentication, ...

    • Definition of the message semantics

      • call-control, media tools related commands

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Overview of changes in draft ietf mmusic mbus transport 02
Overview of Changes indraft-ietf-mmusic-mbus-transport-02

  • Bug-fixes

    • message syntax ABNF

    • minor corrections and clarifications

  • new section „Awareness of other Entities“

    • explicit specification of requirements for implementations

    • new algorithm for mbus.hello timer calculation deploying timer reconsideration

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Mbus entity awareness
Mbus Entity Awareness

  • General idea:

    • Each Mbus entity sends periodic heartbeat messages (mbus.hello)

    • Received hello-messages are used

      • to learn of the existence of other entities on startup (bootstrapping)

      • to track the aliveness of entities

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Mbus hello
mbus.hello

  • Fixed timer interval changed to dynamically adapted intervals

    • Scales according to number of entities

      • Number of mbus.hello received by an entity per time unit remains ~constant.

    • Deploys RTCP-like timer reconsideration mechanism to adapt to rapidly changing group size

      • Simpler than RTCP’s interval calculation because bandwidth fraction and sender vs. receiver is less important.

    • Uses randomization in order to avoid synchronization.

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Mbus ping
mbus.ping

  • Problem:

    • Increased timer intervals in larger groups can prolong bootstrapping phase.

  • Solution:

    • New command mbus.ping

    • query for the existence of other entities

    • learn their fully qualified Mbus addresses.

  • Example:

    • “Where’s the audio engine (if any)?”:

      • Send a mbus.ping to (media:audio).

      • Entities with matching addresses respond with mbus.hello.

      • Entity learns requested Mbus addresses

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Next steps
Next steps

  • Mbus-transport considered virtually stable

    • No further features/changes planned

    • Specification of behavior in the absence of Multicast could be useful.

      • Support for simple devices

  • One more draft submission before WG-last-call?

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Semantic specifications
Semantic specifications

  • Specify the usage of Mbus transport services in specific application areas

    • Definition of address classes, commands and semantics

  • Intended as Informational RFCs

  • Currently:

    • draft-ott-mmusic-mbus-semantics-00.txt

    • Commands for media engines and call-control

    • Has not been re-submitted yet

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Semantic specifications1
Semantic specifications

  • Plan:

    • Split-up specification into individual parts

    • Provide informational guidelines document for writing semantic specifications (work in progress)

  • Issue:

    • Which other command classes to go for?

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Other issues
Other Issues

  • Connecting physically separated Mbus domains

    • Independent of base spec.?

  • Simple devices

    • Mbus bootstrapping

      • How to obtain Mbus configuration parameters?

    • Allowing for Broadcast instead of Multicast?

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


Http www dmn tzi org ietf mmusic mbus1
http://www.dmn.tzi.org/ietf/mmusic/mbus/

48. IETF, Pittsburgh

Ott/Perkins/Kutscher


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