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Intelligent Packet Relay in Distributed Multimedia Systems

IP.com Disclosure Number: IPCOM000113094D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 120K

Publishing Venue

IBM

Related People

Herrtwich, RG: AUTHOR [+3]

Abstract

Described is the mixing of data streams in routers and mixers of digital networks. The routers must have a knowledge of the target addresses and available multicast features of the attached networks and the mixers have to know the algorithm to add data streams, the streams to add and some details on the data format.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 48% of the total text.

Intelligent Packet Relay in Distributed Multimedia Systems

      Described is the mixing of data streams in routers and mixers
of digital networks.  The routers must have a knowledge of the target
addresses and available multicast features of the attached networks
and the mixers have to know the algorithm to add data streams, the
streams to add and some details on the data format.

      Principles of Operation - Consider a multimedia application in
which data streams flow from m sources to n sinks.  On the way from
sources to sinks, the streams pass through a number of hops.  These
hops may be gateways, routers, bridges, switches, etc.  Call each
entity which relays multimedia data packets from an inbound to an
outbound channel an agent.  A typical agent copies incoming packets
to outbound channels without modification.  In contrast, an
intelligent agent can change packets on the way.

      Assume that changing packets is carried out by an add operation
which is the most frequent mixing operation.  Any add operation looks
like

      Snk_Chl=a[1]Src_Chl[1]+...+a[m]Src_Chl[m ]

      The syntax of add is determined by the knowledge of the
application.  In general, three kinds of such an add operation can be
identified:

      JOIN - A join defines an operation being performed by an
arithmetic add operation of all input channels.  Each input channel
can be defined to have a different relative magnitude or importance.
It is multiplied by a non-zero factor.  The result is sent to the
output.

      CHOICE - This implementation selects one input channel and
copies the respective data to the various output channels.

      Join and Choice - This most complicated approach allows for all
kind of mixing according to the audio mixer (hardware) paradigm.  In
term of mathematics it is a weighted sum of all input data allowing
also for factors with value zero.

      Components of the Intelligent Router - The tasks of an
intelligent relay can be decomposed into two functional units, router
and mixer.  In the following discussion the "mixer" is to be
considered equivalent to the "adder".  With these functional units
the intelligent router technique is described, but it is not
mandatory to implement this system by exactly the described
components.

      In Fig. 1 the routing table, the routing algorithm and the
routing service are summarized in one functional unit represented by
the box called router.

      If the routing does not support any multicast facility, than
the ratio between incoming and outgoing connections can be defined as
follows:

      |in[Routing]|=|out[Routing]|

      Routing including multicast facility:

      |in[Routing]|<=|out[Routing]|

      Adding standalone; whenever incoming streams of the same target
group meet in an agent they will be combined by the adder to produce
one intermediate stream:

      |in[Add]|>=|out[Add]|

      Intelligent Rel...